DE69832313T2 - Non-oriented electromagnetic steel sheet and method for its production - Google Patents

Description

Background of the invention

1. Field of the invention

The The present invention relates to a non-oriented electromagnetic sheet, that for electrical Materials for Electrical appliances used, is advantageous, and to a method of preparation thereof.

2. Description of the related State of the art

In The last few years have been from the point of view of saving energy of electrical appliances Electromagnetic sheets with low iron loss desired. There a coarsening of crystal grains is effective for lowering iron loss, is at non-oriented medium and high quality electromagnetic sheets, of which in particular it is required that they have low iron loss values containing 1 to 3% (Si + Al) tries to make the crystal grains coarser, by increasing the final tempering temperature up to 1000 ° C or by lowering the line speed for starting, which extends the start time becomes.

For a desirable Grain growth during the graduation ceremony It is effective, the content of impurities and precipitates in the steel sheet to reduce. To this end, many approaches have been undertaken to Impurities and precipitates harmless specifically to reduce the S content to prevent that MnS precipitates in high quality materials.

The tested Japanese Patent Publication No. 56-22931 discloses e.g. a trick for lowering the S content and the O content to 50 ppm or less or 25 ppm or less to reduce the iron loss in the steel, the Contains 2.5 to 3.5% Si and 0.3 to 1.0% Al.

The tested Japanese Patent Publication No. 2-50190 also discloses a fake for lowering the S content, O content and N content to 15 ppm or less, 20 ppm or less, or 25 ppm or less, to iron loss in the steel, which is 2.5 to 3.5% Si and 0.25 to 1.0% Al contains.

The unaudited Japanese Patent Publication No. 5-140647 also discloses a Artifice to reduce the S-content to 30 ppm or less and the Ti, Zr, Nb and V contents to 50 ppm or less to obtain the To reduce iron loss in the steel, the 2.0 to 4.0% Si and 0.10 contains up to 2.0% Al.

However, it is the present situation that the iron loss value of the high-quality steel sheet having an S content of 10 ppm or less is of the order of W _15/50 = 2.4 W / kg (with a sheet thickness of 0.5 mm) and that no iron loss values were achieved below this value. The loss of iron appears to be more easily reduced more and more as the MnS content is reduced, which is accompanied by a decrease in the S content, to facilitate crystal grain growth. However, the iron loss value described above is actually within its limit since a decrease in iron loss due to a reduced S content will be saturated at an S content of about 10 ppm.

DE 28 48 867 discloses non-oriented sheets characterized by a maximum sulfur content of 0.007 weight percent and a method of making the same.

Summary the invention

A Object of the present invention is to provide an electromagnetic sheet with low iron loss and a method for producing the same.

to solution The object of the present invention is a non-oriented one electromagnetic sheet prepared consisting of 0.005 wt .-% or less C, 0.2 wt% or less P, 0.005 wt% or less N, 4.5 wt% or less Si, 0.05 to 1.5 wt% Mn, 1.5 wt% or less than Al and 0.001 wt% or less S, at least one Item selected from the group consisting of 0.001 to 0.05 wt .-% Sb, 0.002 bis 0.1% by weight Sn, 0.0005 to 0.01% by weight Se and 0.0005 to 0.01% by weight Te and a balance of Fe and inevitable impurities.

In In the present invention, it is preferable that the S content is 0.0005 Wt .-% or less. The content of Ti as an inevitable impurity is more desirable Way 0.005 wt .-% or less.

The at least one element is preferably selected from the group consisting from 0.001 to 0.005 weight percent Sb, 0.002 to 0.01 weight percent Sn, 0.0005 to 0.002 wt% Se and 0.0005 to 0.002 wt% Te.

The preferred embodiments of the non-oriented electromagnetic sheet according to the present invention Invention are as follows:

Preferred embodiment 1:

Of the Si content is 4 wt% or less, Mn content is 0.05 to 1 wt .-%, the at least one element is Sb and Sn and the content at Sb + 0.5 × Sn is 0.001 to 0.05% by weight. It is preferred that the content of Sb + 0.5 × Sn 0.001 to 0.005 wt .-% is. The S content is preferably 0.0005 Weight or less.

Preferred embodiment 2:

Of the Si content is 4 wt% or less; the Mn content is 0.05 to 1% by weight, which is at least one element Sb; and the Sb content is 0.001 to 0.05% by weight. It is preferable that the Sb content is 0.001 to 0.005 wt .-% is. The S content is preferably 0.0005% by weight. Or less.

Preferred embodiment 3:

Of the Si content is 4 wt% or less, Mn content is 0.05 to 1 wt .-%, which is at least one element is Sn, and the Sn content 0.002 to 0.1% by weight. It is preferable that the Sn content is 0.002 to 0.01 wt .-% is. The S content is preferably 0.0005% by weight. Or less.

Preferred embodiment 4:

Of the Si content is 4 wt% or less, Mn content is 0.05 to 1 wt .-%, the Al content is 0.1 to 1 wt .-%, which is at least one Element is Se and Te, and the content of Se + Te is 0.0005 to 0.01% by weight. It is preferable that the content of Se + Te is 0.0005 to 0.002 wt .-% is. The S content is preferably 0.0005% by weight. Or less.

Preferred embodiment 5:

Of the Si content is 4 wt% or less, Mn content is 0.05 to 1 wt .-%, the Al content is 0.1 to 1 wt .-%, which is at least one Element is Se, and the Se content is 0.0005 to 0.01 wt%. It it is preferable that the Se content is 0.0005 to 0.002 wt%. Of the S content is preferably 0.0005 wt% or less.

Preferred embodiment 6:

Of the Si content is 4 wt% or less, Mn content is 0.05 to 1 wt .-%, the Al content is 0.1 to 1 wt .-%, which is at least one Element is Te, and the Te content is 0.0005 to 0.01 wt%. It it is preferable that the Te content is 0.0005 to 0.002 wt%. Of the S content is preferably 0.0005 wt% or less.

Preferred embodiment 7:

Of the Si content is 1.5 to 3 wt%, Al content is 0.1 to 1 wt%, the content of Si + Al is 3.5 wt% or less, at least one element is Sb and Sn, which is Sb + 0.5 × Sn content 0.001 to 0.05 wt%, and the sheet thickness is 0.1 to 0.35 mm. It it is preferable that the content of Sb + 0.5 × Sn is 0.001 to 0.005 wt%. is. It is desirable that the electromagnetic sheet has a mean crystal grain diameter from 70 to 200 μm having. The S content is preferably 0.0005 wt% or less.

Preferred embodiment 8th:

The Si content is 1.5 to 3 wt%, the Al content is 0.1 to 1 wt%, and the content of Si + Al is 3.5 Wt% or less, the at least one element is Sb, the Sb content is 0.001 to 0.05 wt%, and the sheet thickness is 0.1 to 0.35 mm. It is preferable that the Sb content is 0.001 to 0.005 wt%.

It is desirable that the electromagnetic sheet has a mean crystal grain diameter of 70 to 200 μm Has. The S content is preferably 0.0005 wt% or less.

Preferred embodiment 9:

Of the Si content is 1.5 to 3 wt%, Al content is 0.1 to 1 wt%, the content of Si + Al is 3.5 wt% or less, at least one element is Sn, the Sn content is 0.002 to 0.1 wt%, and the sheet thickness is 0.1 to 0.35 mm. It is preferable that the Sn content 0.002 to 0.01% by weight. It is preferred that the electromagnetic Sheet has a mean crystal grain diameter of 70 to 200 microns. The S content is preferably 0.0005 wt% or less.

Preferred embodiment 10:

Of the Si content is more than 3 wt .-% and 4.5 wt .-% or less, the Al content is 0.1 to 1.5 wt%, and the content of Si + Al is 4.5 Wt% or less, the at least one element is Sb and Sn, the content at Sb + 0.5 × Sn is 0.001 to 0.05 wt%, and the sheet thickness is 0.1 to 0.35 mm. The S content is preferably 0.0005 wt% or less.

Preferred embodiment 11:

sThe Si content is more than 3 wt .-% and 4.5 wt .-% or less, the Al content is 0.1 to 1.5 wt%, and the content of Si + Al is 4.5 Wt% or less, which is at least one element Sb, which is Sb content 0.001 to 0.05 wt%, and the sheet thickness is 0.1 to 0.35 mm. Of the S content is preferably 0.0005 wt% or less.

Preferred embodiment 12:

Of the Si content is more than 3 wt .-% and 4.5 wt .-% or less, the Al content is 0.1 to 1.5 wt%, and the content of Si + Al is 4.5 % By weight or less, the at least one element is Sn, which is Sn content 0.002 to 0.1% by weight, and the sheet thickness is 0.1 to 0.35 mm. Of the S content is preferably 0.0005 wt% or less.

Further, the present invention provides a non-oriented electromagnetic sheet consisting essentially of:
4% by weight or less of Si, 0.05 to 1% by weight of Mn, 0.1 to 1% by weight of Al, 0.001% by weight or less of S, and a balance of Fe and unavoidable impurities; and
300 ppm or less of nitride within a range of 30 μm from the surface of the sheet after a finish annealing.

• (a) Herstellen einer Platte bestehend aus 0,005 Gew.-% oder weniger C, 0,2 Gew.-% oder weniger P, 0,005 Gew.-% oder weniger N, 4 Gew.-% oder weniger Si, 0,05 bis 1 Gew.-% Mn, 1,5 Gew.-% oder weniger Al, 0,001 Gew.-% oder weniger S, zumindest einem Element ausgewählt aus der Gruppe bestehend aus 0,001 bis 0,05 Gew.-% Sb, 0,002 bis 0,1 Gew.-% Sn, 0,0005 bis 0,01 Gew.-% Se und 0,0005 bis 0,01 Gew.-% Te, und einem Rest an Fe und unvermeidlichen Verunreinigungen;
• (b) Heißwalzen der Platte unter Bildung eines heißgewalzten Blechs;
• (c) Kaltwalzen des heißgewalzten Blechs unter Bildung eines kaltgewalzten Blechs und
• (d) Abschluß-Anlassen ("finish-annealing") des kaltgewalzten Blechs.

The present invention also provides a method of making a non-oriented electromagnetic sheet comprising the steps of:

• (a) preparing a sheet consisting of 0.005 wt% or less C, 0.2 wt% or less P, 0.005 wt% or less N, 4 wt% or less Si, 0.05 to 1 wt% Mn, 1.5 wt% or less Al, 0.001 wt% or less S, at least one element selected from the group consisting of 0.001 to 0.05 wt% Sb, 0.002 to 0 , 1 wt% Sn, 0.0005 to 0.01 wt% Se and 0.0005 to 0.01 wt% Te, and a balance of Fe and unavoidable impurities;
• (b) hot rolling the plate to form a hot rolled sheet;
• (c) cold rolling the hot rolled sheet to form a cold rolled sheet and
• (d) finish-annealing the cold-rolled sheet.

In the method according to the present invention Invention, the at least one element from the group consisting from 0.001 to 0.05% by weight of Sb and 0.002 to 0.1% by weight of Sn.

Or The at least one element may be from the group consisting of 0.0005 to 0.01 wt.% Se and 0.0005 to 0.01 wt.% Te.

In the method for producing the non-oriented electromagnetic sheet according to the before preferred embodiments are as follows:

Preferred embodiment 1:

The Plate consists of 0.005 wt .-% or less C, 0.2 wt .-% or less P, 0.005 wt% or less N, 1 to 4 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 wt .-% or less Sb + 0.5 × Sn and a balance of Fe and inevitable impurities.

The Finishing tempering involves heating the cold-rolled sheet a heating rate of 40 ° C / s or fewer.

Preferred embodiment 2:

The Plate consists of 0.005 wt% or less C, 0.03 to 0.15 wt% P, 0.005 wt% or less N, 1 to 3.5 wt% Si, 0.05 to 1 Wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05% by weight of Sb + 0.5 × Sn and a balance of Fe and inevitable impurities.

The Finishing tempering involves continuous heating of the cold-rolled Steel in an atmosphere with a hydrogen concentration of 10% or more for a time from 30 s to 5 min.

Preferred embodiment 3:

The Plate is made of 0.005 wt% or less C, 0.2 or less P, 0.005 wt% or less N, less than 1.5 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 wt .-% or less Sb + 0.5 × Sn and a balance of Fe and inevitable impurities.

The Finishing tempering involves continuous heating of the cold-rolled Sheet metal in an atmosphere with a hydrogen concentration of 10% or more for a time from 30 s to 5 min.

Preferred embodiment 4:

The Method according to the present invention The invention further comprises the step of heating or tempering of the hot rolled Sheet.

The Plate consists of 0.005 wt .-% or less C, 0.2 wt .-% or less P, 0.005 wt% or less N, 1.5 to 4 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 wt .-% or less Sb + 0.5 × Sn and a balance of Fe and inevitable impurities.

The Tempering the hot rolled Sheet includes heating the hot rolled Sheet in a mixed atmosphere of hydrogen and nitrogen at a heating rate of 40 ° C / s Or less.

Preferred embodiment 5:

The Method according to the present invention Invention also includes the step of tempering the hot rolled sheet.

The Plate consists of 0.005 wt .-% or less C, 0.15 wt .-% or less P, 0.005 wt% or less N, 1.5 to 3.5 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 wt .-% or less Sb + 0.5 × Sn and a balance of Fe and inevitable impurities.

The Tempering the hot rolled Sheet includes heating the hot rolled Sheet metal in an atmosphere with a hydrogen concentration of 60% or more over 1 to 6 hours.

Preferred embodiment 6:

The Method according to the present invention Invention also includes the step of tempering the hot rolled sheet.

The Tempering the hot rolled Sheet includes heating the hot rolled Sheet metal in an atmosphere with a hydrogen concentration of 10% or more for 1 to 5 minutes.

Short description the drawings

1 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

2 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

3 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

4 Fig. 12 is a graph indicating the relationship between the Sn content and the iron loss after finish annealing.

5 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after magnetic tempering.

6 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after magnetic tempering.

7 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after magnetic tempering.

8th Fig. 12 is a graph indicating the relationship between the Sn content and the iron loss after magnetic tempering.

9 Fig. 12 is a graph indicating the relationship between the Ti content and the iron loss after the finish annealing.

10 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

11 FIG. 12 is a graph indicating the relationship between the Se content and the iron loss after termination tempering. FIG.

12 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after finish annealing in a steel sheet having a thickness of 0.5 mm.

13 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after finish annealing in a sheet having a thickness of 0.35 mm.

14 Fig. 12 is a graph indicating the relationship between the S content and the Sb content and the iron loss after finish annealing.

15 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

16 Fig. 12 is a graph indicating the relationship between the Sn content and the iron loss after finish annealing.

17 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after finish annealing in a sheet having a thickness of 0.5 mm.

18 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after finish annealing in a sheet having a thickness of 0.35 mm.

19 is a graph showing the relationship between the S and Sb contents and the iron loss after indicates completion of the start.

20 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

21 Fig. 12 is a graph indicating the relationship between the Sn content and the iron loss after finish annealing.

22 Fig. 12 is a graph indicating the relationship between the average crystal grain diameter and the iron loss after finish tempering.

23 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

24 Fig. 12 is a graph indicating the relationship between the S and Sb contents and the iron loss after finish tempering.

25 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

26 Fig. 12 is a graph indicating the relationship between the Sn content and the iron loss after finish annealing.

27 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

28 Fig. 10 is a graph indicating the nitride content within a range of 30 μm from the steel surface and magnetic characteristics after finish tempering.

29 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

30 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

31 FIG. 12 is a graph indicating the relationship between the heating rate at final tempering and the iron loss after finish tempering.

32 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

33 FIG. 12 is a graph indicating the relationship between soaking time for finish tempering and iron loss after finish tempering. FIG.

34 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

35 FIG. 12 is a graph indicating the relationship between the annealing time for finish annealing and the iron loss after finish annealing. FIG.

36 Fig. 12 is a graph indicating the relationship between the S content and the iron loss after termination tempering.

37 Fig. 12 is a graph indicating the relationship between the heating rate when heating the hot-rolled sheet and the iron loss after finish tempering.

38 Fig. 12 is a graph indicating the relationship between the Sb content and the iron loss after finish tempering.

39 is a graph showing the relationship between the S content and the iron loss after Ab indicates termination.

40 FIG. 12 is a graph indicating the relationship between soaking time for annealing a hot rolled sheet and iron loss after finish tempering. FIG.

description of the preferred embodiments

Embodiment 1:

Of the crucial point of this embodiment is that the formation of nitrides can be suppressed by (Sb + Sn / 2) is contained in an amount of 0.001 to 0.05 wt .-%, whereby the iron loss is lowered, on the basis of new discovery that iron loss can be reduced, even when the S content is reduced to a trace amount of 10 ppm or less is, because significant nitride layers on the surface area, a trace amount contains at S be formed.

consequently can solve the above problem by a non-oriented solved electromagnetic sheet are made up, in wt .-%, 0.005% or less C, 0.2% or less P, 0.005% (including Zero) or less N, 4% or less Si, 0.05 to 1.0% Mn and 1.5% or less Al in addition to 0.001% (including Zero) S and 0.001 to 0.05% (Sb + Sn / 2) with a substantial balance Fe and inevitable impurities.

If the content of (Sb + Sn / 2) is set in the range of 0.001 to 0.005% is, the iron loss can be significantly reduced.

In In the following description, "%" and "ppm" refer to the composition of the steel, to "% by weight" or "ppm by weight".

(Process of the invention and the reason for the limitation of the contents of S, Sb and Sn)

To investigate the effect of S on iron loss, the inventors of the present invention have made a steel having a composition of 0.0025% C, 2.85% Si, 0.20% Mn, 0.010% P, 0.31% Al and O, 0021% N was melted in the laboratory with a change in the S content from a trace amount to 15 ppm, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours, followed by cold rolling to a sheet thickness of 0.5 mm. The cold-rolled sheet was subjected to finish annealing in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. The relationship between the S content and the iron _loss value W _{15/50 of} the sample thus obtained is in 1 shown (the symbol x in 1 ). Magnetic measurements were made using the 25 cm Epstein method.

1 shows that a high degree of decrease in iron loss is achieved when the S content is set to 10 ppm or less, indicating that a critical point is around an S content of 10 ppm. The reason for this is that grains are well developed by reducing the S content. Therefore, the S content in the present invention is limited to 10 ppm or less.

If however, if the S content is lowered below 10 ppm, the rate of decrease becomes the iron loss so slow that, even if a trace amount of Sn, the iron loss is not 2.4 W / kg or less can be made.

The Inventors of the present invention have assumed that the reason for this, that the decrease in iron loss in the material with extremely low S content decreases, could be based on unknown reasons and have considered its texture under an optical microscope. The Results showed that significant nitride layers on the surface layer of the steel sheet in the range of Sn content of 10 ppm or were observed less. In contrast, little nitride layers were in the range with an S content found by more than 10 ppm.

The reason for accelerating the nitriding reaction when decreasing in the S content may be as follows: Since S is easily concentrated at the surface layer and the grain boundaries, it suppresses absorption of nitrogen on the surface layer of the sheet from the atmosphere in the S content range of more than 10 ppm, which prevents the formation of nitride layers. On the other hand, in the S content range of 10 ppm or less, the preventive effect for nitrogen absorption by S is so deteriorated that Nitride layers are formed on the surface layer of the sheet.

The Researchers hypothesized that the nitride layer formed on the surface could prevent crystal grain growth, causing a decrease of iron loss suppressed would.

On Based on this concept, the researchers had the idea that the Formation of the nitride layer could be suppressed while that Crystal grain growth favors is going to decrease with iron loss by some others Elements as S that suppress the absorption of nitrogen are included. As a result of collective studies of these elements, it has been noted that Sb is effective.

Samples prepared by allowing the above-mentioned sample designated by the symbol x to contain 40 ppm of Sb were tested under the same conditions. The results are in 1 indicated with the symbol o. The effect of Sb for reducing iron loss is described. Although iron loss could not be reduced to a value of the order of 0.02 to 0.4 W / kg by allowing Sb to be contained in the sample containing more than 10 ppm of S, the value was reduced by about 0, 2 W / kg is reduced in the S content range of 10 ppm or less, which clearly shows the iron loss reducing effect when the S content is small. In addition, no nitride layers were observed in this sample regardless of the S content. This result suggests that Sb was concentrated on the surface of the sheet suppressing nitrogen absorption, as a result, iron loss was decreased because grain growth was not disturbed.

For the purpose of examining the optimum Sb content, a steel having a different composition of 0.0026% C, 2.70% Si, 0.20% Mn, 0.020% P, 0.30% Al, 0.0004% S and 0.0020% N with varying content of Sb from trace amount to 70 ppm in the laboratory, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then tempered in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. Then, the hot-rolled sheet was cold-rolled to a sheet thickness of 0.5 mm, followed by finish tempering in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. The relationship between the Sb content and W _15/50 is in 2 shown.

2 shows that the iron loss is reduced in the Sb content range of 10 ppm or less, thereby achieving a W _15/50 iron loss _value of 2.25 to 2.35 W / kg, which has never been achieved in conventional electromagnetic sheets. However, if Sb is added further up to a Sb content of more than 50 ppm, the iron loss is increased again. However, the increase of W _15/50 remains in the range of 2.25 to 2.35 W / kg up to a Sb content of 700 ppm, a level never reached in conventional electromagnetic sheets.

Around the reason for the iron loss increase in the Sb content range of more than 50 To examine ppm, the texture of the material under an optical Looking at a microscope. The result showed that, although none Texture of fine surface grains observed was to be slightly larger the mean crystal grain diameter appeared. Since Sb tends to segregate at grain boundaries, is believed, although it is not certain that grain growth is suppressed by a grain boundary resistance effect of Sb.

Out the above reasons the Sb content is limited to the range of 10 ppm or more under economical Considerations of 500 ppm or less. However, it is beneficial to limit the Sb content below 50 ppm, the range of 20 to 40 ppm is more preferable for the reason described above.

Under the assumption that the same effect by adding different elements could be achieved led the researchers carried out an experiment that focused on the effect of Sn concentrated.

To study the effect of S on iron loss as in the previous experiments, a steel having the composition 0.0020% C, 2.85% Si, 0.18% Mn, 0.01% P, 0.30% was used. Al, 0.0018% N and 0.0020% Ti varying in the content of S from a trace amount to 15 ppm were melted in the laboratory, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then tempered in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. Then, the steel sheet was cold rolled to a sheet thickness of 0.5 mm, followed by finish annealing in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. The relationship between the S content and W _15/50 is in 3 shown (the symbol x in 3 ). The magnetic measurement was carried out using the 25 cm Ep performed stone method.

Out 3 For example, it can be confirmed that a high degree of iron loss reduction is achieved at an S content of 10 ppm or less, indicating that a critical point in the S content is about 10 ppm. The decrease in iron loss becomes slow when the S content is 10 ppm or less, and the iron loss value can not be lowered below 2.4 W / kg even if a trace amount of S is contained.

