JP2002194513A - Silicon-chromium steel sheet superior in working deformation characteristics and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for improving working deformation characteristics represented in elongation characteristics, of a steel, particularly of a high Si steel or a high Si and high Al steel in a normal industrial process, which have not been conventionally considered very much for a Si-containing steel. SOLUTION: This steel sheet includes 2.5 mass % or more and 10 mass % or less Si, 0.01 mass % or more and 20 mass % or less Cr, and 10 mass % or less Al, reducing C and N to be 0.01 mass % or less in total and the balance iron with unavoidable impurities, and furthermore has a mean grain size of 300 μm or less and a deformed twin-crystal generation rate of 80% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon chromium steel sheet having excellent magnetic properties, and more particularly to a silicon chromium steel sheet having excellent magnetic properties in a frequency range higher than a commercial frequency and having excellent deformation characteristics, and a method for producing the same. Things.

[0002]

2. Description of the Related Art An Fe-Si alloy is known as a material having excellent soft magnetic properties, and is frequently used mainly as an electromagnetic steel sheet having a Si content of 3.5 mass% or less, mainly in various commercial frequency iron cores. However, when the operating frequency is higher than the commercial frequency, such an electromagnetic steel sheet having a Si content of 3.5 mass% or less is disadvantageous because the iron loss increases. Therefore, in order to improve the iron loss characteristics in a frequency range higher than the commercial frequency, a material having higher electric resistance is required.

[0003] That is, since there has been an increasing trend toward energy saving for the purpose of protecting and improving the global environment in recent years, an inverter system is also adopted for electric equipment for high efficiency and power saving. The number of products is increasing, and the frequency is shifting year by year to a higher frequency range for higher efficiency. Conventionally, a reactor has been used for the purpose of improving a power factor with the use of an inverter and a high frequency, but the use of a high frequency reactor for an inverter device has been increasing for the purpose of further preventing power supply pollution. Since these high-frequency reactors are used in the frequency range of 1 kHz or more, and even 10 kHz or more, if a conventional high-frequency silicon steel sheet is used, heat generation becomes large and it is difficult to use them. Therefore, special materials had to be used.

Here, in order to improve high-frequency iron loss,
It is important to increase the specific resistance of steel, and in general,
A method of increasing the Al content has been employed. However, Si and Al
When the content of is increased, the processability deteriorated, and it was difficult to manufacture by a usual method.

As a technique for improving the manufacturability, there is disclosed a technique disclosed in Japanese Patent Laid-Open Publication No.
Is rolled to a predetermined thickness, then SiCl
By performing the high-temperature heat treatment in the gas atmosphere of ₄ , the Si
There is a method of increasing the Si content by infiltration of Si. However, this method requires expensive equipment and requires a long time for immersion Si treatment. Therefore, this method is inferior in processing ability to a normal rolling method and cannot be said to be an industrially suitable technique.

As a technique for producing a high Si content steel sheet by a rolling method, for example, Japanese Patent Application Laid-Open No. Hei 3-53025 discloses that a Fe—Cr—Si alloy is quenched immediately after hot rolling under high pressure to obtain a toughness. There is disclosed a technique for improving workability by improving the workability. Furthermore, the inventors have found that the toughness of an Fe-Si alloy can be remarkably improved by adding Cr and increasing the purity of steel, and have proposed in Japanese Patent Application Laid-Open No. H11-343544.

However, what is improved by these techniques is that
This is a toughness characteristic of steel related to the ductile-brittle transition temperature.This technology lowers the ductile-brittle transition temperature, suppresses the brittle fracture of steel, and makes the steel more ductile. However, this does not necessarily mean that the amount of deformation in the plastic deformation region is increased.

[0008] Here, the workability of steel is related to the above two problems of the ductility-brittle transition temperature and the work deformation characteristic capability. In the former case, the temperature at the time of working falls within the brittle temperature range. If so, deformation becomes difficult during steel processing. Therefore, to avoid this, it is necessary to increase the processing temperature to the ductile region.

[0009] On the other hand, the latter problem of the deformation property is a problem that occurs in the ductile temperature range, and is caused by the low deformation property. That is, there is a problem of the degree of deformation represented by elongation characteristics. Thus, "the steel is ductile" and "shows good ductility characteristics" are not necessarily the same. In fact, in difficult-to-process component systems represented by high Si steels, in the steel processing process, even if the rolling temperature is increased and the processing is performed in the ductile temperature range, the processing deformation is difficult. , A major obstacle to industrial production.

Furthermore, in the above-mentioned rolling method, the hot rolling under high pressure and the subsequent quenching technique are far from the industrial-scale rolling process, so that they are inferior in productivity and cost. Was.

Further, S, C, and impurity components in Fe
By reducing O and N to about 1 ppm each,
It is known that the processing deformation characteristics (elongation) of steel significantly improve (for example, Kenji Yasuhiko: Nikkei Science January 1993)
"Iron reborn" on page 20 of the monthly issue). However, this technology requires enormous costs for high purification,
It is not industrially feasible for mass production.