Samples prepared by allowing the previous sample, marked with an x symbol, to contain 60 ppm Sb were tested under the same conditions. The results are in 3 represented by the symbol o. The effect of Sn for reducing iron loss will be explained. While the iron loss decreases by only 0.02 to 0.04 W / kg when Sn is added to the sample having an S content range of not more than 10 ppm, the iron loss was about 0.2 W / kg in the S content range of 10 ppm or less, indicating that the effect of Sn for reducing iron loss becomes obvious when the S content is low. Regardless of the S content, no nitride layers were observed in this sample. This means that Sn is concentrated on the surface of the sheet by suppressing nitrogen absorption; consequently, the crystal grain growth was not disturbed, whereby the iron loss decreased.

To study the optimum Sn content, a steel having the composition 0.0025% C, 2.72% Si, 0.20% Mn, 0.020% P, 0.30% Al, 0.0002% S, 0 , 0020% N and 0.0010% Ti having a varying content of Sn from a trace amount to 1400 ppm were melted in the laboratory, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then tempered in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. Then, the steel sheet was cold rolled to a thickness of 0.5 mm, followed by finish annealing in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. The relationship between the Sn content and W _15/50 is in 4 shown.

4 proves that the iron loss is reduced in the Sn content range of 20 ppm or more, whereby W _15/50 = 2.25 to 2.35 W / kg is attained; this is a level never achieved with conventional electromagnetic steels. While the iron loss increases again when the Sn content is more than 100 ppm, the value of W _15/50 = 2.25 to 2.35 W / kg, which has never been achieved in conventional electromagnetic steels, in Sn Content range can be achieved up to at least 1400 ppm.

Around the reason for the iron loss increase in the Sn content region of more than 100 To examine ppm, the texture of the material under an optical Looking at a microscope. The results showed that, although none Surface grain texture was observed, the mean crystal grain diameter slightly smaller was. Since Sn tends to segregate at grain boundaries Although this is not certain that the grain growth is suppressed by a grain boundary resistance effect of Sn. Also in this sample, no nitride layers were observed, and Regardless of the S content, which is the suppression of nitrogen absorption by attributed the concentrated Sn to the surface layer of the sheet can be.

Out the above reasons For example, the Sn content in the present invention is in the range of 20 ppm or more and from the economical point of view 1000 ppm or less. However, it is advantageous to have the Sn content from the one described above Limit reason below 100 ppm, the range of 40 to 80 ppm being more preferred.

The the above results can on the electromagnetic steel sheet of high quality, which is a high Contains concentration of Si, i.e. 1% or more Si. In the expectation that the iron loss by the same method as described above low-quality electromagnetic sheet containing 1% or less of Si is reduced could be, we performed the following experiment.

A steel having the composition 0.0026% C, 0.21% Si, 0.55% Mn, 0.10% P, 0.27% Al and 0.001% N with a change in the S content from a trace amount to 15 ppm, was melted in the laboratory, followed by washing with an acid solution after hot rolling. Subsequently, this hot rolled sheet was cold rolled and subjected to finish tempering in an atmosphere of 10% H ₂ -90% N ₂ at 750 ° C for 1 minute, followed by magnetic tempering in 100% N ₂ at 750 ° C for 2 hours ,

5 Fig. ₁₄ shows the relationship between the S content and the iron _loss W _{15/50 of} the sample obtained (the symbol x in the figure). The magnetic measurement was carried out using a 25 cm Epstein test piece.

5 shows that the iron _loss W _15/50 becomes 4.3 W / kg or less when the S content is 10 ppm or less, indicating that the iron loss is greatly reduced. On the other hand, when the S content is 10 ppm or less, the rate of decrease of iron loss becomes slow and finally reaches only a iron loss value of 4.2 W / kg even if the S content has further decreased. The same tendency is observed when the S content is more than 1%.

A sample containing 40 ppm of Sb in addition to the sample components previously marked by the symbol x was tested under the same conditions as described above. The results are in 5 shown by the symbol o.

Of the Effect of Sb to reduce iron loss becomes below explained. While the iron loss is only reduced by 0.02 to 0.04 W / kg by Sb is added to the sample with an S-content region greater than 10 ppm Iron loss is reduced by 0.20 W / kg by adding Sb in the sample is given with an S-content of 10 ppm or less, which clearly indicates an iron loss lowering effect of Sb, though the S-content is small. In this sample, regardless of the S content no nitride layer observed, resulting as the result of the concentrated Sb on the surface of the sheet under suppression the absorption of nitrogen is considered.

For the purpose of studying the effect of optimum Sb content, a steel having a composition of 0.0026% C, 0.20% Si, 0.50% Mn, 0.120% P, 0.25% Al, 0.0004% S was used and 0.0020% N with a change in the Sb content from one trace to 700 ppm in the laboratory, followed by acid washing after hot rolling. Subsequently, this hot rolled sheet was cold rolled to a sheet thickness of 0.5 mm and subjected to finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 750 ° C for 1 minute, followed by magnetic tempering in 100% N ₂ followed at 750 ° C for 2 hours.

6 shows the relationship between the Sb content and the iron _loss W _15/50 . Out 6 It can be seen that the iron loss in the Sb region decreases by 10 ppm or more, thereby achieving a W _15/50 iron _{loss value} of 4.0 W / kg or less. However, if Sb is further added up to a Sb content of more than 50 ppm, the iron loss slowly decreases as the Sb content increases.

Of the Iron loss remains better than that of steel without Sb, itself when the Sb content is increased up to 700 ppm.

Under consideration Of the results described above, the Sb content should be 10 ppm or more, with its upper limit from the economic point of view 500 ppm. In view of iron loss, the content is more desirable Way 10 ppm or more and 50 ppm or less in a desirable Range of 20 to 40 ppm.

The Researchers expected the same effect by adding Sn as well in the case of adding Sb in the low-quality magnetic sheet with a To obtain Si content of 1% or less. Therefore, the following became Experiment performed.

To investigate the effect of S-content on iron loss, a steel having the composition 0.0020% C, 0.25% Si, 0.55% Mn, 0.11% P, 0.25% Al and 0 was used , 0018% N with a change in the S content from one to 15 ppm in the laboratory, followed by washing with an acid solution after hot rolling. Subsequently, this hot rolled sheet was cold rolled to a sheet thickness of 0.5 mm and subjected to finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 750 ° C for 1 minute, followed by magnetic tempering in 100% N ₂ at 750 ° C for 2 hours.

7 shows the relation between the S content in the obtained sample and the iron _{loss value} W _15/50 (the symbol x in the figure). The magnetic measurement was carried out using a 25 cm Epstein test piece.

Out 7 It can be seen that while the iron _loss W _{15/50 is} greatly reduced to 4.3 W / kg as in the previous sample in the S content range of 10 ppm or less, the decrease in iron loss becomes slow when the S content 10 ppm or less, with only up to 4.2 W / kg, even if the S content is further lowered.

A sample containing 80 ppm Sn in addition to the sample components previously identified by a symbol x was tested under the same conditions as described above. The result tate are in 7 shown by the symbol o. The effect of Sn for reducing iron loss will now be described. While the iron loss is lowered only by 0.02 to 0.04 W / kg by adding Sn in the sample having an S content of more than 10 ppm, the iron loss is lowered by 0.20 to 0.30 W / kg by adding Sn to the sample having an S content of 10 ppm or less, thereby clearly showing the iron loss reducing effect of Sb when the S content is small. No nitride layer was observed in this sample regardless of the S content, which is considered to be the result of concentrated Sn on the surface layer of the sheet while suppressing absorption of nitrogen.

For the purpose of examining the optimum Sn content, a steel having the composition 0.0021% C, 0.25% Si, 0.52% Mn, 0.100% P, 0.26% Al, 0.0003% S and 0 was used 0.015% N with a change in Sn content from a trace amount to 1300 ppm in the laboratory, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was cold rolled to a sheet thickness of 0.5 mm and subjected to finish tempering in an atmosphere of 10% H ₂ -90% N ₂ at 750 ° C for 1 minute, followed by magnetic tempering in 100% N ₂ at 750 ° C for 3 hours.

8th shows the relation between the Sn content in the sample thus obtained and W _15/50 .

8th suggests that the iron loss in the Sn content range decreases from 20 ppm or more to reach an iron _{loss value} W _15/50 of 4.0 W / kg or less. If Sn is further added to a Sn content of more than 100 ppm, however, the iron loss slowly increases again.

Of the Iron loss remains better than that of a steel without Sn, itself if Sn is up to 1300 ppm.

Out the reasons above the upper limit of the Sn content is determined to be 1000 ppm, and below From an economic point of view, the upper limit is limited to 500 ppm. However, it is advantageous to limit the Sn content below 100 ppm, wherein the range of 40 to 80 ppm is more preferable to a lower To get iron loss value.

The Difference of effects on iron loss at Sn and Sb can be like to be understood.

There Sn has a smaller sedimentation coefficient than Sb required an Sn content of about 2 times the content of Sn is. Consequently, the iron loss by adding 20 ppm or reduced more at Sn. On the other hand, the additional amount of Sn, the iron loss due to the resistance effect as a result of Grain boundary sedimentation of Sn, which is about 2 times the amount at Sb, since Sn has a smaller sedimentation coefficient than Sb has.

As previously described, the mechanism by which the Nitride formation suppressed becomes identical between Sb and Sn.

consequently has a simultaneous addition of Sb and Sn a suppressive effect for the Nitride formation on. However, for Sn is twice the amount of Amount of Sb needed, to show the same effect as Sb.

In In the present invention, Sb and Sn are in the same group classified and the amount of (Sb + Sn / 2) is on the range of 0.001 to 0.05% limited. The more preferred range for (Sb + Sn / 2) is limited to the range of 0.001 to 0.005%.

(The reason why the other other components are limited)

Of the Reason why the other components are limited, is below described.

C: The content of C is because of the problem of magnetic aging limited to 0.005% or less.

P: Although P is an element that helps to improve the lancing properties sheet is required, its content is 0.2% or less limited, since an addition of more than 0.2% makes the sheet brittle.

N: Because a big one Amount of N precipitate an amount of AlN leaves, which increases iron loss, its content is limited to 0.005% or less.

Si: Although Si is an essential element for increasing the self-resistance of the Sheet metal tends to magnetic flux density with decrease the saturation of the magnetic flux density when its content exceeds 4.0%. Therefore, the upper limit for his salary 4.0%.

Mn: More than 0.05% Mn is necessary to get red brittleness during hot rolling to prevent. However, since the magnetic flux density at a Mn content is reduced by 1.0% or more, its range is up 0.05 to 1.0% limited.

al: Although Al as Si is an essential element for increasing the self-resistance, causes a lot of over 1.5% a decrease in magnetic flux density along with the decrease in saturation the magnetic flux density. Therefore, the upper limit is 1.5%. The Lower limit is 0.1%, because if the Al content is less than 0.1%, the grain size of AlN becomes so fine that grain growth is degraded.

(Production method)

to Production of the non-oriented electromagnetic sheet can be done in conventional in the present invention Procedures are applied, provided that the claimed Composition is adhered to. The melted in a converter melted Steel is degassed to make it to a prescribed composition after which it is subjected to casting and hot rolling. The final treatment temperature and the "coiling" temperature at hot rolling are not necessarily prescribed, but for the production a conventional one Electromagnetic sheet can be applied to a normal temperature range become. A tempering after hot rolling is, although it is not is forbidden, not essential. After forming the steel into one Sheet metal of a prescribed thickness through a cold rolling process or by two or more cold rolling operations with an intermediate annealing, the interposed, the steel sheet may be a final tempering be subjected.

example

(Example 1)

By using a steel having an Si content of 1% or less, as shown in Table, the steel was subjected to casting after adjusting it to a given composition by applying a post-purge degassing treatment in the converter. The steel was hot rolled after heating the plates for 1 hour at a temperature of 1160 ° C to a sheet thickness of 2.0 mm. The finishing temperature and the coiling temperature during hot rolling were 800 ° C and 670 ° C, respectively. Then, this hot-rolled sheet was washed with an acid solution, and after cold-rolling to a sheet thickness of 0.5 mm, the sheet was tempered in an atmosphere of 10% H ₂ -90% N ₂ under finish annealing conditions shown in Table 1 are subject. Finally, magnetic annealing was applied to the panel in an atmosphere of 100% N ₂ at 750 ° C for 2 hours.

The magnetic measurement was carried out using a 25 cm Epstein test piece ((L + C) / 2). The magnetic characteristics (iron _loss W _15/50 and magnetic flux density B ₅₀ ) are shown together in Table 1.

No. 1 to No. 17 in Table 1 are examples of the invention in which the Si content is of the order of 0.25%. Nos. 22 to 27 are the examples of the present invention in which the Si content is on the order of 0.75%. The iron _loss W _15/50 in each example is much lower than the value of 4.2 W / kg, which is a level considered difficult to achieve in conventional sheet metals. The values are 3.94 to 4.05 W / kg and 3.36 to 3.45 W / kg in the samples containing Si in the order of 0.25% and 0.75%, respectively.

The magnetic flux density B ₅₀ shows a high level of 1.76 T and 1.73 T in the steels having an Si content of the order of 0.25% and 0.75%, respectively.

On the other hand, the contents of S and (Sb + Sn / 2) in the sample of No. 18 are out of the range of the present invention. The S content in No. 19 and No. 20 and the (Sb + Sn / 2) content in No. 21 are also outside the scope of the present invention. Consequently, the iron _loss W _{15/50 is} high in all cases.

Both the content of S and (Sb + Sn / 2) in the sample No. 28, which has a Si level of 75%, are outside the scope of the present invention. The S content in Sample No. 29 and the (Sb + Sn / 2) content in Sample No. 30 are also outside the scope of the invention. Consequently, its iron _loss W _{15/50 is} higher than that of the inventive samples having the same level of Si content.

As From these examples and comparative examples, a non-oriented electromagnetic steel sheet with a very low iron loss after magnetic tempering or magnetic annealing are obtained without decreasing the magnetic flux density, when the composition of the steel sheet to the S and (Sb + Sn / 2) content levels according to the first preferred embodiment of Invention is controlled.

(Example 2)

A steel was refined in a converter, followed by degassing, and then pouring after adjustment to prescribed compositions prepared in 2 and 3 are shown subjected. The plate was heated at 1200 ° C for 1 hour and hot-rolled to a sheet thickness of 2.0 mm, thereby obtaining a steel sheet containing 1% Si. The finishing temperature of the hot rolling was 800 ° C. The coiling temperatures of the hot rolling were 650 ° C and 550 ° C for the steel sheets Nos. 31 to 40 and Nos. 41 to 72, respectively. The plates Nos. 41 to Nos. 72 were hot rolled under the conditions shown in Table 2 and Table 3. The atmosphere for annealing the hot rolled sheet was 75 H ₂ -25% N ₂ . The hot-rolled sheet was washed with an acid solution and then cold-rolled to a sheet thickness of 0.5 mm, finally subjected to final tempering under the conditions shown in Tables 2 and 3 in an atmosphere of 25% H ₂ -75% N ₂ .

The magnetic measurement was carried out using a 25 cm Epstein test piece ((L + C) / 2). The magnetic properties (iron _loss W _15/50 and magnetic flux density B ₅₀ ) of each steel sheet are also shown in Table 2 and Table 3.

Of the sheets shown in Table 2, the Si contents of No. 31 to No. 40 were at a level of 1.05%, while the Si contents of No. 41 to No. 48 were at a level of 1.85 , The iron loss values of the sheets No. 31 to No. 37 and No. 41 to No. 46 according to the present invention having the above-described Si levels were lower than the iron loss values of the steel sheet not belonging to the present invention. The S and (Sb + Sn / 2) contents of the plates No. 38 and No. 47, the S content of the steel plate No. 39, and the (Sb + Sn / 2) content of the plates No. 40 and No. 48 were outside the scope of the present invention, exhibiting a higher iron _loss W _15/50 than the sheets having the same Si levels.

Table 3 shows the experimental results of the steels with Si levels of 2.5 to 3.0%, whose contents are identical to those in Table 2. Nos. 49 to 63 correspond to the steels according to the present invention which show lower iron loss values than the other steels. The S and (Sb + Sn / 2) contents of No. 64, the S content of No. 65 and the (Sb + Sn) contents of No. 66 and No. 67 were outside the scope of the present invention , higher iron _{loss values} showed W _15/50 than the steels of the present invention having the same Si level.

Since Steel No. 68 contains a higher level of C than the level of the present invention, not only does it have a high iron _loss W _15/50 , but it also involves the problem of magnetic aging.

Since the Mn content of the steel No. 69 is out of the range of the present invention, it not only has a high iron _loss W _15/50 , but also a lower magnetic flux density B ₅₀ .

The iron _loss W _{15/50 of} the steel No. 70 is lowered while the magnetic flux density B _{50 is} low because the Al content is out of the range of the present invention.

Since the N content of No. 71 is out of the range of the present invention, the iron _loss W becomes _15/50 .

Although the iron _loss W _15/50 is pushed to a lower level, its magnetic flux density B ₅₀ becomes small because the Si content falls outside the range of the present invention.

If the Si content over 1% and within the Si levels according to the present invention The iron loss value of the steel sheet remains low without that the magnetic flux density is reduced, provided that that the levels of other components within the range of present invention.

For the purpose of studying the stable productivity of the steel according to the present invention, a steel having a composition of 0.0025% C, 2.85% Si, 0.20% Mn, 0.01% P, 0.31% Al, O was used , 0021% N, 0.0003% S and 40 ppm Sb are melted, followed by washing with an acid solution after hot rolling. The hot-rolled sheet was then annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. Then, the hot-rolled sheet was cold-rolled to a sheet thickness of 0.5 mm, followed by finish tempering in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. The result indicates that the iron loss values spread widely between 2.2 to 2.6 W / kg were.

Around the reasons for the To examine the above result, a thin film was removed from the sample after Graduation launching made to look at it through a TEM. While no fine precipitates in the sample with low iron loss were observed TiN grains with a grain size of about 50 nm observed in the sample with high iron loss. This result shows that the cause of the dispersion in iron loss is in the precipitation of fine TiN grains could.

To study the effect of Ti on grain growth, a steel having the composition 0.0015% C, 2.87% Si, 0.20% Mn, 0.01% P, 0.31% Al, 0.0021 % N, 0.0003% S and 40 ppm Sb were melted in the laboratory with a varying amount of Ti, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then subjected to annealing in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C. for 3 hours. After cold rolling to a sheet thickness of 0.5 mm, the sheet was subjected to finish annealing in an atmosphere of 25% H ₂ -75% N ₂ at 900 ° C for 1 minute. 9 shows the relationship between the Ti content in the sample and the iron _loss W _15/50 after finish annealing.

It can be out 9 It is recognized that the iron _loss W _15/50 becomes 2.35 W / kg or less when the Ti content is 50 ppm or less, indicating that steels having a stable iron loss can be obtained.

consequently For example, the Ti content becomes 50 ppm or less, more preferably 20 ppm or less, limited.

Table 4

Embodiment 2:

Of the critical point of this embodiment of the present invention is that in material containing a trace amount at S of 10 ppm or less, the iron loss of the non-oriented electromagnetic sheet to be greatly reduced can be done by either Se or Te or both in one area of Total concentration of 0.0005 to 0.01% are included.

The The above problem may be due to a non-oriented electromagnetic Tin can be solved with a low iron loss, characterized by it is that it is in wt% 0.005% or less C, 4.0% or less Si, 0.05 to 1.0% Mn, 0.2% or less P, 0.005% or less (including zero) N, 0.1 to 1.0% Al, 0.001% or less (including zero) S and 0.0005 to 0.01% of at least one element selected from the group consisting from Se and Te, and a balance of Fe and unavoidable impurities contains.

One Low iron loss value can be obtained by adding the content on the at least one element selected from the group consisting from Se and Te, is limited to 0.0005 to 0.002%.

Process of the invention

The Researchers of the present invention investigated the exact reasons for the inhibition the iron loss decrease in the material that is a trace amount S of 10 ppm or less. From the result it became clear that recognizable nitride layers the surface layer of the steel were formed, indicating that this nitride layer a reduction in iron loss disturbs.

consequently the researchers have the method for further reduction of iron loss by suppressing of nitride formation, where they found that the iron loss of the material containing a trace amount of S on a large scale by adding at least one element selected from the group consisting from Se and Te, selected can be lowered in an amount of 0.0005 to 0.01%.

(The reason why the Levels of S, Se and Te are limited)

The The present invention will be described with reference to the experimental Results described in more detail.

To investigate the effect of S on iron loss, a steel having the composition 0.0025% C, 2.85% Si, 0.20% Mn, 0.01% P and 0.31% Al with a varying amount of S was used from a trace to 15 ppm melted in the laboratory, then washed after hot rolling with an acid solution. This hot-rolled sheet was then annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was then cold rolled to a sheet thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 1 minute.

10 Fig. ₁₄ shows the relationship between the S content of the sample thus obtained and the iron _loss W _15/50 (the symbol x in the figure). Out 10 It can be seen that a large decrease in iron loss, ie W _15/50 = 2.5 W / kg, was achieved when the S content was adjusted to 10 ppm or less. The reason is that the grains could develop well by reducing the S content.

Out From the above reason, the S content becomes in the present invention to 10 ppm or less, more desirable Way to 5 ppm or less, limited.

If however, the S content was decreased to 10 ppm or less, The rate of iron loss will be so slow that your Value finally only 2.4 W / kg is reached, even if the S content is further lowered.

The Researchers believe that the reason why the decline of the Iron loss in the material containing a trace amount of S of 10 contains ppm or less, is inhibited, may have other unknown causes than MnS and observed the tissue under observation under an optical microscope clear nitride layers on the steel surface layer in the S-content range of 10 ppm or less. In contrast, the nitride layers in the Sample with S-content of more than 10 ppm rarely found. It will assumed that this nitride layer at the time of annealing or Gets started and led a graduation start of the hot rolled Sheet in a nitrogen atmosphere through.

The reason why the nitride forming reaction is accelerated with decrease of the S content may be as follows.
Since S is an element that can be easily concentrated at the surface and grain boundaries, the S concentration at the surface of the sheet is high in the S content range of more than 10 ppm, whereby the absorption of nitrogen at the time of annealing and the annealing Final tempering of the hot rolled sheet is suppressed. On the other hand, the suppressive effect of nitrogen absorption by S is reduced to the S content range of 10 ppm or less.

Researchers believe that the precursor nitride layer in the material containing a trace amount of S could hinder crystal grain growth on the surface layer of the sheet, thereby suppressing a decrease in iron loss. Based on this concept, the researchers had the idea that the iron loss in the material containing a trace amount of S is further reduced For example, if elements capable of suppressing nitrogen absorption and unable to inhibit grain growth in the material containing a trace amount of S could be allowed to exist in the material. As a result of intensive studies, we found that a trace amount of Se is effective.

The sample in which 10 ppm of Se was added in addition to the components of the previous sample indicated by the symbol x was tested under the same conditions as described above. The results are in 10 shown. The following explains the effect of Se for reducing iron loss. While iron loss is only reduced by 0.02 to 0.04 W / kg by adding Se in the sample containing more than 10 ppm S, the iron loss is reduced by about 0.20 W / kg by the addition of Se in the sample containing 10 ppm or less S decreases. Thus, the effect of Se for lowering the iron loss becomes clear when the S content is small.

In regardless of the S content, these samples did not become nitride layers observed. The reason is that Se at the surface layer of the sheet below suppression concentrated nitrogen absorption.

To study the optimum amount of Se addition, a steel having the composition 0.0026% C, 2.70% Si, 0.20% Mn, 0.020% P, 0.30% Al, 0.0004% S was used and 0.0020% N with a varying concentration of Se ranging from trace amount to 130 ppm in the laboratory, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then annealed in an atmosphere of 75% H ₂ -15% N ₂ at 830 ° C for 3 hours. Then, the sheet was cold rolled to a sheet thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 1 minute.

11 shows the relationship between the Se content and the iron _loss W _15/50 . Out 11 It is understood that the iron loss in the region of Se addition of 5 ppm or more decreases to reach a W _15/50 value of 2.25 W / kg, which is a value which is equivalent to that of the conventional electromagnetic steel sheet (Si + Al) content of 3 to 3.5% has never been achieved. It also becomes clear that iron loss begins to reappear when Se is further added to a level of greater than 20 ppm.

To the Purpose of investigating the reason why the iron loss in the Range of Se> 20 ppm increased is, the sample was viewed under an optical microscope. The result showed that, although no fine-grained texture in the surface layer was found, the average crystal grain size was slightly smaller. The reason is, if he is not sure that the grain growth in a row a grain boundary resistance effect of Se was deteriorated because Se settles easily at the grain boundaries.

If Se is added up to 130 ppm, the iron loss value is lower than the value of the steel that contains no Se. Consequently, the Se content becomes set to 5 ppm or more, and its upper limit is lowered economic point of view defined as 100 ppm. The desirable one Content is 5 ppm or more and 20 ppm or less to the iron loss value keep low.

the same Effect to reduce iron loss was also observed when Te was added. Therefore, the addition amount of Te is as in Se, limited to 5 ppm or more, with the upper limit below economic The point of view is 100 ppm. The desirable content is 5 ppm or more and 20 ppm or less to low the iron loss value to keep.

Similar Effects of simultaneous addition of Se and Te were also confirmed. consequently For example, the combined addition amount of Se and Te became 5 ppm or more limited, the upper limit from an economic point of view 100 ppm. The desirable one Content is 5 ppm or more and 20 ppm or less to iron loss keep low.

(The reason why the Contents of other components are limited)

Of the Reason will be described below.

C: The C content became 0.005% due to magnetic aging less limited.

Si: Although Si is an effective element for enhancing the self-resistance is, the magnetic flux density decreases with saturation the magnetic flux density decreases when the content exceeds 4.0%. Therefore, the upper limit was set at 4.0%.

Mn: Although 0.05% or more Mn to prevent the red brittleness during hot rolling is required, the magnetic flux density is reduced when the content is 1.0% or more. Consequently, the Mn content is on the Range limited from 0.05 to 1.0%.

P: P is an essential element for improving the pinning properties. However, because the sheet is fragile will if Mn over 0.2% is added, the content is limited to 0.2% or less.

N: If N in a big one Amount is included, a lot of AlN under increasing the Iron loss precipitated. Therefore, the content is limited to 0.005% or less.

al: While Al to increase of self-resistance is essential, causes a content of more than 1.0% that the magnetic flux density with the reduction the saturation the magnetic flux density decreases. Therefore, the upper limit set at 1.0%. The lower limit was set at 0.1%, because fine AlN grains be formed under deterioration of crystal grain growth, if the content is less than 0.1%.

(Production method)

conventional Process for the preparation of non-oriented electromagnetic Sheet metal can in the present invention, provided that the contents of S, Se and Te are in a given range. Of the molten steel, which has been refined in a converter, is degassed, to be adjusted to a prescribed composition, whereupon he is pouring and hot rolling is subjected. The temperature of the final tempering and the coiling temperature at the hot rolling is not necessarily prescribed, but it can be in one normal temperature range for producing a conventional electromagnetic sheet lie. A tempering after the hot rolling Although not prohibited, it is not essential. After shaping of the steel to a sheet of a prescribed thickness a cold rolling or by twice or more cold rolling with an interposed annealing or tempering, it will Steel sheet subjected to a completion tempering.

example

A steel listed in Table 5 was used, the steel was subjected to casting after being adjusted to a given composition by using a refining treatment after refining in the converter. The steel was hot-rolled after heating the plate at a temperature of 1200 ° C for 1 hour to a sheet thickness of 2.0 mm. The finish temperature of the hot rolled steel was 800 ° C, while the coiling temperature for the plate No. 1 to No. 6 was 800 ° C and for the other plates was 550 ° C. Annealing treatments of the hot-rolled sheet under the conditions listed in Table 6 were applied to the steel sheets Nos. 7 to 35. The sheets were cold rolled to a sheet thickness of 0.5 mm, then subjected to tempering under the conditions for finish tempering listed in Table 6. The sheets with the same numbers in Tables 5 and 6 correspond to the same sheet. The atmosphere of annealing the hot rolled sheet and the atmosphere of final tempering warn 75% H ₂ -25% N ₂ and 10% H ₂ -90% N _2, respectively.

The Magnetic properties were measured using 25 cm Epstein test pieces. The magnetic properties of each steel sheet are also in table 6 indicated.

The Si levels of Sample Nos. 1 to 6, Nos. 7 to 11 and Nos. 12 to 35 are 1.0 to 1.1%, 1.8 to 1.9% and 2.7 to 3, respectively , 0% (with a small number of exceptions). When the samples are compared with the same level of Si content, it becomes clear that the sheet according to the invention has a smaller iron _loss W _15/50 than the comparative _steels .

The above results show that a sheet with a very low Iron loss after section tempering can be obtained if the contents of S, Se and Se in the composition of the sheet according to the present invention Be controlled invention.

The S and (Se + Te) contents in Sheet No. 4, the S content in Sheet No. 5, and the (Se + Te) content in No. 6 steel are all outside the scope of the present invention. Therefore, their iron _{loss values} W _{15/50 are} high.

Similarly, the S and (Se + Te) contents are in sheet No. 10, the (Se + Te) content in the sheet No. 11 outside the scope of the present invention, indicating high iron _{loss values} W _15/50 .

In addition, the S and (Se + Te) contents in sheet No. 27, the S content in sheet No. 28, and the (Se + Te) content in sheet No. 29 and 30 are all outside the range of present invention. Therefore, their iron _{loss values} W _{15/50 are} high.

The Sheet # 31 has a problem with magnetic aging because of C content exceeds the range of the present invention.

The sheet No. 32 has a low iron _loss W _15/50 , but the magnetic flux density is small because the Si content exceeds the range of the present invention.

The magnetic flux density B _{50 of} the sheet No. 33 is small because the Mn content exceeds the range of the present invention.

The sheet No. 34 has a low iron _loss W _15/50 , but the magnetic flux density is small because the Al content exceeds the range of the present invention.

Sheet No. 35 has a large iron _loss W _15/50 because the N content exceeds the range of the present invention.

Table 5

Embodiment 3

Of the critical point of this embodiment The present invention is an electromagnetic sheet with a high magnetic flux density and a low iron loss in a wide frequency range, the engines of electric cars is required to obtain by the thickness of a sheet in which the S content is set to 0.001% or less, and a given Amount added to Sb or Sn, adjusted to 0.1 to 0.35 mm becomes.

The problem described above can be solved by an electromagnetic sheet having a thickness of 0.1 to 0.35 mm, which in wt .-% 0.005% or less C, 1.5 to 3.0% Si, 0.05 to 1.5% by weight of Mn, 0.2% or less P, 0.005% or less (including zero) N and 0.1 to 1.0% Al, 3.5% or less (Si + Al), 0.001% or less S (including zero) and 0.001 to 0.05% (Sb + Sn / 2) with a balance of Fe and unavoidable impurities.

In addition, lower Iron loss values can also be obtained by the (Sb + Sn / 2) content on the range is limited from 0.001 to 0.005%.

In The following description refers to "%" Representation of the composition of the steel on "wt .-%" and "ppm" relates to "ppm by weight".

Process of the invention

To investigate the effect of S-content on iron loss, researchers of the present invention first melted a steel having the composition 0.0026% C, 2.80% Si, 0.21% Mn, 0.01% P, 0 , 32% Al and 0.0015% N with a varying amount of S from a trace level to 15 ppm in the laboratory in vacuo, followed by annealing of the hot rolled sheet in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours after hot rolling and washing with an acid solution.

Subsequently, this hot rolled and annealed sheet was cold rolled to a sheet thickness of 0.5 and 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes , The magnetic properties were measured by a 25 cm Epstein method.

Since high torque is required in an electric car at a low frequency region of about 50 Hz, the sheet is magnetized at about 1.5T. At a high frequency region of about 400 Hz, such a high torque is not required, so that the sheet can be magnetized at about 1.0T. Therefore, the iron loss W _15/50 was when the sheet was magnetized to 1.5 T, it is judged at a frequency of 50 Hz while the iron loss W _15/50 when magnetized to 1.0 T, for the evaluation at a frequency of 400 Hz was used. 12 _Fig . ₁₄ shows the relationship between the S content of a material having a thickness of 0.5 mm and the iron _loss W _15/50 .

12 shows that the iron loss W _{15/50 is} greatly reduced at 50 Hz in the material having a thickness of 0.5 mm when the S content is less than 10 ppm.

The iron _loss W _15/50 at 400 Hz, however, is greatly increased when the S content is lowered. To investigate the reason for these iron loss changes associated with the decrease of the S-content, the texture of the material was observed under an optical microscope. The result shows that the crystal grains were coarser when the S content was 0.001% or less. The reason is likely that the content of MnS in the steel was decreased.

From this texture change, the dependence of iron loss at frequencies of 50 Hz and 400 Hz on the S content can be understood as follows:
In general, iron loss is classified into two categories hysteresis loss and eddy current loss. It is known that the hysteresis loss is reduced while the eddy current loss is increased as the crystal grain diameter increases. Since hysteresis loss at a frequency of 50 Hz is a dominant factor, a decrease in S content and associated coarsening of crystal grains will cause a decrease in hysteresis loss, thereby reducing iron loss. However, since the eddy current loss at a frequency of 400 Hz is predominant, the eddy current loss is increased by lowering the S content and thereby coarsening crystal grains to increase the iron loss.

Out From the above discussions it can be concluded that, although a reduction of the S content in the material with a thickness 0.5 mm to reduce iron loss in low frequency regions is effective, it has an inverse effect of reducing the Iron loss in high frequency regions.

13 shows the relation between the S content in the material having a thickness of 0.35 mm and the iron loss. The figure shows that the iron _loss W _{15/50 of} the material having a thickness of 0.35 mm at a frequency of 50 Hz as in the material having a thickness of 0.5 mm is greatly reduced when the S content is 10 ppm or less.

However, unlike the result in the material having a thickness of 0.5 mm, the iron loss W _15/50 at 400 Hz is also decreased when the S content is lowered. The reason for this is because the eddy current loss in the material having a thickness of 0.35 mm is greatly reduced as compared with that of the material having a thickness of 0.5 mm due to the reduced plate thickness, a reduction in hysteresis loss as a result of coarsening the crystal grain size causes a reduction of the total iron loss.

In The above discussions make it clear that a reduction of the S-content in the sheet of 0.35 mm thickness makes it possible that the iron loss in the regions of high to low frequency is reduced. Consequently, the S content and the sheet thickness become limited to 10 ppm or less or 0.35 mm or less.

A Reduction of iron loss in high to low frequency regions when the S-content decreased, it became more apparent when the sheet thickness in the electromagnetic sheet with a thickness of 0.35 mm or less thinner has been. However, if the sheet thickness is less than 0.1 mm the application of cold rolling difficult, combined with a load for customers through a lot of work to laminate the sheets. Consequently, the film thickness becomes limited to 0.1 mm or more in the present invention.

The Processes such as iron loss in the material with a thickness of 0.35 mm was further investigated.

to It is usually effective to reduce iron loss Increase Si and Al content, to increase the intrinsic resistance. However, engines of electric cars have increases in Si content and Al content not desirable, because then a decrease in torque is caused. Therefore were some other procedures than increase the Si and Al contents examined.

As in 13 is shown, the decrease rate of iron loss is slowed down when the S content is 10 ppm or less, finally reaching an iron _loss level of 2.3 W / kg at W _15/50 and 18.5 W / kg at W _10/400 becomes.

Under the assumption that a reduction of iron loss in one Material containing a trace amount of S of 10 ppm or less Certain unknown factors other than MnS could be inhibited the researchers of the present invention, the texture of the material under an optical microscope. The result showed that at the surface layer of the steel in the S-content region of 10 ppm or less Nitride layers were found, whereas little nitride layers in the S-content region of more than 10 ppm. It will assumed that this nitride layer during annealing and Final annealing of the hot rolled Sheet is formed.

Of the Reason why the nitride formation reaction with decrease of the S-content accelerated, may be the following: Since S is an element, that's easy on the surface and concentrated at the grain boundaries suppresses concentrated S on the surface of the sheet an absorption of nitrogen during tempering in the S-content region of more than 10 ppm. In the salary region of However, the suppression effect for nitrogen absorption can be 10 ppm or less be reduced due to the presence of S.

The Researchers hypothesized that the nitride layer contained in the material, containing a trace amount of S, noticeably, can inhibit a decrease in iron loss. Based on this concept, the researchers had the idea that an addition of elements that capable is to suppress the absorption of nitrogen and not the grains disturbs, to develop well, it is possible could make that the iron loss of the material containing a trace amount of S continues is reduced. After collective studies, we found that the addition of Sb and Sn is effective.

The test results obtained by adding 40 ppm of Sb to the sample in 14 and 13 are described below. The effect of reducing the iron loss of Sb will be explained. While the iron _{loss values} W _15/50 and W _{10/400 are} only 0.02 to 0.04 W / kg and 0.2 to 0.3 W / kg, respectively, by adding Sb in the S-content region of more than 10 ppm The values were decreased by 0.20 to 0.30 W / kg and 1.5 W / kg at W _15/50 and W _{10/400, respectively,} by the addition of Sb in the S-content region of 10 ppm or less which shows a clear reduction effect of Sb on iron loss when the S content is low. No nitride layers were observed in this sample, regardless of the S content, presumably due to concentrated Sb on the surface layer of the sheet suppressing nitrogen absorption.

The The above results clearly show that a high degree of reduction in iron loss possible in a wide frequency range is made without any reduction in the magnetic flux density is effected by placing Sb in the material having a sheet thickness of 0.35 mm containing a trace amount of S is given.

To study the optimum amount of addition of Sb, a steel having the composition 0.0026% C, 2.75% Si, 0.30% Mn, 0.02% P, 0.35% Al, 0.0004 % S and 0.0020% N with a varying amount of Sb from a trace amount to 700 ppm in the laboratory melted in vacuum, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes. 15 _Fig . ₁₄ shows the relationship between the Sb content of the sample thus obtained and the iron _loss W _15/50 and W _10/400 .

Out 15 It can be seen that the iron loss in the region of the Sb addition decreases by 10 ppm or more, with the W _15/50 and W _10/400 values of 2.0 W / kg and 17 W / kg, respectively , However, if the Sb content was increased to more than 50 ppm by adding more Sb, the iron loss slowly decreases with the increase of the Sb content.

To the Purposes of investigation of the reason for increase of iron loss in of the Sb content region of more than 50 ppm, the texture became less examined by an optical microscope. The result showed that, although on the surface no nitride layers were found, the crystal grain diameter something was small. Although the exact reasons are not clear, that could Grain growth hampered by a grain boundary resistance effect of Sb because Sb is an element that is easily deposited at the grain boundaries can be.

Even if Sb is added up to 700 ppm, compared to the Steel without Sb obtained a lower iron loss value. After these As a result, the Sb content was defined as 10 ppm and its upper limit was economically limited to 500 ppm. Considering the iron loss values should be 10 ppm or more and 50 ppm or less, more preferably 20 ppm or more and 40 ppm or less be.

Since Sn as well as Sb is an element that is easily deposited at grain boundaries, the same effect for suppressing nitride formation can be expected. In order to study the optimum amount of added Sn, a steel having the composition 0.0020% C, 2.85% Si, 0.31% Mn, 0.02% P, 0.30% Al, 0 was prepared in the laboratory under vacuum , 0003% S and 0.0015% N were melted with a varying amount of Sb from a trace amount to 1400 ppm, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes.

16 _Fig . ₁₀ shows the relationship between the Sn content of the sample thus obtained and the iron _loss W _15/50 and W _10/400 .

Out 16 It is understood that the iron loss in the region of Sn addition decreases by 20 ppm, whereby W _15/50 and W _10/400 of 2.0 W / kg and 17 W / kg, respectively, are achieved. In addition, when the Sn content increases to 100 ppm or more, the iron loss gradually increases as the Sn content increases. However, iron loss remains low compared to a steel without Sn, even if Sn is added up to 1400 ppm.

The Difference of effect on iron loss by Sn and Sb can be understood as follows.

There Sn has a smaller segregation coefficient than Sb becomes about twice the amount of Sn compared to Sb to suppress the Nitride formation by surface segregation needed by Sn. Therefore, the iron loss by the addition of Sn at 20 ppm or more reduced. The required additional amount by which the iron loss due to a resistance effect due to Sn segregation at the grain boundaries is also twice the amount of sb, since Sn is a smaller one Has segregation coefficient as Sb. Accordingly, a Adding 100 ppm or more of Sn, the iron loss slowly increases.

Out From the above facts, the Sn content is determined to be 20 ppm or more and its upper limit is raised from an economic point of view 1000 ppm limited. In terms of iron loss is the desirable Content 20 ppm or more and 100 ppm or less, more preferably 30 ppm or more and 90 ppm or less.

As discussed above are the mechanisms of Sb and Sn for suppression the nitride formation identical. Therefore, make a simultaneous addition from Sb and Sn it possible a similar one suppression effect for the To obtain nitride formation. However, Sn should be in double Amount of the amount of Sb to be added to allow Sn shows the same degree of effect as Sb. Consequently, the amount should be to (Sb + Sn / 2) 0.001% or more and 0.05% or less, more desirably 0.001% or more and 0.005% or less when Sb and Sn are simultaneously be added.

(The reason why the Contents of other components are limited)

Of the Reason why the contents of other components are limited should be described below.

Of the C content became 0.005% or less because of magnetic aging limited.

There Si is an effective element to increase Of the inherent resistance of the sheet metal, it will be in a crowd of 1.5% or more added. On the other hand, the upper limit of the Si content became limited to 3.0%, since the magnetic flux density decreases with the decrease the saturation the magnetic flux density decreases when its content exceeds 3.0%.

It more than 0.05% Mn is necessary to get red brittleness during hot rolling to prevent. However, since the magnetic flux density in the Mn content was reduced by 1.5% or more, was his range limited to 0.05 to 1.5%.

Although P is an element that is used to improve the Stan properties of the Sheet is required, its content was 0.2% or less limited, since an addition of more than 0.2% makes the sheet brittle.

There a big Amount of N precipitate an amount of AlN leaves, if the AlN grains coarser can, can the grains do not develop well and iron loss increases. Therefore was its content is limited to 0.005% or less.

Fine AlN grains, which are formed by adding a trace amount of Al show the tendency for the magnetic properties to deteriorate are. Therefore, its lower limit should be 0.1% or less the AlN grains to make rude. On the other hand, the upper limit is set to 1.0% or less fixed, because the magnetic flux density at an Al content is reduced by 1.0 or more. However, if the amount of (Si + Al) exceeds 3.5%, the magnetic flux density is combined with the gain of the Magnetizing current decreases so that the value of (S + Al) is limited to 3.5% or less.

(Production method)

It can conventional Method for producing the electromagnetic sheet in the present invention, provided the contents S, Sb and Sn are in a given range. The melted Steel, which has been refined in a converter, is degassed, to adjust the prescribed composition, after that he's a pour and a hot rolling subjected. The temperature of the final tempering and the coiling temperature at the hot rolling are not necessarily prescribed, but may be in a usual Area for making a conventional electromagnetic Sheet lie. An annealing or tempering after hot rolling Although not prohibited, it is not essential. After forms of the steel to a sheet of a prescribed thickness a cold rolling process or by twice or more cold rolling with an intervening annealing, the sheet undergoes a final tempering subjected.

A steel as shown in Table 7 was subjected to casting after adjustment to a given composition by employing a degassing treatment after refining in the converter. The steel was hot rolled to a sheet thickness of 2.0 mm after the sheet had been heated to a temperature of 1150 ° C for 1 hour. The finishing temperature and coiling temperature were 750 ° C and 610 ° C. Then, this hot-rolled sheet was washed with an acid solution, then subjected to hot rolling and annealing under the conditions given in Table 7. The atmosphere of hot rolling and tempering was 75% H ₂ -25% N ₂ . Then, the sheet was cold-rolled to a thickness of 0.1 to 0.5 mm and finally subjected to tempering under the conditions of finish annealing indicated in Table 8 and Table 9. The final tempering atmosphere was 10% H ₂ -90% N ₂ .

The Magnetic measurement was carried out using a 25 cm Epstein test piece ((L + C) / 2). The magnetic characteristics of each sheet are shown in Table 7 to Table 9. The attached sheet metal numbers are in both Tables equal.

The sheets Nos. 7 to 13, Nos. 15 to 21 and Nos. 24 to 27 in Table 7 to Table 9 are the sheets according to the present invention. It becomes clear that the iron _{loss values} W _15/50 , W _10/400 and W _{5 / 1k} are lower in all these sheets and that the magnetic flux density B ₅₀ in all these sheets is higher when compared with the other sheets.

in the Sheet metal No. 1, however, the iron loss is very high, since the content at S and (Sb + Sn) and the sheet thickness outside the range of the present Invention lie. The iron loss in plate no. 2 is also very high, because the value for (Sb + Sn) and the sheet thickness outside within the scope of the present invention.

Since the sheet thickness in the sheet No. 3 is out of the range of the present invention, the iron _loss W _{15/50 is} low, while W _10/400 and W _{5/1 k are} high.

The contents of S and (Sb + Sn) in the sheets No. 4 and No. 22, the S content in the sheet No. 5 and the (Sb + Sn) content in the sheets No. 6, No. 14 and No. 23 are outside the scope of the invention. Therefore, the iron _loss W _{15/50 is} high.

The contents of (Si + Al) and (Sb + Sn) in the sheet No. 28 are outside the scope of the invention, so that the magnetic flux density B _{50 is} low.

Since the contents of Si and (Si + Al) in the sheet No. 29 and the (Si + Al) content in the sheet No. 30 are each outside the range of the present invention, the iron loss is low, but also the magnetic flux density B ₅₀ low.

Of the Al content in sheet metal No. 31 is outside the lower limit of present invention, whereby the iron loss is high and the magnetic flux density is low.

The Al content is above the upper limit, and the (Si + Al) content is out of the range of the invention, so that the magnetic flux density B _{50 is} low.

In the sheet No. 33, the iron loss is large since its Al content is below the lower limit of the present invention, while the magnetic flux density B _{50 is} low because the Mn content in the sheet No. 34 is above the upper limit of the present invention.

Of the C content in sheet No. 35 is out of the scope of the invention, so the iron loss is high, next to a problem the magnetic aging.

There the N content of sheet No. 36 is out of the range of the present Invention is the iron loss is high.