[0012]

SUMMARY OF THE INVENTION Therefore, the present invention
Conventionally, work deformation characteristics of steel, represented by elongation characteristics that were not considered much in Si-containing steel, especially high Si or high
It is an object of the present invention to propose a method of realizing improvement of working deformation characteristics in a Si and high Al component system by a normal industrial process.

[0013]

Means for Solving the Problems The inventors of the present invention conducted further detailed research to solve the above-mentioned problems, and found that the purity of steel and the Cr in steel improved the working deformation characteristics of steel. It was also found that Cr acts on the microstructure during deformation to improve the deformation characteristics. further,
The present inventors have found that it is useful to quantitatively understand the deformation twins observed in the structure of a steel sheet and to control the occurrence thereof in order to enhance the working deformation characteristics of steel, and have completed the present invention. Was. That is, the gist configuration of the present invention includes the following (1) to
As shown in (5).

(1) Si: 2.5 mass% or more and 10 mass% or less, C
r: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, C and N are reduced to a total amount of 0.01 mass% or less, the balance consists of iron and unavoidable impurities, and the average crystal grain size is 300 mass%. A silicon chromium steel sheet having excellent deformation characteristics, characterized in that it has a deformation twinning rate of 80 μm or less and μm or less.

Here, the deformation twin is a deformation structure characteristically appearing in the work structure of some metals, and its generation rate is determined by rolling the steel sheet after recrystallization at a rolling reduction of 5%. Do
It refers to a value obtained by determining the ratio of crystal grains in which twins have occurred in all the crystal grains.

(2) Si: 2.5 mass% to 10 mass%, C
r: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass% Cr] ≦ 3.0 ×
([mass% Si] + [mass% Al]), C and N are reduced to 0.01 mass% or less in total, the balance is composed of iron and unavoidable impurities, and the average crystal grain size is 300%. A silicon chromium steel sheet having excellent deformation characteristics, characterized in that it has a deformation twinning rate of 80 μm or less and μm or less.

(3) In the above (1) or (2), further selected from Mn, P, Cu, Ni, Co, Sb and Sn.
The total amount of the species or two or more elements with Si and Al is 0.
A silicon chromium steel sheet having excellent work deformation characteristics, characterized in that it is contained in a range of 01 to 15 mass%.

(4) Si: 2.5 mass% or more and 10 mass% or less, C
When hot rolling and cold rolling are performed on a steel slab containing r: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less,
A method for producing a silicon chromium steel sheet having excellent working deformation characteristics, wherein recrystallization annealing is performed after hot rolling and before cold rolling to reduce the average crystal grain size to 150 μm or less.

(5) Si: 2.5 mass% or more and 10 mass% or less, C
r: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass% Cr] ≦ 3.0 ×
([mass% Si] + [mass% Al]), and when hot rolling and cold rolling are performed on steel slabs containing C and N reduced to 0.01 mass% or less in total, A method for producing a silicon chromium steel sheet having excellent work deformation characteristics, wherein recrystallization annealing is performed after cold rolling and before cold rolling to reduce the average crystal grain size to 150 μm or less.

(6) In the above (4) or (5), the steel slab further comprises one or more elements selected from Mn, P, Cu, Ni, Co, Sb and Sn, A method for producing a silicon chromium steel sheet having excellent working deformation characteristics, characterized in that the total content of Si and Al is contained within a range of 0.01 to 15 mass%.

(7) Si: 2.5 mass% or more and 10 mass% or less, C
r: The thickness of recrystallized grains in the surface layer of the hot-rolled sheet after hot rolling when hot rolling and cold rolling are performed on steel slabs containing 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less. A method for producing a silicon chromium steel sheet having excellent working deformation characteristics, characterized in that the thickness in the direction is controlled to 3% or more of the sheet thickness from the surface of the hot-rolled sheet.

(8) Si: 2.5 mass% or more and 10 mass% or less, C
r: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass% Cr] ≦ 3.0 ×
([mass% Si] + [mass% Al]), and when hot rolling and cold rolling are performed on steel slabs containing C and N reduced to 0.01 mass% or less in total, Chromium steel sheet with excellent deformation characteristics, characterized in that the thickness of recrystallized grains in the surface layer of hot-rolled sheet after hot rolling is controlled to 3% or more of the sheet thickness from the hot-rolled sheet surface. Manufacturing method.