Table 7

Embodiment 4

Of the essential point of this embodiment The present invention is an electromagnetic sheet with a high magnetic flux density and low iron loss in a wide frequency range, required in electric car engines is to obtain by the thickness of a sheet in which the S content is set to 0.001% or less and a given amount is added to Sb or Sn is adjusted to 0.1 to 0.35 mm.

The The problem described above may be due to an electromagnetic plate with a thickness of 0.1 to 0.35 mm and a mean crystal grain diameter in the sheet of 70 to 200 microns solved are, in wt .-%, 0.005% or less C, 1.5 to 3.0% Si, 0.05 to 1.5% by weight of Mn, 0.2% or less of P, 0.005% or less (including Zero) N, 0.1 to 1.0% Al, 3.5% or less (Si + Al), 0.001% or less S (including Zero) and 0.001 to 0.05% (Sb + Sn / 2) with a balance of Fe and unavoidable Contains impurities.

In addition, lower Iron loss values can also be obtained by the content of (Sb + Sn / 2) is limited to the range of 0.001 to 0.005%.

In The following description refers to "%" and "ppm" in the illustration the composition of the steel to "wt .-%" or "ppm by weight", unless stated otherwise.

Process of the invention

To study the effect of S-content on iron loss, researchers of the present invention first have a steel having the composition 0.0026% C, 2.80% Si, 0.21% Mn, 0.01% P, 0 , 32% Al and 0.0015% N with varying amount of S from a trace amount to 15 ppm in the laboratory, vacuum-fused, followed by annealing the hot-rolled sheet in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours after hot rolling and washing with an acid solution.

Subsequently, this hot rolled and annealed sheet was cold rolled to a sheet thickness of 0.5 and 0.35 mm, followed by finish tempering in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes. The magnetic properties were measured by a 25 cm Epstein method.

Since high torque is usually required in the low frequency region of about 50 Hz in an electric car, the sheet is magnetized to about 1.5T. On the other hand, in a high frequency range of about 400 Hz, no such high torque is required, so that the sheet can be magnetized at about 1.0T. Therefore, the iron loss W _15/50 was when the sheet was magnetized to 1.5 T, it is judged at a frequency of 50 Hz while the iron loss W _15/50 when magnetized to 1.0T was, for the evaluation at a frequency of 400 Hz was used. 17 _Fig . ₁₅ shows the relationship between the S content of a material having a thickness of 0.5 mm and the iron _loss W _15/50 and W _10/400 .

17 indicates that the iron loss W _{15/50 is} greatly reduced at 50 Hz in the material having a thickness of 0.5 mm when the S content is less than 10 ppm.

In contrast, the iron loss W _15/50 at 400 Hz is greatly increased when the S content is reduced. To investigate the cause of these iron loss changes associated with the decrease in S-content, the texture of the material was observed under an optical microscope. The result showed that crystal grains were coarse to about 100 μm when the S content was 0.001% or below. The reason is probably that the content of MnS in the steel has been reduced.

From this texture change, the S content dependence on iron loss at frequencies of 40 Hz and 400 Hz can be understood as follows:
In general, iron loss is classified into two categories, hysteresis loss and eddy current loss. It is known that the hysteresis loss decreases as the eddy current loss increases as the crystal grain diameter is increased. Since hysteresis loss is a major factor in iron loss at a frequency of 50 Hz, a decrease in S content and concomitant coarsening of crystal grains will cause a decrease in hysteresis loss, thereby reducing iron loss. Since the eddy current loss is a major factor for the iron loss at a frequency of 400 Hz, the eddy current loss due to the decrease of the S content and the accompanying coarsening of crystal grains is increased to increase the iron loss.

Out From the above discussions it can be concluded that, although a decrease in the S content in the material with a thickness of 0.5 mm to reduce iron loss in low frequency regions effectively is, they have a reverse effect to reducing iron loss in high frequency regions.

18 Fig. 15 shows the relationship between the S content in the material having a thickness of 0.35 mm and the iron loss. 18 shows that the iron _loss W _{15/50 of} the material having a thickness of 0.35 mm at a frequency of 50 Hz, as in the material having a thickness of 0.5 mm, is greatly reduced when the S-Ge just 10 ppm or less.

However, unlike the result with the material having a thickness of 0.5 mm, the iron loss W _15/50 at 400 Hz is also reduced when the S content is decreased. The reason is that since the eddy current loss in the material having a thickness of 0.35 mm is greatly reduced as compared with that of the material having a thickness of 0.5 mm due to the reduced plate thickness, a reduction in hysteresis loss as a result of coarsening of crystal grains causes a decrease in total iron loss.

Out From the above discussions it becomes clear that a reduction in the S content in the sheet with a thickness of 0.35 mm a reduction in iron loss in high to low frequency regions. Hence the S content and the sheet thickness to 10 ppm or less or 0.35 mm or less limited.

A Reduction of iron loss in the high to low frequency ranges with a decrease in S content was more evident when the sheet thickness the electromagnetic sheet with a thickness of 0.35 mm or less thinner has been. However, if the sheet thickness is less than 0.1 mm the application of cold rolling difficult associated with the load from customers through a lot of work to lamination of steel sheets. consequently For example, the film thickness in the present invention is 0.1 mm or more limited.

The Processes such as iron loss in the material with a thickness of 0.35 mm was further investigated.

to It is usually effective to reduce the iron loss by and increase Al content to to increase the intrinsic resistance. However, increases in Si content and Al content in engines of electric cars not desirable, because a torque reduction is caused. Therefore, other procedures as an increase investigated the Si and Al contents.

As in 18 is shown, the rate of decrease of iron loss is slowed down when the S content is 10 ppm or less, finally having an iron _{loss level} of 2.3 W / kg at W _15/50 and 18.5 W / kg at W _10/400 reached.

Under the assumption that a reduction of iron loss in one Material containing a trace amount of S of 10 ppm or less Some other unknown factors could be inhibited as MnS the researchers of the present invention, the texture of the material under an optical microscope. The result showed that in the surface layer of the steel of the S-content region of 10 ppm or less recognizable Nitride layers were found, whereas little nitride layers were found in the S-content region of more than 10 ppm. It will assumed that this nitride layer during the tempering and final annealing of the hot rolled Sheet metal was formed.

Of the Reason why the nitride formation reaction with the decrease of the S-content can be as follows: Since S is an element that light on the surface and concentrated at grain boundaries, concentrated S at the surface of the sheet, the absorption of nitrogen during annealing or Tempering in the S-content region of more than 10 ppm. In the salary region of 10 ppm or less, on the other hand, the suppression effect for one Nitrogen absorption by the presence of S be reduced.

The Researchers believed that the above nitride layer, the in the material containing a trace amount of S is remarkably formed will prevent the iron loss from decreasing. On the base this concept, the researchers had the idea that an addition of Elements that are capable suppress the absorption of nitrogen, and the good development of grains do not bother, the iron loss of the material containing a trace amount of S, on could reduce. After extensive studies, we found that the addition of Sb and Sn is effective.

The sample by adding 40 ppm Sb to the sample, which in 18 was prepared under the same conditions and the results are in 19 shown. The effect of reducing the iron loss of Sb is determined as follows. While the iron _{loss values} W _15/50 and W _{10/400 decrease} only by 0.02 to 0.04 W / kg and 0.2 to 0.3 W / kg, respectively, when Sb in the S-content region exceeds 10 ppm was added, the values decreased by 0.20 to 0.30 W / kg and 1.5 W / kg for W _15/50 and W _{10/400, respectively,} by the addition of Sb in the S-content region of 10 ppm or less, which shows an obvious iron loss reduction effect of Sb when the S content is low. Regardless of the S content, no nitride layers were observed in this sample, presumably due to the concentrated Sb at the surface layer of the sheet under suppression of nitrogen absorption.

The The above results clearly show that a large extent of the reduction in iron loss is made possible in a wide frequency range without that a decrease in the magnetic flux density is caused by Sb in the material with a sheet thickness of 0.35 mm, which is a trace amount contains at S is given.

To study the optimum amount of Sb additive, a steel having the composition 0.0026% C, 2.75% Si, 0.30% Mn, 0.02% P, 0.35% Al, 0.0004 % S and 0.0020% N with a varying amount of Sb from one trace to 700 ppm in the laboratory under vacuum, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes. 20 _Fig . ₁₄ shows the relation between the Sb content of the sample thus obtained and the iron _loss W _15/50 and W _10/400 .

Out 20 It can be seen that the iron loss in the region of the Sb addition decreases by 10 ppm or more, whereby values of W _15/50 and W _10/400 of 2.0 W / kg and 17 W / kg, respectively, are achieved. However, when the Sb content was increased to more than 50 ppm by adding further Sb, the iron loss slowly decreases with the increase of the Sb content.

To the Purposes of investigation of the cause of iron loss increase in The Sb content region of more than 50 ppm underwent the texture an optical microscope. The result showed that, although on the surface no nitride layers were found, the crystal grain diameter something was small. Although the exact reasons are not clear, that could Grain growth hampered by a grain boundary resistance effect of Sb because Sb is an element that is easily deposited at grain boundaries can be.

Even when Sb is added at up to 700 ppm, compared to to obtain a lower iron loss value for the steel without Sb.

To From these results, the Sb content was defined to be 10 ppm and its Upper limit was from economic point of view to 500 ppm limited. Considering the iron loss values should be 10 ppm or more and 50 ppm or less, more desirable 20 ppm or more and 40 ppm or less.

Since Sn as well as Sb is also an element that is easily deposited at grain boundaries, the same effect for suppressing nitride formation can be expected. In order to investigate the optimum addition amount of Sn, a steel having a composition of 0.0020% C, 2.85% Si, 0.31% Mn, 0.02% P, 0.30% Al, 0.0003 was used in the laboratory % S and 0.0015% N with a varying amount of Sb from one trace to 1400 ppm in vacuum, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes.

21 _Fig . ₁₀ shows the relationship between the Sn content of the sample thus obtained and the iron _loss W _15/50 and W _10/400 .

Out 21 It is understood that the iron loss in the region of Sn addition decreases from 20 ppm to reach W _15/50 and W _10/400 of 2.0 W / kg and 17 W / kg, respectively. If the Sn content is further increased to 100 ppm or more, it can be seen that the iron loss increases gradually as the Sn content increases. However, iron loss remains low compared to a steel without Sn, even if Sn is added up to 1400 ppm.

The Difference of effect on iron loss by Sn and Sb can be understood as follows.

Since Sn has a smaller segregation coefficient than Sb, about twice the Sn is required as compared with Sb to suppress nitride formation by surface segregation of Sn. Therefore, the iron loss is reduced by the addition of Sn of 20 ppm or more. The required amount of addition, by which the iron loss due to a resistance effect by segregation of Sn to the grain is also about twice the Sb content, since Sn has a smaller segregation coefficient than Sb. Thus, the addition of 100 ppm or more of Sn allows the iron loss to increase slowly.

by virtue of From the above facts, the Sn content is set to 20 ppm or more and its cap will be economical defined as 1000 ppm. Taking into account the iron loss is the desirable one Content 20 ppm or more and 100 ppm or less, more preferably 30 ppm or more and 90 ppm or less.

As previously discussed, the mechanisms of Sb and Sn are suppression the nitride formation identical. Therefore, make a simultaneous addition from Sb and Sn it possible also a similar one suppression effect for the To obtain nitride formation. However, Sn should be in double Amount of the amount of Sb can be added so that Sn has the same efficiency as Sb can show. Consequently, the amount of (Sb + Sn / 2) should be 0.001% or more and 0.05% or less, more desirably 0.001% or more and 0.005% or less when Sb and Sn are added simultaneously become.

In order to examine the optical grain diameter of the steel having a composition system according to the present invention, a steel having the composition of 0.0026% C, 2.65% Si, 0.18% Mn, 0.01% P, 0 was used , 30% Al, 0.0004% S, 0.0015% N and 0.004% Sb melted in vacuo, followed by washing with an acid solution after hot rolling. The hot rolled sheet was then annealed in an atmosphere of 75 H ₂ -25% N ₂ for 3 hours at 830 ° C, followed by cold rolling to a thickness of 0.35 mm. By applying a finish rolling in an atmosphere of 10% H ₂ -90% N ₂ at 705 to 1100 ° C for 2 minutes, the crystal grains can be greatly changed after finish rolling.

22 shows the relationship between the average crystal _{grain diameter} and iron _loss W _15/50 and W _10/400 . Out 22 It can be understood that the iron _{loss value} W _{15/50 is} rapidly increased at a frequency of 50 Hz when the average grain diameter is less than 70 μm, while the iron _{loss value} W _{10/400 is} rapidly increased at a frequency of 400 Hz when the mean grain diameter exceeds 200 microns. According to this result, the average crystal grain diameter of the sheet is limited to 70 to 200 μm in the present invention. It is more preferable to limit the mean crystal grain diameter to 100 to 180 μm.

(The reason why the Contents of other components are limited)

following This is the reason why the levels of other components are limited should be described.

Of the C content became 0.005% or less because of magnetic aging limited.

There Si is an effective element for increasing the self-resistance of the Sheet is added in an amount of 1.5% or more. On the other hand, the upper limit of the Si content was limited to 3.0%. as the magnetic flux density decreases with the saturation of the magnetic flux density decreases if its salary exceeds 3.0%.

Around a redbrittleness while of hot rolling To prevent more than 0.05% Mn are necessary. Because the magnetic Flux density, however, reduced at the Mn content of 1.5% or more its range is limited to 0.05 to 1.5%.

Although P is an element that is used to improve the Stan properties of the Sheet is required, its content was 0.2% or less limited, since an addition of more than 0.2% makes the sheet brittle.

There a big Amount of N pre-precipitate an amount of AlN leaves, if AlN grains get bigger, can become the grains do not develop well and the self-loss increases. Therefore was its content is limited to 0.005% or less.

Fine AlN grains formed during the addition of a trace amount of Al tend to degrade the magnetic properties. Therefore, its limit should be 0.1% or less to make the AlN grains coarser. On the other hand, the upper limit is set to 1.0% or less because the magnetic flux density is reduced at an Al content of 1.0% or more. If, however, the Amount of (Si + Al) exceeds 3.5%, the magnetic flux density decreases as the magnetizing current increases, so that the value of (Si + Al) is limited to 3.5% or less.

(Production method)

conventional Process for the production of the electromagnetic sheet can in be applied to the present invention, provided that the contents of S, Sb and Sn are in a given range. Of the Purified in a converter Steel is degassed to set to a prescribed composition whereupon he is pouring and hot rolling is subjected. The termination tempering temperature and the coiling temperature at hot rolling are not necessarily prescribed, but the temperature can be in a normal temperature range for producing a conventional temperature range electromagnetic sheet lie. A tempering or annealing after the hot rolling is not essential, although not prohibited. After forms of Steel to a sheet of a prescribed thickness by a Cold rolling or by two or more cold rolling operations with In between an intervening tempering, the sheet metal is about to be finished subjected. The crystal grain diameter prescribed in the present invention Can be achieved by the temperature of the final annealing is varied.

example

A steel shown in Table 10 was melted after adjusting it to a given composition by using a post-purge degassing treatment in the converter. The steel was hot rolled to a sheet thickness of 2.0 mm after heating the sheet at a temperature of 1150 ° C for 1 hour. The final temperature and coiling temperature were 750 ° C and 610 ° C, respectively. Then, this hot-rolled sheet was washed with an acid solution, followed by hot rolling and tempering under the conditions shown in Table 11 and Table 12. The atmosphere of hot rolling and annealing was 75% H ₂ -25% N ₂ . Then, the sheet was cold-rolled to a thickness of 0.1 to 0.5 mm and finally subjected to annealing under the final annealing conditions shown in Table 11 and Table 12. The final tempering atmosphere was 10% H ₂ -90% N ₂ .

The Magnetic measurement was carried out using a 25 cm Epstein test piece ((L + C) / 2). The magnetic characteristics of each sheet are shown in Table 10 to 12 listed together. The attached sheet metal numbers are in table 10 to 12 alike.

As can be seen in Tables 10 to 12, the thickness of the sheets Nos. 1 to 31, Nos. 32 to 35 and Nos. 36 to 38 is 0.35 mm, 0.20 mm and 0.50, respectively mm. When the steel sheets having the same thickness of 0.35 mm are compared with each other, all of the sheets No. 1 to No. 16 in the examples of the present invention have low iron _{loss values} W _15/50 and W _10/400 .

On the other hand, the sheet No. 17 has a crystal _{grain diameter} which is less than the range of the present invention, so that the value of W _15/50 becomes higher as compared with the values of the steel of the present invention. Since the crystal _{grain diameter} in the sheet No. 18 is above the crystal _{grain diameter of} the range of the present invention, the iron _{loss value} W _{10/400 is higher} in comparison with the values of the steel of the present invention.

The S and (Sb + Sn / 2) contents in Sheet No. 19 are out of the range of the present invention, so that both iron _{loss values} W _15/50 and W _{10/400 are} high. In Sheet No. 20, the iron _{loss values} W _15/50 and W _{10/400 are} high because the (Sb + Sn / 2) content is out of the range of the present invention. Both values (Sb + Sn / 2) content and crystal grain diameter are out of the range of the present invention, whereby the iron _{loss values} W _15/50 and W _{10/400 are} high.

The iron _{loss values} W _15/50 and W _10/400 as well as the magnetic flux density B ₅₀ are small in the sheet No. 22 because the (Si + Al) and (Sb + Sn / 2) contents are out of the range of the present invention lie. The sheet No. 23 has high iron _{loss values} W _15/50 and W _10/400 because the Si content is below the range of the present invention. Since the Si and (Si + Al) contents in the sheet No. 24 are over the range of the present invention, the iron _{loss values} W _15/50 and W _{10/400 are} low, but the magnetic flux density B ₅₀ is small. The sheet No. 25 also has low iron _{loss values} such as W _15/50 and W _10/400 , but a small magnetic flux density B ₅₀ because the (Si + Al) content exceeds the range of the present invention.

The sheet No. 26 has not only high iron _{loss values} W _15/50 and W _10/400 , but also a small magnetic flux density B ₅₀ , since the Al content and the crystal _{grain diameter} outside the range of underlying invention. Both the Al content and the (Si + Al) content are out of the range of the present invention in the sheet No. 27, so that the iron _{loss values} W _15/50 and W _{10/400 are} low, but the magnetic flux density B ₅₀ is is small. Sheet No. 28 has high iron _{loss values} W _15/50 and W _10/400 because the crystal _{grain diameter is} out of the range of the present invention. The sheet also has a problem of red brittleness during hot rolling because its Mn content is below the range of the present invention. The magnetic flux density B ₅₀ in the sheet No. 29 is small because the Mn content is more than the range of the present invention.

The crystal _{grain diameter of} the sheet No. 30 is out of the range of the present invention, thereby the iron _{loss values} W _15/50 and W _{10/400 are} high. This sheet has the problem of magnetic aging since the C content is also outside the scope of the present invention. The iron loss values W _15/50 and WT 10/400 of the sheet No. 31 are high because the N content and the crystal grain diameter are out of the range of the present invention.

For the sheets having a thickness of 0.20 mm, the sheet _metals Nos. 32 and 33 according to the present invention have lower iron _{loss values} W _15/50 and W _10/400 when compared with the comparison _sheets Nos. 34 and 35. The S and (Sb + Sn / 2) contents in Sheet No. 35 are out of the range of the present invention, so that the iron _{loss values} W _15/50 and W _{10/400 become} high.

All sheets Nos. 36 to 38, which have a thickness of 0.5 mm, have high iron _{loss values} W _15/50 and W _10/400 .

Table 10

Embodiment 5

Of the crucial point of this embodiment The present invention is to reduce the S content in an electromagnetic Sheet with a prescribed composition and a sheet thickness from 0.1 to 0.35 mm along with a reduction in high frequency iron loss reduce by adding Sb and Sn.

The above-described problem can be solved by an electromagnetic steel sheet having a thickness of 0.1 to 0.35 mm and a low iron loss in the high frequency region, in wt .-% 0.005% or less C, more than 3.0% and 4.5% or less Si, 0.05 to 1 , 5 wt% Mn, 0.2% or less P, 0.005% or less N, 0.1 to 1.5% Al, 4.5% or less Si + Al, 0.001% or less S and 0.001 to Containing 0.05% Sb + Sn / 2 with a balance of Fe and unavoidable impurities.

Besides, too lower loss values can be obtained by the (Sb + Sn / 2) content is limited to the range of 0.001 to 0.005%.

In the description of the present invention refers to "%" and "ppm", which represent the composition of the sheet, to "wt .-%" or "ppm by weight", if nothing else is specified.

(The reason why the S content is limited)

Around to investigate the effect of S-content on iron loss melted the researchers of the present invention first a steel with the Composition 0.0015% C, 3.51% Si, 0.18% Mn, 0.01% P, 0.50% Al and 0.0020% N with a varying amount of S of a trace amount to 40 ppm in the laboratory in vacuo, followed by washing with a Acid solution after a hot rolling.

The hot rolled sheet was then annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours, cold rolled to a sheet thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 950 ° C for 2 minutes. The magnetic properties were measured by a 25 cm Epstein method. The iron _{loss was} judged by W _10/400 because electrical equipment operated in a high frequency region of about 400 Hz can be magnetized to about 1.0 T.

The relationship between the S content of the material having a thickness of 0.35 mm and the iron loss is in 23 shown. Out 23 It can be seen that the iron _loss W _{10/400 is greatly reduced} at a frequency of 400 Hz in the material having a thickness of 0.35 mm when the S content is 10 ppm or less. To investigate the reason for this loss of iron due to the decrease in C content, the texture of the material was observed under an optical microscope. The result showed that crystal grains were coarser when the S content was 0.001% or less. The reason is likely that the MnS content in the steel has decreased.

It It is generally accepted that iron loss at high frequencies elevated is when the crystal grains in electromagnetic steel with a thickness of 0.5 mm are coarser. In the present experiment, however, the iron loss in High frequency regions are reduced with a coarsening of the crystal grains. These The fact can be understood that the eddy current loss in sheet steel with a thickness of 0.35 mm compared to that of Steel sheet with 0.5 mm thickness was greatly reduced as a decrease effective at hysteresis loss due to coarsening of the crystal grains contributes to the reduction of iron loss in high frequency regions, even when the frequency is 400 Hz.

Out The preceding discussions can be concluded that a Reduction of the S-content in the sheet metal with a thickness of 0.35 mm effective for reducing iron loss at high frequencies is. Consequently, the S content in the present invention becomes Limited to 10 ppm or less.

(The reason why the Sheet thickness is limited)

A Reduction in radiofrequency iron loss with the reduced S content is accompanied in the electromagnetic sheet with a Thickness of 0.35 mm or less proved as the sheet thickness became thinner. However, since the cold rolling in the sheet with a thickness of 0.1 mm or less, associated with a burden of customers with a lot Work to laminate the steel sheets would be difficult the sheet thickness in the present invention is 0.1 to 0.35 mm established.

The Methods for reducing high frequency iron loss were further investigated.

(The reason why the Sb and Sn contents are limited)

Increasing the Si and Al contents while increasing the self-resistance is usually effective for reducing the high frequency iron loss. However, if the content of Si + Al is more than 4.5%, cold rolling becomes difficult because the sheet becomes brittle, so that only by using the methods for increasing the Si and Al contents, the limit to iron loss reduction quickly approaches worked becomes. Therefore, researchers of the present invention sought some methods of reducing iron loss by adding quite different elements into the component.

As in 23 As can be seen, the iron loss has a slight decrease when the S content is 10 ppm or less, finally reaching an iron loss of only about 16.5 W / kg, provided that the S content is further reduced.

Based on the idea of the inventor that a decrease in iron loss in the material with a trace amount of S of 10 ppm or less be hampered by some unknown factors other than MnS could, the texture of the material was viewed under an optical microscope causing the steel surface layer in the range of S-content of 10 ppm or less, significant nitride layers were found. The nitride layer was in the S-content region of less than 10 ppm rare. This nitride layer could be during the annealing of the hot rolled Sheet metal and while of the graduation event.

Of the reason for an acceleration of the nitride formation reaction with decrease of the S content is assumed as follows. Since S is an element that is easy on the surface and is concentrated at grain boundaries, it is at the sheet surface in the S-content region of more than 10 ppm with suppression of Nitrogen absorption during focused on starting. In the S-content region of 10 ppm or On the other hand, less can suppress the effect of nitrogen absorption, which is attributed to S, worsened.

The Researchers expected that the nitride layer, which is predominantly in the material with a trace amount of S is formed in the reduction disturb the iron loss could. Based on this concept, the researchers had the idea that The iron loss could be further reduced if some elements that are capable to suppress and not prevent nitrogen absorption that the crystal grains develop well, be added. Through intensive studies found the researchers that an addition of Sb and Sn is effective.

The sample obtained by adding 40 ppm of Sb to the in 23 was prepared under the same conditions as those in the preceding examples. The results are in 24 shown. The following explains the effect of reducing iron loss. Although the iron loss is reduced by only about 0.2 to 0.3 W / kg in the S-content region of more than 10 ppm by adding Sb, the value is reduced by 1.0 W / kg by adding Sb, which shows a remarkable effect of Sb on the reduction of iron loss when the S content is small. No nitride layers were observed in this sample regardless of the S content. These results suggest that Sb is concentrated in the surface layer of the sheet while suppressing nitrogen absorption.

The The above discussions show that adding Sb in the material with a trace amount of S at a sheet thickness of 0.35 mm it is clear possible makes it possible to greatly reduce iron loss in high frequency regions.

To investigate the optimum amount of Sb added, a steel having the composition 0.0023% C, 3.51% Si, 0.30% Mn, 0.02% P, 0.50% Al, 0.0004% S and 0.0015% N with a varying amount of Sb from one trace to 700 ppm in the laboratory under vacuum, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was tempered in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 950 ° C for 2 minutes.

25 _Fig . ₁₄ shows the relationship between the Sb content of the sample thus obtained and the iron _loss W _10/400 . Out 25 For example, it can be understood that the iron _loss in the Sb _{content region} decreases from 20 ppm, where W _{reaches 10/400} 15.5 W / kg. If the Sb content is further increased to 50 ppm or more, the iron loss gradually increases as the Sb content increases.

Around the reason for the iron loss increase in the Sb content region of 50 ppm or To investigate more, the texture of the material was under one looking at the optical microscope, it has been found that although no nitride layers were detected, the middle one Crystal grain diameter had become slightly smaller. The reason is probably, although this is not certain that the grains are due of the grain boundary resistance effect of Sb could not grow well.

Indeed remains the iron loss of the sheet compared to the bleach, the contains no Sb, low, even if Sb is added in an amount of 700 ppm.

Out From these results, the Sb content was defined as 10 ppm and its Upper limit was 500 in economic terms ppm limited. Considering the iron loss values should be 10 ppm or more and 50 ppm or less, more desirable 20 ppm or more and 40 ppm or less.

Since Sn as well as Sb is also an element that can easily segregate at grain boundaries, the same effect for suppression of nitride formation can be expected. In order to investigate the optimum addition amount of Sn, a steel having the composition 0.0020% C, 3.00% Si, 0.20% Mn, 0.02% P, 1.05% Al, 0.0003% S was used and 0.0015% N was melted in the laboratory with a varying amount of Sn from a trace amount to 1400 ppm in vacuum, followed by washing with an acid solution after hot rolling. Subsequently, this hot-rolled sheet was annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. The sheet was cold rolled to a thickness of 0.35 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 950 ° C for 2 minutes.

26 _Fig . ₁₄ shows the relationship between the Sn content of the sample thus obtained and the iron _loss W _10/400 . Out 26 It is understood that the iron loss in the Sn _{content region} decreases by 20 ppm or more, whereby a iron _{loss value} W _10/400 of 5.5 W / kg is achieved. However, if the Sn content is further increased to more than 100 ppm, the iron loss gradually increases as the Sn content increases. However, the iron loss remains lower than that of the steel without Sn, even if Sn is added in a concentration of 1400 ppm.

Of the Difference of effect between Sn and Sb can be recognized as follows become.

There Sn has a smaller segregation coefficient than Sb, the about twice the amount of Sn compared to Sb to suppress one Nitride formation by surface segregation needed by Sn. Therefore, the iron loss by adding Sn at 20 ppm or more reduced. The required additional amount through which the Iron loss due to segregation resistance effect Sn starts to increase at the grain boundaries, too twice the amount of Sb since Sn has a smaller segregation coefficient as Sb has. Consequently, an addition of 100 ppm or more allows Sn, that the iron loss slowly increases.

Out The facts described above, the Sn content is 20 ppm or more fixed, the upper limit in view of the economic capacity 1000 ppm. In terms of iron loss, the content is more desirable Way 20 ppm or more and 100 ppm or less, and more preferably 30 ppm or more and 90 ppm or less.

As previously discussed, the mechanism of Sb and Sn is to suppress the Nitride formation identical. Therefore, make a simultaneous addition of Sb and Sn it also possible a similar one suppression effect for the To obtain nitride formation. However, Sn should be in one twice so big Amount such as the amount of Sb added to make it possible that Sn shows the same effect as Sb. Consequently, the amount should be at (Sb + Sn / 2) 0.001% or more and 0.05% or less, more desirably 0.001% or more and 0.005% or less when Sb and Sn are simultaneously be added.

(The reason why the Content of the other elements is limited)

Of the C content is due to the problem of magnetic aging 0.005% or less.

There Si is an effective element for increasing the self-resistance of the Sheet metal, it is added in an amount of more than 3%. The On the other hand, the upper limit of the Si content was limited to 4.5%. because cold rolling becomes difficult when its content exceeds 4.5% is.

More than 0.05% Mn are needed around a red brittleness while of hot rolling to avoid. However, since the magnetic flux density in the Mn content was reduced by 1.5% or more, was his range limited to 0.05 to 1.5%.

Although P is an element required to improve the punching properties of the sheet, its content was limited to 0.2% or less because an addition of more than 0.2% makes the sheet brittle power.

There a big Amount of N a big one Precipitate amount of AlN leaves, can grains if A.N grains are coarser, do not develop well, and the iron loss increases. Therefore, its content was limited to 0.005% or less.

Fine AlN grains, which were formed by adding a trace amount of Al tend to degrade the magnetic properties. Therefore, should its lower limit should be 0.1% or less to make the AlN grains coarser close. On the other hand, the upper limit becomes 1.5% or less determined because the magnetic flux density at an Al content of 1.5% or more decreases.

If the amount of (Si + Al) exceeds 4.5%, Cold rolling becomes so difficult that the upper limit is set to 4.5% becomes.

(Production method)

conventional Process for the production of the electromagnetic sheet can in be applied to the present invention, provided that the content of S, Sb and Sn as well as the content of the prescribed Elements are in a given range. The molten steel, which purified in a converter was, is degassed, to a prescribed composition This is followed by a submission to a casting and a hot rolling. The final temperature and the coiling temperature at hot rolling are not necessarily prescribed, but may be in a normal Temperature range for the production of conventional electromagnetic Lying sheet. An annealing or tempering after hot rolling is not essential, if not prohibited. After forming the Steel to a sheet of a prescribed thickness by a Cold rolling or two or more cold rolling operations with one interposed annealing The sheet is subjected to a final tempering.

example

It a steel shown in Table 13 was used, which became steel after adjustment to a given composition by application subjected to a degassing treatment after lautering in the converter pouring. The steel was heated at a temperature of 1150 ° C for 1 hour too hot-rolled to a thickness of 2.0 mm. The final temperature and the "coiling" temperature were 750 ° C or 610 ° C. Then this was hot rolled Washed sheet with an acid solution, followed by a hot rolling under annealing below those shown in Table 14 and Table 15 Conditions. Then, the sheet became to a thickness of 0.1 to 0.5 mm cold rolled and finally a final start under those indicated in Tables 14 and 15 Subject to conditions of closing. The numbers in Table 13, Table 14 and Table 15 indicate the plate number, which is the same under the tables.

The magnetic measurement was carried out using a 25 cm Epstein test piece. The magnetic characteristics of each sheet are listed in Table 14 and Table 15 together. The tempering temper of the cold rolled sheet was 75% H ₂ -25% N ₂ , while the final tempering grade was 75/10% H ₂ -90 / 5% N ₂ .

The sheet numbers 1 to 16 correspond to the sheet of the example according to the invention. In these examples, both iron _loss values, W _10/400 and W _{5 / lk, are} smaller than the corresponding values in the comparative examples _having the same sheet thickness.

In Comparative Example Sheet No. 17 has a very large iron loss, since the S and (Sb + Sn) contents are outside the range of the present Invention are.

Of the Iron loss in plate no. 18 is very large because of the (Sb + Sn) content and the sheet thickness outside of Area of the invention are.

Of the Iron loss in plate no. 19 is also great as its plate thickness outside within the scope of the present invention.

The S and (Sb; Sn) contents are in sheets no. 20 and no outside of the scope of the invention, whereby its iron loss values are greater than Sheet metal according to the present Invention are.

The Sheets # 22, # 23, and # 25 also have the (Sb + Sn) content outside of the scope of the present invention, so that their iron loss values greater than that of the sheets according to the present invention are, who have the same sheet thickness.

Of the Iron loss of sheet no. 26 is outside because of its Si content of the scope of the present invention.

The Si and (Si + Al) contents of plate no. 27 are above that Field of the present invention. Therefore, the steel could not be processed as a commercial product, since the sheet during the Rolling process broke.

The Sheet No. 28 has a lower Al content than the range of present invention, so that the iron loss is large.

Although the iron loss in the sheet No. 29 is small, the magnetic flux density B _{50 is} also small because the Al and (Si + Al) contents are over the range of the present invention.

The Plate No. 30 has a big one Iron loss, since the Mn content is within the scope of the present invention. on the other hand Iron loss is small, but the magnetic flux density is in steel No. 31 also small, since the Mn content is above the range of the present Invention is.

The Sheet metal No. 32 has except the problem of magnetic aging a high loss, since the C content above the Area of the present invention lies.

The Plate No. 33 has an N content that is above the range of the present Invention is such that the iron loss is large.

Table 13

Embodiment 6

Of the decision-making point of this embodiment The present invention is a non-oriented to obtain electromagnetic sheet with low iron loss, by reducing the amount of nitride on the surface of the sheet to a trace amount is suppressed after finishing tempering, on the Basis of the new discovery that, even if the S content on one Trace amount of 10 ppm or less is limited, the iron loss is not reduced, as a considerable nitride layer in the surface area in the composition area containing a trace amount of S becomes.

The above purpose can be achieved by a non-oriented electromagnetic sheet characterized by containing in wt% 4.0% or less C, 0.05 to 1.0% Mn, 0.1 to 1, 0% Al and Contains 0.001% S (inclusive of zero) with a considerable balance of Fe, and the nitride content within a range of 30 μm from the surface of the steel after termination tempering is 300 ppm or less.

(Process of the invention and the reason why the contents of S and nitride are limited)

To investigate the effect of 5 on iron loss, the researchers of the present invention have a steel having the composition 0.0025% C, 2.75% Si, 0.20% Mn, 0.010% P, 0.31% Al and 0.0018% N with a varying content of S from one trace to 15 ppm in the laboratory, followed by washing with an acid solution after hot rolling. This hot-rolled sheet was then annealed in an atmosphere of 75% H ₂ -25% N ₂ at 830 ° C for 3 hours. Then, the sheet was cold rolled to a thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 900 ° C for 2 minutes. The relationship between the S content of the sample and the iron _loss W _15/50 is in 27 shown (the symbol x in 27 ). The magnetic properties were measured using a 25 cm Epstein method.

Out 27 It is understood that a high degree of decrease in iron loss (W _15/50 = 2.5 W / kg) was achieved with a critical point at about S = 10 ppm when the S content was set to 10 ppm or less. The reason is that grains are well developed when the S content is decreased. Based on this result, the S content is limited to a range of 10 ppm or less and 5 ppm or more.

Indeed The rate of decrease of iron loss becomes slow when the S content is 10 ppm or less, making it impossible to lose iron under 2.4 W / kg.

Under assuming that a reduction in iron loss in the material, containing a trace amount of S of 10 ppm or less some other unknown factors than MnS could be inhibited considered the researchers of the present invention, the texture of the material under an optical microscope, where they show distinct nitride layers on the surface of the sheet in the region of S content of 10 ppm or less. In contrast, little nitride layers found in the S-content region of more than 10 ppm. These nitride layers can probably while the annealing of the hot rolled sheet and graduation, which is performed in a nitride-forming atmosphere.

Of the Reason why the nitride formation reaction with decrease of the S-content is accelerated is assumed as follows. Since S is an element, that on the surface and can be concentrated at grain boundaries, S is on the surface of the Concentrated steel in the S-content region of more than 10 ppm, whereby a nitrogen absorption from the atmosphere at the surface of the sheet metal during the tempering of the hot-pressed Sheet or while suppressed the final annealing becomes. Accordingly, little nitride layer can be formed, or she can do it at all not be formed. In the S-content region of 10 ppm or less On the other hand, the nitrogen absorption suppressing effect becomes in the S-content region of 10 ppm or less so reduced that on the steel surface some nitride layers are formed.

The Researchers hypothesized that the nitride layer contained in the S-grade region of 10 ppm or less is clearly formed, could prevent that crystal grains on the surface of the sheet develop well, causing a decrease in iron loss repressed becomes.

On At the basis of this concept, the researchers had the idea that the Iron loss of the material containing a trace amount of S, lowered could be if the nitride layer on the surface of the sheet to a given Area could be controlled.

28 Fig. 15 shows the relationship between the amount of nitride within a range of 30 μm from the surface of the sheet and W _15/50 . The nitrides were AlN, Si ₃ N ₄ and TiN. The range of 30 μm from the steel surface was described as 80 to 90% of the nitrides were within this range and they could rarely be found in the deeper region. Therefore, to judge the iron loss, it would be sufficient to determine the amount of nitride within the range of 30 μm from the steel surface.

28 shows that the iron loss is reduced when the nitride content within 30 μm from the steel surface is 300 ppm or less, whereby the iron loss value W _15/50 = 2.25 W / kg is achieved.

After the above result, the nitride content becomes within the range of 30 μm from the steel base area in the present invention is limited to 300 ppm or less.

(The reason why the Contents of other elements are limited)

sThe Reason why the contents of other components are limited should be described below.

Si: Si is an effective element for increasing the self-resistance of the Sheet, the upper limit of the Si content is limited to 4.0%, since the magnetic flux density decreases with the saturation the magnetic flux density decreases when its content exceeds 4.0%.

Mn: More than 0.05% Mn is needed about a redbrittleness while of hot rolling to prevent. Since the magnetic loss density at the Mn content of 1.0% or more, its range is limited to 0.05 to 1.0%.

al: Although Al like Si on for reinforcement the self-resistance is effective element, was the upper limit of the Al content is limited to 1.0%, as the magnetic flux density with the decrease in saturation the magnetic flux density decreases when its content exceeds 1.0%. The lower limit is set at 0.1% because AlN grains are added to the grains be fine to be well developed when the Al content less than 0.1%.

(Production method)

to Production of the electromagnetic sheet may be used in the present invention conventional methods are used, provided that the S content and the nitride content at the surface layer of the sheet in a given area. The molten steel, which purified in a converter was, is degassed to him on a prescribed composition then it becomes a pouring and a hot rolling subjected. The finishing temperature and the coiling temperature at hot rolling are not necessarily prescribed, but they can be a normal temperature range for producing a conventional act electromagnetic steel sheet. A tempering after the hot rolling is not essential, although it is not prohibited. After shaping of the steel to a sheet of a prescribed thickness a cold rolling process or by two or more cold rolling operations with an intermediate annealing, the sheet is a completion-tempering subjected.

The Method for adjusting the nitride content at the surface of the Sheet metal in a given area should not be specifically defined become.

Embodiment 7

Of the crucial point of this embodiment The present invention is a non-oriented to obtain electromagnetic sheet with a low iron loss, by the contents of S, Sb and Sn within a given range together with an optimization of the conditions of graduation be limited.

Of the Purpose may be due to a process of producing a non-oriented electromagnetic sheet, which is characterized is that a plate in wt .-% 0.005% or less C, 1.0 to 4.0% Si, 0.05 to 1.0% Mn, 0.2% or less P, 0.005% or less than N, 0.1 to 1.0% Al, 0.001% or less S and 0.001 to 0.05% (Sb + Sn / 2) with a substantial balance of Fe, after a hot rolling cold rolled, resulting in a finish rolling at a heating rate of 40 ° C / s or less follows. The heating rate, like here is used, refers to a mean heating rate of Room temperature to the soaking temperature. One the more preferable result is obtained by limiting the content of (Sb + Sn / 2) to a range of 0.001 to 0.005%.

Of the Expression "one significant balance of Fe ", as used herein means that the steel, the one Trace amount of other elements as unavoidable impurities be added in a range that has the effect of the present Invention not impaired, is within the scope of the present invention.

(Process of the invention and the reason why the levels of S, Sb and Sn and the conditions be limited to the graduation event)

The Researchers of the present inventors conducted a detailed study the factors for inhibiting iron loss reduction in the Material containing a trace amount of S of -10 ppm or less.

To investigate the effect of S on iron loss, first, a steel containing 0.0025% C, 1.65% Si, 0.20% Mn, 0.01% P, 0.31% Al and 0.0021 % N with a varying amount of S from a trace amount to 15 ppm, melted in the laboratory. The plate was hot rolled and annealed in an atmosphere of 100% N ₂ at 950 ° C for 3 minutes, followed by cold rolling to a thickness of 0.5 mm after washing with an acid solution. The subsequent finish annealing was conducted in an atmosphere of annealing 10% H ₂ -90% N ₂ at a heating rate of 20 ° C / sec and a soaking temperature of 93 ° C for 2 minutes. The term heating rate, as used herein, refers to an average heating rate from room temperature to the soaking temperature.

29 Fig. ₁₄ shows the relationship between the S content of the sample thus obtained and the iron _loss W _15/50 (the symbol x in the figure). The magnetic properties were measured by a 25 cm Epstein method. Out 24 It can be seen that a high degree of reduction in iron loss occurs when the S content is 10 ppm or less, thereby obtaining a material of W _15/50 = 3.2 W / kg. The reason is that the grains were well grown by reducing the S content. For this reason, the S content in the present invention is limited to 10 ppm or less.

Indeed The rate of decline of iron loss becomes slow when the S content 10 ppm or less is what makes it impossible to lose iron below 3.1 W / kg.

Under assuming that a reduction in iron loss in the material, containing a trace amount of S of 10 ppm or less some other unknown factors than MnS could be inhibited considered the researchers of the present invention, the texture of the material under an optical microscope, where they show distinct nitride layers on the surface of the sheet in the region of the S content of 10 ppm or less. In contrast, few nitride layers were in the S-content region of found more than 10 ppm. These nitride layers can probably while of annealing or tempering the hot rolled Sheet metal and while final annealing performed in a nitride-forming atmosphere.

Of the Reason why the nitride formation reaction with decrease of the S-content has been accelerated is assumed as follows. Since S is an element That's easy on the surface and is concentrated at grain boundaries, S is at the surface of the Concentrated steel in the S-content region of more than 10 ppm, whereby a nitrogen absorption from the surface at the surface of Sheet metal during is suppressed by the graduation event. In the salary region of 10 ppm or less, on the other hand, is the nitrogen absorption suppressive Reduced effect in the S-content region of 10 ppm or less.

The Researchers hypothesized that the nitride layer was clearly in the S-content region of 10 ppm or less is formed could, that crystal grains on the surface of the sheet, whereby a decrease in iron loss is suppressed. Based on this concept, the researchers had the idea that the iron loss of the material containing a trace amount of S continues could be reduced if some elements that are capable are to suppress nitrogen absorption and do not prevent that crystal grains well in the material containing a trace amount of S added could become. By Intensive studies, the researchers found that the addition of a trace amount at Sb is effective.

The sample prepared by adding 40 ppm of Sb to the previously described sample labeled with an x symbol was tested under the same conditions and the results are in 29 represented by the symbol o. The effect of iron loss reduction by Sb is described. While the iron loss value decreases only by 0.02 to 0.04 W / kg when Sb is added in the S-content region of more than 10 ppm, the value decreases by 0.20 W / kg by adding Sb in the S-content. Content range of 10 ppm or less, showing an obvious iron loss reducing effect of Sb when the S content is low. No nitride layers were observed in this sample, regardless of the S content, probably due to concentrated Sb on the surface of the sheet during the final tempering heating process with suppression of nitrogen absorption.

To study the optimum amount of Sb added, a steel was melted in the laboratory containing 0.0026% C, 1.60% Si, 0.20% Mn, 0.020% P, 0.30% Al, 0.0004% S and 0.0020% N with a varying amount of Sb from a trace amount to 130 ppm. The plate was hot rolled and tempered in an atmosphere of 100% N ₂ at 950 ° C for 3 minutes, followed by cold rolling to a thickness of 0.5 mm after washing with an acid solution. The subsequent finish annealing was performed in an annealing atmosphere of 10% H ₂ -90% N ₂ at a heating rate of 20 ° C / s and a soaking temperature of 93 ° C for 2 minutes.

30 shows the relationship between the Sb content and the iron _loss W _15/50 . It can be understood that the iron loss in the Sb content region is reduced by 10 ppm or more. However, the iron loss is reduced again when Sb is further added to a Sb content of more than 50 ppm.

It An observation was performed with an optical microscope to the reason of iron loss increase in the Sb content region of more than 50 ppm. The result showed that, although none Texture of a fine-grained surface layer was observed, the mean crystal grain diameter slightly smaller was done. Because Sb is an element that easily bonds to grain boundaries grains, although not sure, due to the grain boundary resistance effect not developed well by Sb.

Indeed The iron loss remains low compared to the steel Sb itself when Sb is added to a concentration of 700 ppm. To from the above results, the Sb content is set to 10 ppm or more, its upper limit from an economic point of view 500 ppm is.

It the same was the iron loss-reducing effect as Sb too observed, if Sn, in similar Make an element that easily segregates on the surface in a concentration of 20 ppm or more was added. However, in comparison to maintain a lower iron loss to the steel without Sn, even if Sn is added up to 1400 ppm. Accordingly, will the Sn content is set to 20 ppm or more, with the upper limit from an economic point of view is 1000 ppm. With regard the iron loss is its content to the region of 20 ppm or more and 100 ppm or less limited.

If Sb and Sn were added simultaneously, the iron loss decreased in the region of (Sb + Sn / 2) content of 10 ppm or more, with a significant increase in iron loss when 50 ppm or more (Sb + Sn / 2) were added.

One lower iron loss value compared to that of the sheet without Sb and Sn became at a (Sb + Sn / 2) level of 700 ppm or less reached. As a result, the (Sb + Sn / 2) content became the simultaneous addition set by Sb and Sn to 10 ppm or more, and its upper limit was limited to 500 ppm for economic reasons. In terms of iron loss is the desirable concentration 10 ppm or more and 50 ppm or less.

To study the optimum conditions of final tempering, a steel having the composition 0.0026% C, 1.62% Si, 0.20% Mn, 0.010% P, 0.0004% S, 0.0020% N was used and 0.004% Sb in a vacuum in the laboratory. After hot rolling, the sheet was annealed in an atmosphere of 100% H ₂ at 950 ° C for 5 minutes, followed by cold rolling to a thickness of 0.5 mm after acid washing. Finishing temper was changed by varying the heating rate variously up to a temperature of 930 ° C, and the sheet was cooled in the air after soaking for 2 minutes. The atmosphere of the final annealing was 10% H ₂ -90% N ₂ .

31 _Fig . ₁₄ shows the relationship between the heating rate at final tempering and the iron _loss W _15/50 . Out 31 it becomes clear that the iron loss in the range of the heating rate of more than 40 ° C / s increases. An observation of the texture of this sample showed that nitride formation was observed on the surface layer of the sheet in the sample, which was noted at a heating rate of more than 40 ° C / sec, although Sb was added.

The above-described phenomenon can be explained by the fact that the nitriding-suppressing effect of Sb for preventing nitridation could not be fully exhibited when the heating rate was high because the sheet was exposed to a high-temperature atmosphere before Sb became on the surface of the Sb Had set off steel when the heating rate was high. As a result, the heating speed at final tempering becomes 40 ° C / sec or less, desirably 25 ° C / sec or less ger with regard to iron loss.

(The reason why the Contents of other elements are limited)

Of the Reason why the contents of other components are limited should be described below.

C: Since C involves the problem of magnetic aging, it will be Salary limited to 0.005% or less.

Si: Since you have one to increase the self-resistance of the sheet is an effective element, is 1.0% or more Si added. The upper limit of the Si content becomes 4.0% limited as the magnetic flux density decreases with saturation the magnetic flux density is lowered when its content exceeds 4.0%.

Mn: Although 0.05% or more Mn for preventing red brittleness while Hot rolling required is, its content was limited to 0.05 to 1.0%, as the magnetic Flux density is reduced at a Mn content of 1.0% or more.

P: Although P is an element that improves the punching applicability sheet is essential, its content was 0.2% or less limited, as an addition of over 0.2% the sheet brittle power.

N: Since the magnetic flux density is reduced with a larger N content, its range is limited to 0.005% or less.

al: Although Al like Si one for the increase the self-resistance is effective element, was the upper limit of the Al content is limited to 1.0%, as the magnetic flux density with decrease in the saturation of the magnetic flux density is reduced when its content exceeds 1.0. The lower limit is determined to be 0.1% because AlN grains too fine for the grains to develop well if the Al content is less than 0.1%.

(Production method)

to Production of the electromagnetic sheet may be used in the present invention conventional methods be applied, provided that the contents of S, Sb and Sn and the heating rate at final tempering in a given Area are. The molten steel, which was purified in a converter, is degassed to adjust to a prescribed composition followed by submission to pouring and hot rolling. The final treatment temperature and the "coiling" temperature at hot rolling are not necessarily prescribed, but they can be a usual Temperature range for producing a conventional electromagnetic Tin trade. Tempering after hot rolling is not essential, although not prohibited. After washing with an acid solution and Forming the steel into a sheet of a prescribed thickness by a cold rolling process or by two or more cold rolling operations with an intervening glow or tempering, the steel sheet is a completion-tempering at a Heating rate of 40 ° C / s or less subject.

example

The in 19 The steel shown was used and the molten steel, which had been refined in a converter, is degassed to adjust to a prescribed composition, then subjected to casting and hot rolling. After heating the plate at 1140 ° C for 1 hour, the sheet was hot rolled to a sheet thickness of 2.3 mm. The finish tempering temperature for the hot rolled sheet was 800 ° C. The coiling temperature was 610 ° C when the hot rolled sheet annealed under the conditions shown in Table 17. After washing with an acid solution and cold rolling, the sheet was subjected to finishing tempering under the in 17 subjected to conditions shown. The atmosphere of annealing the hot rolled sheet and the atmosphere of final annealing were 100% H ₂ and 10% H ₂ -90% N _2, respectively. The term "heating rate" as used in Table 17 refers to the average heating rate from room temperature to the soaking temperature during final tempering. The magnetic properties were measured using a 25 cm Epstein test piece. The magnetic characteristics are also listed in Table 17. The numbers in Table 16 and Table 17 correspond to each other.

Out Table 16 and Table 17 is to be understood that a sheet with a Very low iron loss after finish tempering at the Steel according to the present Invention can be obtained in which the component of the steel controlled to the S, Sb and Sn contents of the present invention and the rate of heating or finish speed was adjusted to the range of the present.

On the other hand, the iron _loss W _15/50 is low in the steel sheet No. 12 because the contents of S and (Sb + Sn / 2) are out of the range of the present invention.

Sheets Nos. 14 and 15 have lower iron _{loss values} W _15/50 than sheets Nos. 12 and 13, but higher iron _{loss values} W _15/50 than that of the present invention, since the heating rate at final tempering is outside the scope of the present invention.

The sheet No. 16 not only has a high iron _loss W _15/50 , but also involves the problem of magnetic aging because the C content exceeds the range of the present invention.

Although the iron _loss W _{15/50 is} low, the plate No. 17 has a low magnetic flux density B ₅₀ because the Si content exceeds the range of the present invention.

Since the Mn content is lower than the range of the present invention, the iron _loss W _15/50 in the sheet No. 18 is high. In the sheet No. 19, the iron _loss W _{15/50 is} low, but the magnetic flux density B ₅₀ is also low because the Mn content is more than the range of the present invention.

The N content in the sheet No. 20 is over the range of the present invention, so that the iron _loss W _{15/50 is} high.

The Al content in the sheet No. 21 is below the range of the present invention, whereby the iron _loss W _{15/50 is} high. In the sheet No. 22, on the other hand, the Al content is over the range of the present invention, whereby the iron _loss W _{15/50 is} low and also has a low magnetic flux density B ₅₀ .

Table 16

Embodiment 8

Of the crucial point of this embodiment The present invention is to reduce the iron loss of a non-oriented electromagnetic sheet in the material that contains a trace amount of S of 10 ppm or less, by adding 0.03 to 0.15% P or at least one of Sb and Sn in one combined amount of (Sb + Sn / 2) in a range of 0.001 to 0.05% are included and the tempering temperature during one continuous final annealing and while controlled the "soaking" time becomes.

The first means for solving the above-mentioned problem includes a method of producing a non-oriented electromagnetic iron sheet having a low iron loss, characterized by the steps of hot-rolling a sheet comprising, by weight, 0.005% or less C, 1.5 to 3 , 5% Si, 0.05 to 1.0% Mn, 0.005% or less (including zero) N, 0.1 to 1.0% Al, 0.001% or less (inclusive of zero) S and 0.03 to 0 , 15% P with a substantial amount of Fe; Forming a sheet of a given thickness by a cold rolling operation or two or more cold rolling operations with annealing therebetween after annealing the hot rolled sheet, if necessary; and subjecting a finish annealing in an atmosphere having an H ₂ concentration of 10% or more for a soaking time of 30 seconds to 5 minutes.

The second means for solving the above-mentioned problem comprises a method for producing a non-oriented electromagnetic iron sheet with low iron loss, characterized by the steps of: hot rolling a plate comprising in wt% 0.005% or less C, 1.5 to 3 , 5% Si, 0.05 to 1.0% Mn, 0.005% or less (inclusive of zero) N, 0.1 to 1.0% Al, 0.001% or less (inclusive of zero) S and at least one of Sb and Sn in a combined amount of (Sb + Sn / 2) in the range of 0.001 to 0.05% with a substantial amount of Fe; Forming a sheet of a given thickness by a cold rolling operation or two or more cold rolling operations with annealing therebetween after annealing the hot rolled sheet, if necessary, and subjecting to finish tempering in an atmosphere having an H ₂ concentration of 10 % or more for a soaking time of 30 seconds to 5 minutes.

The third means of solution The above-mentioned problem includes a method of production a non-oriented Electromagnetic sheet with low iron loss, characterized through the steps of hot rolling a plate comprising, in% by weight, 0.005% or less C, 1.5 to 3.5% Si, 0.05 to 1.0% Mn, 0.005% or less (including zero) N, 0.1 to 1.0% Al, 0.001% or less (including zero) S, 0.03 to 0.15% P and at least one of Sb and Sn in one combined amount of (Sb + Sn / 2) in a range of 0.001 to 0.05% with a balance of Fe and unavoidable impurities; Forming a sheet of a given thickness by a cold rolling process or two or more cold rolling operations with an intervening annealing after one Tempering the hot rolled Sheet metal if required; and subject to a graduation-tempering in an atmosphere from 10% or more for a "soaking" time of 30 seconds to 5 minutes.

The fourth means of solution of the above problem includes a non-oriented one Electromagnetic sheet passing through one of the first to third Media was produced or a non-oriented electromagnetic Sheet with a low iron loss that is identical to it.

In The following descriptions refer to "%" and "ppm" which indicate the composition of the steel, to "% by weight" or "ppm by weight".

(Process of the invention and the reason why the contents of S and the conditions of tempering be limited)

The Researchers of the present invention conducted a detailed study of the Factors for reducing iron loss in the material that contains a trace amount of S in a range of 10 ppm or less. As a result, it was made clear that considerable nitride layers at the surface layer of the sheet were observed to decrease in S content and that this nitride layer prevented iron loss from being reduced has been.

The Researchers led intensive studies about Method of suppression nitride film formation to further reduce iron loss; They discovered that the iron loss of the material, the contains a trace amount of S, in big Extent can be reduced by the material 0.03 to 0.15% P or at least one of Sb and Sn in a combined amount of (Sb + Sn / 2) in a range of 0.001 to 0.05% was, and at the same time the atmosphere of tempering during the continuous Final event and "soaking" time has been.

The The present invention will be described in more detail below with reference to FIGS experimental results are described.

• (1) C: 0,0025%, Si: 1,85%, Mn: 0,20%, P: 0,040%, Al: 0,31%, N: 0,0018%
• (2) C: 0,0025%, Si: 1,85%; Mn: 0,20%, P: 0,010%; Al: 0,31%, N: 0,0018%, Sn: 0,0050%
• (3) C: 0,0025%, Si: 1,85%, Mn: 0,20%, P: 0,010%, Al: 0,31%, N: 0,018%, Sb: 0,0040%

For the purpose of examining the effect of the S content on iron loss, the steels having the composition systems given below in (1), (2) and (3) were varied with a varying amount Concentration of S ranging from a trace amount to 15 ppm in vacuum, followed by washing with an acid solution. The obtained hot-rolled sheets were tempered in an atmosphere of 75% H ₂ -15% N ₂ at 800 ° C for 3 hours. Subsequently, the sheet was rolled to a thickness of 0.5 mm, followed by finish annealing at 900 ° C by three kinds of combination of the tempering atmosphere and the soaking temperature.

• (1) C: 0.0025%, Si: 1.85%, Mn: 0.20%, P: 0.040%, Al: 0.31%, N: 0.0018%
• (2) C: 0.0025%, Si: 1.85%; Mn: 0.20%, P: 0.010%; Al: 0.31%, N: 0.0018%, Sn: 0.0050%
• (3) C: 0.0025%, Si: 1.85%, Mn: 0.20%, P: 0.010%, Al: 0.31%, N: 0.018%, Sb: 0.0040%

32 _Fig . ₁₅ shows the relationship between the S content of the sample thus obtained and the iron _loss W _15/50 . Out 32 It can be seen that the iron loss is greatly reduced when the S content is 10 ppm or less, achieving a W _15/50 value of 2.5 W / kg. The reason is that by reducing the S content, grains are grown well. Although the S content in the present invention is limited to 10 ppm or less, the content is desirably 5 ppm or less.

However, it has been made clear that the decreasing level of iron loss at an S content of 10 ppm or less differs depending on the combination of the tempering atmosphere and the soaking time. In order to investigate the reasons why the decrease in the level of iron loss differs depending on the combination of the tempering atmosphere and the soaking time, the researchers observed the texture of the material under an optical microscope. The results showed that notable nitride layers were observed on the surface layer of the sheet at all three components systems when the combination of 5% H _2/2 minutes 'soaking "and 15% H _2/20 seconds'soaking." In contrast, 15% H were _2/2 determined few nitride layers minutes' soaking "in the combination. This nitride layer appears to be formed during annealing of the hot rolled sheet and finish annealing.

Of the Reason why a different nitride formation mechanism in dependence from the difference of the S content can be understood as follows become. Since S is an element that is easy on the surface and is concentrated at grain boundaries, S at the steel surface in the S-content region of more than 10 ppm with suppression of Nitrogen absorption during the graduation event. On the other hand, in the S-content region of 10 ppm or less of the nitrogen absorption suppressive effect reduced. Although a deterioration of this suppression effect was attempted to supplemented by controlling the levels of P or Sn to become, or by change the combination of the occasion atmosphere and the conditions of the Finish annealing (The atmosphere of the "soaking" time), there were some Differences in the nitrogen absorption suppressing ability through the combination atmosphere of the starting "soaking" time. These results were supposed to be something over to announce the iron loss level.

• (4) C: 0,0020%, Si: 1,87%, Mn: 0,20%, P: 0,040%, Al: 0,30%, S: 0,0003%, N: 0,0017%
• (5) C: 0,0020%, Si: 1,87%, Mn: 0,20%, P: 0,010%, Al: 0,31%, S: 0,0003%, N: 0,0017%, Sn: 0,0050%
• (6) C: 0,020%, Si: 1,87%, Mn: 0,20%, P: 0,010%, Al: 0,30%, S: 0,0003%, N: 0,0017%, Sb: 0,0040%

For the purpose of examining the optimum combination atmosphere of soaking time, the steels having the composition systems given in (4), (5) and (6) below were vacuum-fused, followed by washing with an acid solution after one The obtained hot-rolled sheets were subjected to tempering in an atmosphere of 75% H ₂ -15% N ₂ at 800 ° C for 3 hours, followed by cold-rolling the sheet to a thickness of 0.5 mm, followed by finishing. Tempering at 930 ° C by varying the combinations of tempering atmosphere and soaking temperature.

• (4) C: 0.0020%, Si: 1.87%, Mn: 0.20%, P: 0.040%, Al: 0.30%, S: 0.0003%, N: 0.0017%
• (5) C: 0.0020%, Si: 1.87%, Mn: 0.20%, P: 0.010%, Al: 0.31%, S: 0.0003%, N: 0.0017%, Sn: 0.0050%
• (6) C: 0.020%, Si: 1.87%, Mn: 0.20%, P: 0.010%, Al: 0.30%, S: 0.0003%, N: 0.0017%, Sb: 0.0040%

33 Fig. 14 shows the relationship between the finish-annealing time for each H ₂ concentration and the iron loss W _15/50 for each sample obtained. Out 33 It can be seen that the iron loss for each composition system in the range of H ₂ concentration of 10% or more and the final annealing annealing time of 30 seconds to 5 minutes is reduced, with an iron loss value W _15/50 of _2.5W / kg is reached. After this result, the H ₂ concentration of the atmosphere of the continuous finish annealing and the time of the equalizing annealing are defined as 10% or more and 30 seconds to 5 minutes, respectively.

(The reason why the other components are limited)

Of the Reason why the contents of other components are limited should be described below.

C: The C content is limited to 0.005% or less as the element the problem of magnetic aging is involved.

Si: Since Si is an effective element for increasing the self-resistance of the Sheet metal, its lower limit is defined as 1.5%. The upper limit The Si content is limited to 3.5% because of the magnetic flux density with decrease in saturation the magnetic flux density is reduced when its content exceeds 3.5%.

Mn: It is more than 0.05% Mn necessary to get a red brittleness while of hot rolling to prevent. However, since the magnetic flux density at the Mn content is reduced by 1.0% or more, its range is up 0.05 to 1.0% limited.

N: The content of N is limited to 0.005% or less, as a Amount of AlN under increase of iron loss precipitated, if a big one Amount of N is included.

al: Although Al and Si are an effective element for increasing the Is inherent resistance, the upper limit of the Al content has been increased to 1.0% limited as the magnetic flux density decreases with the saturation the magnetic flux density is lowered when its content exceeds 1.0%. The lower limit is determined to be 0.1% because AlN grains become too fine than that grains develop well if the Al content is less than 0.1%.

P: Since P has a nitrogen absorption during the annealing of the hot rolled Sheet metal and graduation tempering will be his salary with 0.03% or more and the upper limit is determined as a result of Problems of compatibility limited to 0.15% with cold rolling.

sb and Sn: Both, Sb and Sn, are effective elements for the suppression of Nitrogen absorption during the annealing of the hot rolled Bleeding and graduation-tempering, and Sb has one twice huge Effect like Sn. Consequently, the elements are combined in one Amount of (Sb + Sn / 2) in the range of 0.001% or more calmly. The upper limit is from an economic point of view 0.05%. Any of the elements P, Sb and Sn can be selective be included or all three elements can be included together.

(Production method)

In of the present invention conventional Method for producing the electromagnetic sheet, except the conditions for Continuous Termination (Termination) provided the prescribed components, including S, P, Sb and Sn are within a given range. The melted Steel, which has been refined in a converter, is degassed, to adjust to a prescribed composition, then becomes he's a casting and a hot rolling subjected. The temperature of the final annealing and the temperature Coiling during hot rolling are not necessarily prescribed, but may be in a normal Temperature range for producing a conventional electromagnetic Sheet lie. Tempering after hot rolling is not essential, though not forbidden. A continuous graduation start after forming the steel becomes a sheet with a prescribed Thickness through a cold rolling process or two or more cold rolling operations with an intervening glow applied.

example

The in 18 The steel shown was used and the molten steel, which had been refined in a converter, is degassed to adjust to a prescribed composition (the composition is expressed in weight%). The plate was hot rolled after heating the plate at a temperature of 1160 ° C for 1 hour to a sheet thickness of 2.0 mm, followed by casting and hot rolling. The finish tempering temperature of the hot rolled sheet was 800 ° C and the coiling temperature was 610 ° C. The hot-rolled sheet was annealed under the conditions shown in Table 19. The sheet was then cold rolled to a thickness of 0.5 mm, followed by tempering by the finish tempering conditions given in Table 19. The magnetic properties were measured using a 25 cm Epstein test piece. The magnetic characteristics are summarized in Table 19. Table 18 and Table 19 were originally a table, and the sheet numbers in each table are the same.

The Si content in the steel sheets No. 1 to No. 18 has a level of 1.8%, while the steel of the No. 19 to No. 26 sheets has a level of 2.5%. When sheets having the same Si level are compared with each other, the sheet of the present invention has a low iron _loss W _15/50 as compared with the comparative sheet.

The above results, when the contents of S, P and (Sb + Sn / 2), the addition amount of any of these elements, the annealing atmosphere during the continuous finish annealing, and the annealing time are all within the scope of the present invention , a non-oriented electromagnetic sheet having a very low iron loss after finish tempering can be obtained. It is also suggested that the magnetic flux density B _{50 was} not reduced in these non-oriented electromagnetic sheets.

On the other hand, sheets Nos. 9 and 22 have high iron _{loss values} W _15/50 because the S content is out of the range of the present invention.

The H ₂ concentration during the finish annealing at the plates Nos. 15 and 23 and the time for the equalizing annealing during the finish annealing at the plates Nos. 16, 17, 24 and 25 are out of the range the present invention; As a result, the iron _{loss values} W _{15/50 are} high.

The sheet No. 11 not only has a high iron _loss W _15/50 , but also involves a problem of magnetic aging because the C content exceeds the range of the present invention.

Since the Mn content in the steel sheet no. 12 exceeds the range of the present invention, the magnetic flux density B ₅₀ is low.

The Al content in the sheet No. 13 is below the range of the present invention, so that the iron _loss W _{15/50 is} high.

The iron _loss W _15/50 in the sheet No. 14 is high because the N content exceeds the range of the present invention.

The iron loss values W _{15/50 of} the sheets Nos. 18 and 26 are high because the P, Sn and Sb contents are out of the range of the present invention.

Although the iron loss value W _15/50 is controlled low, the sheet 27 and the magnetic flux density B ₅₀ is low because the Si content is higher than the range of the present invention.

Table 18

Table 19

Embodiment 9

Of the crucial point of this embodiment The present invention is the formation of nitrides for Reduce iron loss by suppressing the temperature of the occasion during the continuous closing and "soaking" time are monitored, new finding based that the iron loss is not reduced can be, even if the S content is limited to a trace amount of 10 ppm or less, as distinct Nitride layers on the surface in the region containing a trace amount of S are formed.

The above problem is solved by a method for producing a non-oriented electromagnetic sheet characterized in that it comprises the steps of: hot-rolling a plate in wt% of 0.005% or less C, less than 1.5 % Si, 0.05 to 1.0% Mn, 0.2% or less P, 0.005% or less (inclusive of zero) N, 0.1 to 1.0% Al, and 0.001% or less (inclusive of zero) S containing a balance of Fe and unavoidable impurities; Forming the hot rolled sheet into a sheet of a given thickness by cold rolling once or by cold rolling twice or more, with an intermediate annealing after annealing of the hot rolled sheet being interposed as required; and subjecting the cold-rolled sheet to a continuous discharge Final tempering in an atmosphere with an H ₂ concentration of 10% or more for a soaking time of 30 seconds to 5 minutes.

The above problem is also solved by a method of producing a non-oriented electromagnetic sheet characterized by comprising the steps of: hot-rolling a sheet in wt% of 0.005% or less C, less than 1, 5% Si, 0.05 to 1.0% Mn, 0.2% or less P, 0.005% or less (including zero) N, 0.1 to 1.0% Al, 0.001% or less (including zero) S, 0.001 to 0.05% (Sb + Sn / 2) containing a substantial amount of Fe; Forming the hot rolled sheet into a sheet of a given thickness by a cold rolling operation or two or more cold rolling operations with annealing annealed therebetween after tempering the hot rolled sheet, if necessary; and subjecting the cold-rolled sheet to continuous finish annealing in an atmosphere having an H ₂ concentration of 10% or more for a soaking time of 30 seconds to 5 minutes.

In In the following description, "% of steel component" and "ppm" refers to "% by weight" and "ppm by weight", respectively.

(Process of the invention and the reason why the S-content and the conditions of graduation ceremonies are limited become)

method The present invention will be described below in detail.

To study the effect of S on iron loss, first a steel containing 0.0020% C, 0.25% Si, 0.55% Mn, 0.11% P, 0.25% Al, 0.0018 % N and a trace amount of Sb having a varying amount of S from one trace to 15 ppm were melted in the laboratory, followed by washing with an acid solution after hot rolling. The hot rolled sheet was then cold rolled to a sheet thickness of 0.5 mm, finish tempered at 750 ° C with three kinds of combination annealing atmosphere and soaking time, and then tempered for 2 hours subjected to magnetic annealing in an atmosphere of 100% N ₂ at 750 ° C for 2 hours.

34 Fig. ₁₅ shows the relationship between the S content of the sample thus obtained and the iron _loss W _15/50 after the magnetic annealing. The magnetic properties were measured using a 25 cm Epstein test piece.

Out 34 It is apparent that the iron _loss W _{15/50 is} greatly reduced to 4.2 W / kg when the S content is 10 ppm or less. The reason for this is that the amount of the precipitated MnS is reduced by lowering the S content, whereby the ferrite grains are well developed. According to this result, the S content in the present invention is limited to 10 ppm or less.

However, it has also been made clear that the degree of reduction of iron loss at an S-content of 10 ppm or less depends on the combination atmosphere of annealing and tempering time. As in 34 is shown, the decrease in iron loss at the S-content of 10 ppm or less in the combination 15% H ₂ - 1 minute equalizing annealing is much greater than in the combination 5% H ₂ - 20 seconds equalizing annealing.

To study the cause of the above results, the researchers observed the texture of the steel under an optical microscope. Distinct nitride layers were found on the surface layer of the sheet in the combination 5% H ₂ - 1 minute soaking. On the other hand, the combination of 15% H ₂ - 1 minute equalizing annealing rarely found nitride layers. Consequently, these nitride layers appear to be formed by the magnetic equalizing annealing performed in an atmosphere of 100% N ₂ .

Of the Reason Why the Nitride Formation Reaction Shows Various Aspects can be explained as follows become. Since S is an element that is easy on the surface and is concentrated at grain boundaries, S was on the surface of the Concentrated steel in the S-content region of more than 10 ppm; As a result, the nitrogen absorption at the surface of the Sheet metal during of magnetic annealing of the hot rolled Sheet or while suppressed the final annealing. In the S-content region of 10 ppm or less, it was the nitrogen absorption suppressive Effect in the S-content region of 10 ppm or less so reduced that the reduced nitrogen absorption suppressing ability reflected in the degree of iron loss.

In order to investigate the range of the optimum combination atmosphere of annealing and soaking time, the steel having the composition 0.0021% C, 0.25% Si, 0.52% Mn, 0.100% P, 0.26% Al and 0.0015% N; and a steel melted by adding 0.0040% of Sb to the steel having the same composition in the laboratory, followed by acid washing after hot rolling. This hot rolled sheet was then cold rolled to a thickness of 0.5 mm and subjected to finish annealing at 750 ° C, changing the combinations of H ₂ concentration and annealing time, finally subjected to magnetic annealing in an atmosphere of 100% N ₂ subjected to 750 ° C for 2 hours.

35 Figure 12 shows the relationship between final tempering annealing time at each H ₂ concentration for each sample thus obtained and the iron loss W _15/50 . Out 35 It can be seen that the iron loss in the region of an H ₂ concentration of more than 10% and the compensation annealing time at final tempering was reduced from 30 seconds to 5 minutes, with a W iron loss value W _15/50 of 4.0 W / kg or less in each of the steels containing or not containing Sb.

It It also became clear that an addition of Sb and an optimal combination the annealing atmosphere and the soaking time the loss of iron decreases further than with the steel, the no Sb contains.

(The reason why the Contents of other elements are limited)

Of the Reason why the contents of other components are limited should be described below.

C: Since C involves a problem of magnetic aging, it would be Salary limited to 0.0005% or less.

Si: While Si one to increase The self-resistance of the sheet is an effective element, the upper limit of the Si content limited to 1.5%, since the magnetic flux density with the decrease in saturation the magnetic flux density decreases if its content is 1.5% or is more.

Mn: It takes more than 0.05% Mn, around a red brittleness while of hot rolling to prevent. As the magnetic flux density at the Mn content will be reduced by 1.0% or more, however, will be its range limited to 0.05 to 1.0%.

P: Although P is an element responsible for improving the punching applicability Sheet metal is essential, its content becomes 0,2% or less limited, because the sheet is fragile when P is greater than 0.2% is added.

N: Since a lot of AlN precipitates, if the Al content is below increase iron loss is big its range is limited to 0.005% or less.

al: Although Al like Si one for the increase the self-resistance element is effective, was the upper limit of the Al content is limited to 1.0%, as the magnetic flux density with the decrease in saturation the magnetic flux density decreases when its content exceeds 1.0%. The lower limit is set at 0.1% because AlN grains increase be finer than that the grains could develop well, when the Al content is less than 0.1%.

sb + Sn / 2: Although both elements, Sb and Sn, are equally related to effective suppression nitrite formation, Sb is twice as potent as Sn. Although a content of (Sb + Sn / 2) of 0.001% or more is preferred the nitride formation during of magnetic annealing to suppress, will raise its ceiling from an economic point of view 500 ppm limited. Either Sb or Sn is allowed, provided that (Sb + Sn / 2) remains within the range described above.

(Production method)

Conventional methods of producing the electromagnetic sheet can be applied in the present invention, provided that the contents of S and prescribed components are within a given range. The molten steel, which has been refined in a converter, is degassed to adjust to a prescribed composition, then subjected to casting and cold rolling. The temperature of the final annealing and the coiling temperature The uniform annealing temperature in hot rolling is not necessarily prescribed, but may be in a normal temperature range for producing a conventional electromagnetic sheet. Annealing after hot rolling is not essential, although it is not prohibited. After forming the steel into a sheet having a prescribed thickness by a cold rolling process or by two or more cold rolling operations with an intermediate annealing interposed therebetween, the sheet is subjected to finish annealing.

example

The steel shown in Table 20 was used, and the molten steel, which had been refined in a converter, was degassed to adjust to a prescribed composition, after which it was subjected to casting and hot rolling. After heating the plate at 1160 ° C for 1 hour, the sheet was hot rolled to a sheet thickness of 2.0 mm. The finish tempering temperature of the hot rolled sheet was 800 ° C, and the temperature of the equalizing annealing was 670 ° C. After washing with an acid solution and cold rolling this hot-rolled sheet to a thickness of 0.5 mm, the sheet was subjected to finish annealing under the conditions shown in Table 20, followed by magnetic annealing in an atmosphere of 100% N ₂ at 750 ° C for 2 hours. The magnetic properties were measured using a 25 cm Epstein test piece. The magnetic characteristics are also listed in Table 20. The "retention time" given in Table 20 refers to "soaking" time.

The steel sheets Nos. 1 to 9 and Nos. 19 to 24 correspond to the examples of the present invention which have 0.25% of Si concentration and 0.75% of Si concentration, respectively. The iron _{loss values} W _15/50 are far lower than 4.2 W / kg, which is a concentration considered difficult to achieve in the conventional field, ranging from 3.84 to 4.00 W / kg in steels Reach Si concentrations of the order of 0.25% and up to 3.30 to 3.40 W / kg in steels with Si concentrations of the order of 0.75. In addition, the iron loss of the steel added with Sb is further reduced as compared with the steel containing no Sb.

The steels with an Si concentration in the order of 0.25% and the steel with a Si concentration of 0.75% also have high magnetic flux densities B ₅₀ of 1.76 T and 1.73 T.

On the other hand, the sheet No. 10 has a high iron _loss W _15/50 because the S content is out of the range of the present invention.

Crystal grains can not be well developed and the iron _loss W _15/50 becomes low in the sheet No. 11 because the Al content is lower than the range of the present invention.

Although the iron loss W _15/50 is reduced in the sheet No. 12, the magnetic flux density B _{50 is also} low because the Al content is higher than the range of the present invention.

The sheet No. 13 not only has a high iron _loss W _15/50 , but also involves the problem of magnetic aging due to a higher C content outside the range of the present invention.

Although the iron _loss W _15/50 is lowered in the plate No. 14, it is still higher than that of the steel of the present invention, but has a low B ₅₀ because the Mn content is out of the range of the present invention.

Sheet No. 15 has a high iron _loss W _15/50 because N is out of the range of the present invention.

The H ₂ concentration during the finish annealing of the sheet No. 16 and the equalizing annealing time during the finish annealing of the sheet No. 17 and No. 18 are respectively outside the range of the present invention, so that the iron _{loss values} W _{15/50 are} high are.

In the sheets having the Si concentration of 0.75%, the S content of the sheet No. 25 is out of the range of the present invention, so that the iron loss W _{15/50 is} higher than that of the sheet of the present invention having the same Si. Concentration is.

Since the H ₂ concentration during the finish annealing of the sheet No. 26 and the time of the equalizing annealing during the finish annealing of the sheet No. 27 and No. 28 are respectively outside the range of the present invention, the iron loss values W _{15 / 50} high.

Since the Si content in the sheet No. 29 is over the range of the present invention, the magnetic flux density B _{50 is} low, although the iron _loss W _{15/50 is} controlled in a low range.

As from the preceding examples and comparative examples can be a non-oriented electrostatic sheet, the one has very low iron loss after magnetic annealing and not a reduction in magnetic flux density suffers, by the concentrations of S and others prescribed components in the steel, the atmosphere during the continuous finish tempering and the equalization annealing time within of the scope of the present invention.

Embodiment 10

Of the crucial point of this embodiment The present invention is a non-oriented to produce electromagnetic sheet metal that has a low iron loss after finish tempering, by subtracting the S-content and the Sb- and Sn content to be prescribed to a given concentration as well as the conditions of tempering the hot rolled sheet suitable be set.

The The above problem can be solved by methods of preparation a non-oriented electromagnetic sheet to be solved including the steps: hot rolling a plate containing in% by weight 0.005% or less C, 1.5 to 4.0% Si, 0.5 to 1.0% Mn, 0.2% or less P, 0.005% or less N, 0.1 to 1.0% Al, 0.001% or less S and 0.001 to 0.05% (Sb + Sn / 2) with a balance of Fe and unavoidable impurities contains followed by a tempering and shaping to a non-oriented electromagnetic sheet metal over cold rolling and finish tempering characterized by Controlling the heating rate of the hot rolled sheet, the Tempering in a mixed atmosphere to hydrogen and nitrogen at 40 ° C / s or less becomes.

A Limiting the content of (Sb + Sn / 2) to a range of 0.001 to 0.005% allows the iron loss of a non-oriented electromagnetic sheet is further reduced.

"heating or heating rate during tempering of hot-rolled sheet "refers to an average heating rate from room temperature to a soaking temperature Temperature of equalizing annealing.

(Process of the invention and reason why the contents of Si, Sb and Sn are limited)

The Inventors of the present invention investigated the factors which a reduction in iron loss in the material, a trace amount at S of 10 ppm or less, disturb; this makes it clear that distinct nitride layers on the surface of the sheet with decrease of the S-content, which prevent the iron loss from reducing becomes.

By intensive studies about Method of suppression nitride formation to further reduce iron loss the researchers that the iron loss of a material that has a trace amount contains at S could be significantly reduced by combining Sb or Sn in a combined Amount of (Sb + Sn / 2) was added from 0.001 to 0.05% and simultaneously the conditions of tempering the hot rolled sheet suitable were set.

To investigate the effect of S on iron loss, a steel containing 0.0025% C, 1.65% Si, 0.20% Mn, 0.01% P, 0.31% Al, and 0.0021% was used. N with a varying amount of S from a trace amount to 15 ppm, melted in the laboratory, followed by washing with an acid solution after hot rolling. The hot-rolled sheet was annealed under conditions of an atmosphere of annealing 75% H ₂ -25% N ₂ , a heating rate of 1 ° C./s and a soaking temperature of 800 ° C. for 3 hours. The heating rate, as used herein, refers to an average heating rate from room temperature to the equalizing annealing temperature (hereinafter the same). The hot rolled sheet was then cold rolled to a thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ at 930 ° C for 2 minutes. 36 Fig. ₁₄ shows the relationship between the S content of the sample thus obtained and the iron _loss W _15/50 (the symbols x in the figure). The magnetic properties were measured by a 25 cm Epstein test.

Out 36 It is understood that the iron loss sharply decreases when the S content is set to 10 ppm or less, whereby an iron _{loss value} of W _15/50 = 3.2 W / kg is achieved. The reason is that the grains can develop well by reducing the S content. According to these results, the S content in the present invention is limited to 10 ppm or less.

On the other hand is a reduction in iron loss at an S content of 10 ppm or less slow, with iron loss only about 3.1 W / kg, even if the S content is further reduced.

Under assuming that a reduction in iron loss in the material, containing a trace amount of S of 10 ppm or less some other unknown factors than MnS could be inhibited considered the researchers of the present invention, the texture of the material under an optical microscope, with distinct nitride layers on the surface of the sheet in the region of S content of 10 ppm or less. In contrast, in the S-content region of more than 10 ppm, little became Nitride layers found. These nitride layers can probably while the annealing of the hot rolled sheet and the graduation ceremony, in a mixed atmosphere of hydrogen and nitrogen carried out will be formed.

The reason for accelerating the nitriding reaction with decreasing the S content can be explained as follows. Since S is an element that is easily concentrated at the surface and grain boundaries, S was concentrated on the surface of the steel in the S-content region of more than 10 ppm, thereby suppressing nitrogen absorption on the surface of the sheet during annealing of the hot-rolled sheet and finish annealing. In the S-content region of 10 ppm or less, on the other hand, the nitrogen absorption-suppressing effect in the S-content region of 10 ppm or less was reduced to form nitride layers.

The Researchers hypothesized that the nitride layer contained in the material, containing a trace amount of S, is clearly formed, could prevent crystal grains on the surface of the sheet, whereby a decrease in iron loss is suppressed. Based on this concept, the researchers had the idea that the iron loss of the material containing a trace amount of S continues could be reduced if elements could be added, the capable are to suppress nitrogen absorption and ability of the material containing a trace amount of S does not disturb grains to develop well. On the basis of this concept presented The researchers found in intensive studies that a trace amount of Sb is effective.

A sample prepared by adding Sb at a concentration of 40 ppm to the above sample identified by the symbol was tested under the same conditions. The results are indicated by a symbol o in 36 shown. In the following, the iron loss reducing effect of Sb will be described. While the iron loss value decreases by only 0.02 to 0.04 W / kg by adding Sb in the S-content region of more than 10 ppm, the value was changed to 10 ppm or less by adding Sb in the S-content region about 0.2 to 0.3 W / kg, which shows a marked effect of reducing the iron loss of Sb when the S content is low. No nitride layers were observed in this sample, regardless of the S content, probably due to the concentrated Sb on the surface layer of the sheet during annealing of the hot-rolled sheet and final annealing to suppress nitrogen absorption.

The Results have suggested that segregation of Sb occurs before the Onset of nitriding reaction at the surface of the Sheet metal is necessary to form a nitride in the material, the contains a trace amount of S, to suppress.

Considering the heating process, when a surface segregation of Sb competes with the nitriding reaction, the researchers studied the relationship between the heating rate during annealing of the hot rolled sheet and the iron loss. A test sample of a steel having the composition 0.0026% C, 1.62% Si, 0.20% Mn, 0.010% P, 0.30% Al, 0.0004% S, 0.0020% N and 0.004% Sb was melted in a vacuum in the laboratory. The obtained plate was washed with an acid solution after hot rolling, and the hot rolled plate was subjected to tempering. The conditions of annealing the hot rolled sheet were 75% H ₂ -25% N ₂ and an equilibrium annealing temperature of 800 ° C for 3 hours at a varying heating rate of 1 to 50 ° C / sec. The sheet was then cold rolled to a thickness of 0.5 mm and subjected to finish annealing in an atmosphere of 10% H ₂ -90% N ₂ .

37 Fig. 14 shows the relationship between the heating rate during annealing of the thus obtained hot-rolled sheet and the iron loss W _15/40 . It can be understood that the iron loss increased in the region of the heating rate exceeding 40 ° C / sec. A consideration of the texture of these materials showed that nitrides were formed on the surface layer of the steel in the sample which had been heated at a heating rate of over 40 ° C / sec, regardless of the addition of Sb. This was probably because the nitride-suppressing effect could not be well exhibited and the nitrides were formed because the sheet was exposed to a high-temperature nitriding atmosphere prior to segregation of Sb on the steel surface when the heating rate is high. From these factors, the heating rate for tempering the hot-rolled sheet is set to be 40 ° C / sec or less, taking 10 ° C / sec as the iron loss.

To investigate the optimum amount of addition for Sb, a steel having the composition 0.0026% C, 1.60% Si, 0.20% Mn, 0.020% P, 0.30% Al, 0.0004% S, 0 , 0020% N with a varying amount of Sb from trace amounts to 600 ppm in a laboratory vacuum. The obtained plate was washed with an acid solution after being hot-rolled, and the hot-rolled plate was subjected to tempering. The conditions of annealing the hot rolled sheet were an annealing atmosphere of 75% H ₂ -25% N ₂ , a heating rate of 1 ° C / sec, and a tempering annealing temperature of 800 ° C for 3 hours. The sheet was then cold rolled to a thickness of 0.5 mm and subjected to finish annealing in an atmosphere of 10% H ₂ -90% N ₂ for 3 minutes.

38 shows the relationship between the Sb content and the iron _loss W _15/50 . Out 38 When it becomes clear that the iron loss in the region of the Sb content of 10 ppm or less is lowered, it also shows that the iron loss is increased again when the Sb content is increased to more than 50 ppm by further adding Sb.

Around the reason for this iron loss increase in the Sb content region of more than 50 To examine ppm, the texture of the material under an optical Looking at a microscope. The result showed that, although none fine grain texture on the surface layer was observed, the average crystal diameter is slightly smaller had become. Because Sb is an element that is easy on the grain boundaries segregated, although not sure, the ability to the grains to develop well, due to a grain boundary resistance effect deteriorated by Sb.

Indeed the iron loss remains compared to the iron loss of the steel, which contains no Sb, small, even if Sb is added up to 600 ppm. From these establish the Sb content is set at 10 ppm or more, with its From an economic point of view, the upper limit is 500 ppm. In In view of the iron loss, the desirable Sb content is 10 ppm or more and 50 ppm or less.

Of the the iron loss reducing effect described above was also observed when 20 ppm or more Sn, an element of the Surface segregation type like Sb, were added. The iron loss was increased slightly, though 100 ppm or more Sn were added. As a result, the Sn content becomes 20 ppm or more, the upper limit being derived from economic The point of view is 1000 ppm. In terms of iron loss is the Sn content is 20 ppm or more and 100 ppm or less.

If Sb and Sn were added simultaneously, iron loss increased a combined amount of (Sb + Sn / 2) of 10 ppm or more, with a small increase in iron loss in a combined Amount of (Sb + Sn / 2) of 50 ppm or more was observed. consequently the (Sb + Sn / 2) content becomes 10 ppm or more at the same time Addition of Sb and Sn set, with its ceiling under economic Is 500 ppm or less. Considering Of iron loss, the content is desirably 10 ppm or more and 50 ppm or less.

(The reason why the Contents of other elements are limited)

Of the Reason why the contents of other components are limited should be described below.

C: Since C involves the problem of magnetic aging, it will be Content limited to 0.005% or less.

Si: Since Si is an effective element for increasing the self-resistance of the When sheet is 1.0% or more Si is added. The upper limit of the Si content is limited to 4.0%, as the magnetic flux density with the decrease in saturation the magnetic flux density is lowered when its content exceeds 4.0%.

Mn: More than 0.05% Mn was needed around the red brittleness while of hot rolling to prevent. However, since the magnetic flux density in the Mn content is reduced by 1.0% or more, its range is up 0.05 to 1.0% limited.

P: Although P is an element that improves the punching applicability sheet is essential, its content was 0.2% or less limited because an addition exceeding 0.2% makes the sheet brittle.

N: Because a lot of AlN precipitated if the N content is large, which reduces the iron loss, its range becomes 0.005% or less limited.

al: Although Al and Si are an effective element for enhancing the Is inherent resistance, the upper limit of the Al content has been increased to 1.0% limited because the magnetic flux density decreases with a decrease in saturation the magnetic flux density when its content exceeds 1.0%, decreases. The lower limit is set at 0.1% because AlN grains increase be finer than that the grains well developed, when the Al content is less than 0.1%.

(Production method)

In of the present invention conventional Method for producing the electromagnetic sheet applied provided that the S, Sb and Sn contents are as well the levels of other prescribed components in a given Range and the heating rate when starting the hot rolled Sheet is within the scope of the present invention. The melted Steel that has been refined in a converter becomes the setting degassed to a prescribed composition, then one to water and hot rolling subjected.

The Termination tempering temperature and tempering annealing temperature hot rolling are not necessarily prescribed, but may be in a normal Temperature range for producing a conventional electromagnetic Be sheet metal. The hot rolled Sheet metal is subsequently with an acid solution and hot rolled. For tempering or annealing can use either a batch furnace or a continuous annealing furnace provided that the heating rate of tempering the hot rolled Sheet is within the scope of the present invention. After molding the hot rolled Sheet to a prescribed thickness by a cold rolling process or two or more cold rolling operations with an intervening annealing, the sheet undergoes a final tempering subjected.

example

A steel shown in Table 21 was used, and the molten steel, which had been refined in a converter and degassed to set it to a prescribed composition, was then subjected to casting and hot rolling. After heating the plate for 1 hour at 1140 ° C, the sheet was hot rolled to a sheet thickness of 2.3 mm. The temperature of finish annealing of the hot rolled sheet at 800 ° C and the coiling temperature was 610 ° C. After the equalizing annealing, the hot-rolled sheet was washed with an acid solution and tempered under the conditions shown in Table 21. The annealed sheet was then cold rolled to a thickness of 0.5 mm, followed by finish annealing under the conditions shown in Table 21. The atmosphere of annealing the hot rolled sheet and the atmosphere of finish annealing were 75% H ₂ -25% N ₂ and 75% H ₂ -25% N _2, respectively. The magnetic properties were measured using a 25 cm Epstein test piece. The magnetic characteristics are also listed in Table 21.

As from Sheet Nos. 1 to 13 of the present invention in Table 21 becomes clear, a sheet with very low iron loss after completion tempering and high magnetic flux density obtained by the prescribed sheet metal components, including S, Sb and Sn, as well as the contents of the other prescribed components, be controlled to the contents of the present invention and by the heating rates during the tempering of the hot rolled Sheet is adjusted to the scope of the present invention.

The iron _{loss values} W _15/50 in the sheets Nos. 14 and 15 are high because the contents of S and (Sb + Sn / 2) in the former and the content of (Sb + Sn / 2) in the latter are outside of the scope of the present invention.

Since the heating rate of the sheets No. 16 and No. 17 is higher than the range of the present invention, the iron _loss W _{15/50 is} higher than the value of the steel of the present invention.

The iron _loss W _15/50 in the sheet No. 18 is high because the C content exceeds the range of the present invention.

Although the iron _loss W _{15/50 is} low, in the plate No. 19, the magnetic flux density B _{50 is} low because the Si content is over the range of the present invention.

Since the Mn content in the sheet No. 20 is lower than the range of the present invention, the iron _loss W _{15/50 is} high.

Although the iron _loss W _{15/50 is} low, in the plate No. 20, the magnetic flux density B _{50 is} also low because the Mn content is over the range of the present invention.

The N content is higher than the range of the present invention in the sheet No. 22, so that the iron _loss W _{15/50 is} high.

The iron _loss W _15/50 is high in the sheet No. 23 because the Al content is lower than the range of the present invention.

Although the iron _loss W _15/50 in the sheet No. 24 is low, the magnetic flux density B _{50 is also} low because the Al content exceeds the range of the present invention.

Embodiment 11

Of the crucial point of this embodiment The present invention is to reduce the iron loss of a non-oriented electromagnetic sheet, wherein the material contains a trace amount of S of 10 ppm or less by 0.03 to 0.15% P or 0.001 to 0.05% (Sb + Sn / 2) be and by the atmosphere of cranking during the annealing of the hot rolled Sheet metal and the soaking time or compensation annealing time are controlled become.

The The above problem can be solved by a method of preparation a non-oriented electromagnetic sheet to be solved characterized in that it comprises the following steps: hot rolling a plate containing in% by weight 0.005% or less C, 1.5 to 3.5% Si, 0.05 to 1.0% Mn, 0.005% or less (including zero) N, 0.1 to 1.0% Al, 0.001 or less (including zero) at S and 0.03 to 0.15% P with a balance of Fe and inevitable Contains impurities; Shapes to a given sheet thickness by one-time cold rolling or twice or more cold rolling by intervening an intermediate glow after washing with an acid solution and Tempering the hot rolled sheet in an atmosphere which contains 60% or more, for a soaking time of 1 to 6 hours; and submission of the tempered sheet a completion tempering.

The above problem can also be solved by a method of producing a non-oriented electromagnetic sheet characterized by comprising the steps of: hot-rolling a sheet in wt% of 0.005% or less C, 1, 5 to 3.5% Si, 0.05 to 1.0% Mn, 0.005% or less (inclusive of zero) N, 0.1 to 1.0% Al, 0.001% or less (inclusive of zero) of S, 0.003 to 0.15% P and 0.001 to 0.05% (Sb + Sn / 2) containing a substantial amount of Fe and unavoidable impurities; Forming at a given sheet thickness by a cold rolling operation or two or more cold rolling operations with intermediate annealing after washing with an acid solution and tempering the hot rolled sheet in an atmosphere containing 60% or more of H ₂ for an equalizing annealing time of 1 to 6 hours; and subjecting the tempered sheet to completion tempering.

In The following descriptions refer to "%" and "ppm" indicating the composition of the steel, to "% by weight" or "ppm by weight".

(Process of the invention and the reason why the S content and the conditions of tempering be limited)

The Researchers of the present invention conducted detailed studies of the Factors that reduce iron loss in the Inhibiting material containing a trace amount of S of 10 ppm or less. The results clearly showed that identifiable nitride layers on the surface of the sheet were found with decrease of the S-content and that these Nitride layers inhibited a reduction in iron loss.

Accordingly The researchers found through the collective investigations on procedures to further reduce iron loss, that of iron loss in the material containing a trace amount of S are greatly reduced could, in the 0.03 to 0.15% P or (Sb + Sn / 2) in a range of 0.001 to 0.05% were left and in which the atmosphere of exhausting and the soaking time of the hot rolled Sheet metal to be controlled.

The The present invention will now be described in more detail with reference to the experimental Results described.

• (1) C: 0,0025%, Si: 1,85%, Mn: 0,20%, P: 0,040%, Al: 0,31%, N: 0,018%
• (2) C: 0,0025%, Si: 1,85%, Mn: 0,20%, P: 0,010%, Al: 0,31%, N: 0,0018%, Sn: 0,0050%
• (3) C: 0,0025%, Si: 1,85%, Mn: 0,20%, P: 0,010%, Al: 0,31%, N: 0,0018%, Sb: 0,0040%

In order to investigate the effect of S on iron loss, steels having the following three composition systems containing varying amounts of S of a trace amount of 15 ppm were first melted in the laboratory, followed by washing with an acid solution. The obtained hot-rolled sheet was subjected to annealing under three types of combination of tempering and soaking, namely 75% H _2/3 hours soaking, 50% H _2/3 hours soaking and 75% H ₂ / 0.5 hours equalizing annealing at a tempering or annealing temperature of 800 ° C. The tempered sheet was then cold rolled to a thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ 90% N ₂ for 2 minutes.

• (1) C: 0.0025%, Si: 1.85%, Mn: 0.20%, P: 0.040%, Al: 0.31%, N: 0.018%
• (2) C: 0.0025%, Si: 1.85%, Mn: 0.20%, P: 0.010%, Al: 0.31%, N: 0.0018%, Sn: 0.0050%
• (3) C: 0.0025%, Si: 1.85%, Mn: 0.20%, P: 0.010%, Al: 0.31%, N: 0.0018%, Sb: 0.0040%

The relationship between the S content of the sample thus obtained and the iron _loss W _15/50 is in 39 shown. Out 39 it becomes clear that the iron loss is greatly reduced when the S content is 10 ppm or less. The reason is that the grains are well developed by reducing the S content. Accordingly, the S content is set to 10 ppm or less, desirably 5 ppm or less.

However, it has been found that the degree of reduction of iron loss differs depending on the combination atmosphere of tempering and "soaking" time. How out 39 becomes clear, the iron loss in the combination of 75% H _2/3 hours soaking is much lower than in the combinations 50% H _2/3 hours soaking and 75% H ₂ / 0.5 hours soaking.

For the purpose of examining the above reasons, the investigators considered the texture of the material under an optical microscope, finding distinct nitride layers on the surface layer of the sheet in all three component systems when the combinations were 50% H _2/3 hours soaking and 75% H ₂ / 0.5 hours were soaking. In the case of 75% H _2/3 hours soaking, on the other hand, nitride layers were rarely found. The nitride layer was likely to be formed during annealing of the hot rolled sheet made in a nitriding atmosphere.

Of the Reason why various nitride formation reactions were effected can be explained as follows become. Since S is an element that is easy on the surface and is concentrated at grain boundaries, suppressed concentrated S at the surface of the sheet a nitrogen absorption during annealing of the hot rolled Sheet in the S-content region of more than 10 ppm. The suppressive effect for the On the other hand, nitrogen absorption in the S-content region became 10 ppm or less deteriorated. Although an attempt was made to worsen this suppression effect by controlling the levels of P or Sn or the combination of Sb content and the atmosphere the annealing of the hot rolled Sheet metal (atmosphere of the occasion - time of equalizing annealing) There was a combination of atmosphere and tempering - soaking time in the ability to make up for it for suppression nitrogen absorption. It was assumed that these results affect the iron loss level.

• (4) C: 0,0020%, Si: 1,87%, Mn: 0,20%, P: 0,040%, Al: 0,30%, S: 0,0003%, N: 0,0017%
• (5) C: 0,0020%, Si: 1,87%, Mn: =,20%, P: 0,010%, Al: 0,30%, S: 0,0003%, N: 0,0017%, Sn: 0,0050%
• (6) C: 0,0020%, Si: 1,87%, Mn: 0,20%, P: 0,010%, Al: 0,30%, S: 0,0003%, N: 0,0017%, Sb: 0,0040%

In order to study the optimum combinations of the atmosphere of annealing and soaking time, the following composition systems were melted in the laboratory, followed by washing with an acid solution. The obtained hot-rolled sheet was tempered by changing the annealing temperature of 800 ° C. The tempered sheet was then cold rolled to a thickness of 0.5 mm, followed by finish annealing in an atmosphere of 10% H ₂ -90% N ₂ for 2 minutes.

• (4) C: 0.0020%, Si: 1.87%, Mn: 0.20%, P: 0.040%, Al: 0.30%, S: 0.0003%, N: 0.0017%
• (5) C: 0.0020%, Si: 1.87%, Mn: =, 20%, P: 0.010%, Al: 0.30%, S: 0.0003%, N: 0.0017%, Sn: 0.0050%
• (6) C: 0.0020%, Si: 1.87%, Mn: 0.20%, P: 0.010%, Al: 0.30%, S: 0.0003%, N: 0.0017%, Sb: 0.0040%

40 Fig. 14 shows the relationship between each soaking time of the hot-rolled sheet at each H ₂ concentration and the iron loss W _{15/50 of} the samples thus obtained.

Out 40 it can be seen that the iron loss in the region where the H ₂ concentration is 60% or more and the soaking time during annealing of the hot rolled sheet is 1 to 6 hours is decreased in any of the composition systems, whereby a iron _{loss value} W _15/50 of 2.5 W / kg is achieved.

(The reason why the Contents of the other components are limited)

Of the Reason why the contents of other components are limited should be described below.

C: Since C involves a magnetic aging problem, it will be Salary limited to 0.005% or less.

N: Because a lot of AlN precipitated when the N content is high, which reduces the iron loss, its range becomes 0.005% or less limited.

Si: Since Si is an effective element for increasing the self-resistance of the sheet, its lower limit is set at 1.5%. The upper limit of the Si content is set to 3.5%, since the magnetic Flux density decreases with a decrease in the saturation of the magnetic flux density when its content exceeds 3.5%.

Mn: It takes more than 0.05% Mn, around a red brittleness while of hot rolling to prevent. However, since the magnetic flux density in the Mn content is reduced by 1.0% or more, its range is up 0.05 to 1.0% limited.

al: Although Al like Si one to raise the self-resistance is effective element, was the upper limit limited to 1.0% of the Al content, since the magnetic flux density with a decrease in saturation the magnetic flux density decreases when its content exceeds 1.0%. The lower limit is set at 1.0% because AlN grains increase be fine, than that the grains could develop well, when the Al content is less than 0.1%.

P: The P content is set at 0.03% or more to the nitrogen absorption while the annealing of the hot rolled Sheet metal and while to suppress the conclusion of the event and in view of the Problem of compatibility with the hot rolling the upper limit is set at 0.15%. If, however, 0.001% or more (Sb + Sn / 2) is included, the lower limit is not defined while the upper limit is 0.15%, taking into account the compatibility with the Cold rolling, since Sb and Sn have a nitrogen absorption during the Tempering the hot rolled Suppress sheet metal and graduation tempering.

sb + Sn / 2: while Sb and Sn alike for effective suppression of nitride formation, Sb is twice as potent as Sn. Therefore their content is prescribed by (Sb + Sn / 2). Although a salary of (Sb + Sn / 2) of 0.001% or more is advantageous for nitride formation while the annealing of the hot rolled Suppressing sheet metal and graduation tempering becomes its upper limit economically limited to 500 ppm. sb or Sn is included so that (Sb + Sn / 2) within the described above remains.

(Production method)

In of the present invention conventional Method for producing the electromagnetic sheet applied provided the content of S and prescribed components except, the conditions of tempering the hot rolled Sheet metal, are in a given area. The molten steel, which purified in a converter was, is degassed, to a prescribed composition adjust, then he will be a pour and hot rolling subjected. The temperature of the final annealing and the coiling temperature of the equalizing annealing are not necessarily prescribed, but may be in a normal temperature range for producing a conventional electromagnetic sheet lie. The hot-rolled sheet is then with a Washed acid solution and hot rolled. After molding the hot rolled Sheet to a prescribed thickness by a cold rolling process or by two or more cold rolling operations with an intermediate one Tempering or annealing the steel sheet is subjected to a final tempering.

example

It The steel shown in Table 22 was used, and the molten one Steel, which had been refined in a converter, was degassed, to adjust it to a prescribed composition, was subsequently he's a pour and hot rolling subjected. After heating the plate for 1 hour at 1600 ° C, the Sheet metal hot rolled to a sheet thickness of 2.0 mm. The temperature of the Finish annealing of the hot rolled Sheet metal was 800 ° C and the "coiling" temperature was 610 ° C, followed from a tempering of the hot rolled Sheet under the conditions listed in Table 22. The tempered Sheet was then cold rolled to a thickness of 0.5 mm, followed from finish tempering under the conditions shown in Table 22. The magnetic properties were measured using a 25 cm Epstein test piece measured. The magnetic characteristic of each sheet is also in Table 2 is shown. The "soaking" time is going through the "occasion" time of the hot rolled Sheet is given in Table 22.

In Table 22, the sheets No. 1 to No. 17 have a Si concentration in of the order of magnitude by 1.8% while Sheet Nos. 18 to No. 25 have an Si concentration of the order of magnitude of 2.5%. If the sheets with the same concentration of Si content compared with each other, the steels of the present invention lower iron loss values.

These Facts show that a non-oriented electromagnetic sheet could be obtained with very low magnetic loss, even if the S content, the added amount of one of P, Sn or Sb, the atmosphere the annealing of the hot rolled Sheet metal and the "soaking" time in the area of the present invention.

On the other hand, the sheets Nos. 8 and 21 have a high W _15/50 because the S content is out of the range of the present invention.

Since the H ₂ concentration during annealing of the hot rolled sheet in the sheets Nos. 14 and 22, the soaking time during annealing of the hot rolled sheet in the sheet Nos. 15, No. 16, No. 23 and No. 24 are outside the scope of the present invention, the iron _loss W _15/50 becomes high.

The sheet No. 10 not only has a high iron _loss W _15/50 , but also involves the problem of magnetic aging since the C content exceeds the range of the present invention.

Although the iron _loss W _15/50 in the sheet No. 11 is low, the magnetic flux density B _{50 is also} low because the Mn content exceeds the range of the present invention.

The sheet No. 12 has an Al content lower than the range of the present invention, so that the iron _loss W _{15/50 is} high.

The iron _loss W _15/50 is high in Sheet # 13 because the N content is over the range of the present invention.

Since all the contents for P, Sn and Sb are out of the range of the invention in the sheet No. 17 and No. 25, the iron _loss W _{15/50 is} high.

The sheet No. 26 has an Si content over the range of the present invention, so that the magnetic flux density 850 is low despite the high iron _loss W _15/50 .

Of the P-content of Sheet No. 9 was too high to become commercial Product to be formed because the sheet broke during cold rolling.

Claims (55)

Non-oriented electromagnetic sheet consisting of: 0.005 wt% or less C, 0.2 wt% or less P, 0.005 wt% or less N, 4.5 wt% or less Si, 0 , 05 to 1.5 wt% Mn, 1.5 wt% or less Al, 0.001 wt% or less S, at least one element selected from the group consisting of 0.001 to 0.05 wt% Sb, 0.002 to 0.1 wt% Sn, 0.0005 to 0.01 wt% Se and 0.0005 to 0.01 wt% Te and a balance of Fe and inevitable Impurities. Non-oriented electromagnetic sheet after Claim 1, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Sb and Sn and the content of Sb + 0.5 × Sn 0.001 to 0.05 wt .-% is. Non-oriented electromagnetic sheet after Claim 3, wherein the content of Sb + 0.5 × Sn is 0.001 to 0.005 wt% is. Non-oriented electromagnetic sheet after Claim 3, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Sb and the Sb content is 0.001 to 0.05 wt .-% is. Non-oriented electromagnetic sheet after Claim 6, wherein the Sb content is 0.001 to 0.005 wt%. Non-oriented electromagnetic sheet after Claim 6, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Sn and the Sn content is 0.002 to 0.1 wt .-% is. Non-oriented electromagnetic sheet after Claim 9, wherein the Sn content is 0.002 to 0.01% by weight. Non-oriented electromagnetic sheet after Claim 9, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Se and Te and the content is Se + Te 0.0005 to 0.01 wt .-% is. Non-oriented electromagnetic sheet after Claim 12, wherein the content of Se + Te is 0.0005 to 0.002 wt%. is. Non-oriented electromagnetic sheet after Claim 12, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Se and the Se content is 0.0005 to 0.01 wt .-% is. Non-oriented electromagnetic sheet after Claim 15, wherein the Se content is 0.0005 to 0.002 wt%. Non-oriented electromagnetic sheet after Claim 15, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 4 wt% or less, the Mn content is 0.05 to 1% by weight, said at least one element is Te and the Te content is 0.0005 to 0.01 wt .-% is. The non-oriented electromagnetic sheet according to claim 18, wherein the Te content is 0.0005 to 0.002 Wt .-% is. Non-oriented electromagnetic sheet after Claim 18, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the unavoidable impurities are 0.005 wt% or less Ti. Non-oriented electromagnetic sheet after Claim 1, wherein said at least one element is selected from the group consisting of 0.001 to 0.005 wt .-% Sb, 0.002 to 0.01 wt% Sn, 0.0005 to 0.002 wt% Se and 0.0005 to 0.002 Wt.% Te. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 1.5 to 3 wt Al content is 0.1 to 1 wt%, the content of Si + Al is 3.5% by weight or less, said at least one element is Sb + Sn, the content of Sb + 0.5 × Sn is 0.001 to 0.05 wt .-% is and the thickness of the sheet is 0.1 to 0.35 mm. Non-oriented electromagnetic sheet after Claim 23, wherein the content of Sb + 0.5 × Sn is 0.001 to 0.005 wt% is. Non-oriented electromagnetic sheet after Claim 23, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 23, wherein said non-oriented electromagnetic Sheet has a mean crystal grain diameter of 70 to 200 microns. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 1.5 to 3 wt Al content is 0.1 to 1 wt%, the content of Si + Al is 3.5% by weight or less, said at least one element is Sb, the Sb content is from 0.001 to 0.05% by weight is and the thickness of the sheet is 0.1 to 0.35 mm. Non-oriented electromagnetic sheet after Claim 27, wherein the Sb content is 0.001 to 0.005 wt%. Non-oriented electromagnetic sheet after Claim 27, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 27, wherein said non-oriented electromagnetic Sheet has a mean crystal grain diameter of 70 to 200 microns. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is 1.5 to 3 wt Al content is 0.1 to 1 wt%, the content of Si + Al is 3.5% by weight or less, said at least one element Sn is, the Sn content 0.002 to 0.1 wt .-% is and the thickness of the sheet is 0.1 to 0.35 mm. Non-oriented electromagnetic sheet after Claim 31, wherein the Sn content is 0.002 to 0.01% by weight. Non-oriented electromagnetic sheet after Claim 31, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 31, wherein said non-oriented electromagnetic Sheet has a mean crystal grain diameter of 70 to 200 microns. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is more than 3 wt% and 4.5 wt% or less, the Al content is 0.1 to 1.5 wt%, the content of Si + Al is 4.5 wt% or less, said at least one element Sb and Sn, the content of Sb + 0.5 × Sn 0.001 to 0.05 wt .-% is and the thickness of the sheet is 0.1 to 0.35 mm. The non-oriented electromagnetic sheet according to claim 35, wherein the content of Sb + 0.5 × Sn 0.001 to 0.005 wt .-% is. Non-oriented electromagnetic sheet after Claim 35, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is more than 3 wt% and 4.5 wt% or less, the Al content is 0.1 to 1.5 wt%, the content of Si + Al is 4.5 wt% or less, said at least one element is Sb, the Sb content is from 0.001 to 0.05 wt .-% is and the thickness of the sheet is from 0.1 to 0.35 mm. Non-oriented electromagnetic sheet after Claim 38, wherein the Sb content is 0.001 to 0.005 wt%. Non-oriented electromagnetic sheet after Claim 38, wherein the S content is 0.0005 wt% or less. Non-oriented electromagnetic sheet after Claim 1, wherein the Si content is more than 3 wt% and 4.5 wt% or less, the Al content is 0.1 to 1.5 wt%, the content of Si + Al is 4.5 wt% or less, said at least one element is Sn, the Sn content is 0.002 to 0.1 wt .-% is and the thickness of the sheet is 0.1 to 0.35 mm. Non-oriented electromagnetic sheet after Claim 41, wherein the Sn content is 0.002 to 0.01% by weight. Non-oriented electromagnetic sheet after Claim 41, wherein the S content is 0.0005 wt% or less. Process for producing a non-oriented electromagnetic sheet comprising the steps of: (a) manufacture a plate consisting of 0.005 wt% or less C, 0.2 wt% or less P, 0.005 wt% or less N, 4 wt% or less Si, 0.05 to 1 wt% Mn, 1.5 wt% or less Al, 0.001 wt% or less S, at least one element selected from the group consisting from 0.001 to 0.05% by weight of Sb, 0.002 to 0.1% by weight of Sn, 0.0005 to 0.01 wt% Se and 0.0005 to 0.01 wt% Te, and a remainder Fe and unavoidable impurities; (b) hot rolling the plate to form a hot-rolled sheet; (C) Cold rolling of the hot rolled Sheet to form a cold-rolled sheet and (d) Termination ("finish-annealing") of the cold-rolled Sheet. The method of claim 44, wherein said at least an item selected is from the group consisting of 0.001 to 0.05 wt .-% Sb and 0.002 to 0.1% by weight of Sn. The method of claim 44, wherein said at least an item selected is selected from the group consisting of 0.0005 to 0.01 wt .-% Se and 0.0005 to 0.01 wt .-% Te. The method of claim 44, wherein said plate from 0.005 wt% or less C, 0.2 wt% or less P, 0.005 Wt% or less N, 1 to 4 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 Wt% of Sb + 0.5 × Sn and a balance of Fe and unavoidable impurities, and wherein said completion tempering heating the sheet at a heating rate of 40 ° C / s or less included. The method of claim 47, wherein the content of Sb + 0.5 × Sn 0.001 to 0.005 wt .-% is. The method of claim 44, wherein said plate of 0.005 wt% or less C, 0.03 to 0.15 wt% P, 0.005 wt% or less N, 1 to 3.5 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 wt% at Sb + 0.5 × Sn and a balance of Fe and unavoidable impurities, and wherein said completion tempering a continuous tempering in an atmosphere with a hydrogen concentration of 10% or more over a period of 30 seconds to 5 minutes. A method according to claim 44, wherein said plate comprises 0.005 wt% or less C, 0.2 wt% or less P, 0.005 wt% or less N, less than 1.5 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less than S, 0.001 to 0.05 wt% of Sb + 0.5 x Sn and a balance of Fe and unavoidable impurities, and wherein said final annealing is continuous annealing in an atmosphere having a hydrogen concentration of 10% or less more over a period of 30 seconds to 5 minutes. The method of claim 44, further comprising the step of tempering the hot rolled sheet. The method of claim 51, wherein said plate from 0.005 wt% or less C, 0.2 wt% or less P, 0.005 Wt% or less N, 1.5 to 4 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05 Wt% of Sb + 0.5 × Sn and a balance of Fe and unavoidable impurities, and wherein the step of tempering the hot rolled sheet comprises heating the hot rolled Sheet at a heating rate of 40 ° C / s or less in a mixed the atmosphere of hydrogen and nitrogen. The method of claim 51, wherein the content of Sb + 0.5 × Sn 0.001 to 0.005 wt .-% is. The method of claim 51, wherein said plate from 0.005 wt% or less C, 0.15 wt% or less P, 0.005 Wt% or less N, 1.5 to 3.5 wt% Si, 0.05 to 1 wt% Mn, 0.1 to 1 wt% Al, 0.001 wt% or less S, 0.001 to 0.05% by weight of Sb + 0.5 × Sn and a balance of Fe and unavoidable impurities, and wherein the step of annealing the hot rolled sheet comprises heating of the hot rolled Sheet over 1 to 6 hours in an atmosphere with a hydrogen concentration of 60% or more. The method of claim 51, wherein the step of Tempering the hot rolled Sheet heating the hot rolled Sheet over 1 to 5 minutes in an atmosphere with a hydrogen concentration of 10% or more.