(9) In the above (7) or (8), the steel slab further comprises one or more elements selected from Mn, P, Cu, Ni, Co, Sb and Sn, A method for producing a silicon chromium steel sheet having excellent working deformation characteristics, characterized in that the total content of Si and Al is contained within a range of 0.01 to 15 mass%.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, experimental results that led to the discovery of the present invention will be described. Experiment 1 High-purity electrolytic iron, electrolytic chromium, and metal with a purity of 99.99% or more
Using Si and carbon as raw materials, the degree of vacuum is 1 × 10 ^-2 to 1 × 10 ^-4 To
rr range, 3.5 mass% Si-Fe
System alloy and 3.5 mass% Si-2.5 mass% Cr-Fe alloy,
Each 10 kg was melted. The impurity content of the steel ingot thus obtained is as follows: C: 10 to 120 massppm (hereinafter simply referred to as ppm), P: 70 to 80 ppm, S: 10 to 20 ppm, N: 10 to 125 ppm
ppm, O: 10 to 30 ppm. Thick these ingots 60
mm, cut to 1100 ° C, and hot-rolled to a thickness of 3.5 mm
And After that, pickle and heat to 1100 ° C again, then 12
Rolled to a thickness of 0.20 mm by cold rolling at a temperature of 0 ° C,
Annealing was performed at 00 ° C. for 1 minute.

In order to examine the working deformation characteristics of these steel sheets, tensile test pieces corresponding to JIS No. 13B were taken from these steel sheets in parallel with the rolling direction, and their elongations were measured. This measurement result is shown in FIG. 1 by dividing it into Cr-containing steel and Cr-free steel.

As shown in FIG. 1, when the total content of impurities of C and N is reduced, the ductility tends to be slightly improved. In the case of steel containing Cr in the steel, the total of C and N is particularly high. When the impurity content is in the range of 100 to 50 ppm, a peculiar phenomenon that the elongation is rapidly improved was recognized. This specific phenomenon is peculiar to the Cr-containing steel, and was not recognized at all in the steel not containing Cr. It should be noted that it is easy to control the total impurity content of C and N to 100 ppm or less even in a technology based on current industrial mass production, and from this point, this new finding is extremely useful. Things.

Experiment 2 In order to suppress the content of impurities of C and N, a steel ingot containing Cr was melted in the same manner as in Experiment 1 under the conditions of high-purity raw material and high vacuum. The impurity content of the steel ingot thus obtained is:
C: 10 to 20 ppm, P: 70 to 80 ppm, S: 10 to 20 ppm,
N: 10 to 25 ppm, O: 10 to 30 ppm. These ingots were treated under the same conditions as in Experiment 1 to obtain a 0.20 mm thick steel sheet, and then annealed at 1050 ° C. for 1 minute. Next, in order to examine the ductility characteristics of the obtained steel sheets, a tensile test piece corresponding to JIS No. 13B was sampled from these steel sheets in parallel with the rolling direction, and the elongation was measured.

From this measurement result, it was found that this material contained 2.5% Cr.
In spite of the fact that the content of C + N was less than 50 ppm by mass and that the content of C + N as an impurity was less than 50 ppm, it was found that there were many inferior elongation characteristics.

Then, in order to investigate the cause of the poor elongation characteristics, the microstructure of the steel was examined. As shown in FIG. 2, first, as shown in FIG. It turned out that there was something extremely inferior. Further, when a deformation twinning generation test described later was performed on these steel sheets, as shown in FIG. 2, the steel sheets with extremely low elongation had a deformation twinning generation rate of more than 80%. I understand.

Next, when the relationship between the occurrence of deformation twins and elongation was examined for samples having an average crystal grain size of 300 μm or less, as shown in FIG. If it exceeds, it was found that the elongation suddenly decreased and the deformation capability deteriorated.

Incidentally, the above-mentioned test for generating deformation twins is as follows.
A 5% deformation is applied to the steel by cold rolling, and a cross section cut in the thickness direction along the rolling direction after the rolling (referred to as L cross section) is polished, then corroded by a nital etch, and is magnified by 20 times. The structure is observed with a microscope, and the crystal grains (number: N1) in which deformation twinning has occurred and the crystal grains (number: N2) in which no deformation twinning has occurred are measured. At this time, the crystal grains to be measured are always adjacent and continuous, and the total number of measurements is at least 300 or more. Then, using the above measurement results, the incidence of deformation twins was calculated according to the following equation. (Deformation twin generation rate) = N1Ｎ (N1 + N2) × 100
(%)

The ductile deformation of steel is generally caused by dislocation motion. Therefore, if the dislocation movement is hindered for some reason, the ductile deformation ability is reduced. Here, deformation twins are one of the deformation structures that occur when plastic deformation due to dislocation motion is unlikely to occur, and there are reports of the occurrence of deformation twins even in Si steel or pure iron. The phenomenon that the elongation rapidly deteriorated in steel sheets with a twin generation rate of 80% or more can be confirmed as one of the causes of the decrease in ductility.

Incidentally, in Experiment 1, the difference in the occurrence of deformation twins depending on the presence or absence of Cr was measured for a steel sheet having a C + N content of 100 ppm or less. On the other hand, Cr-free steel averaged 75%
Showed a high incidence. Thus, the phenomenon that the generation of deformation twins is suppressed by containing Cr is a completely new finding. From these facts, it is considered that Cr has some positive effect on dislocation motion in steel.

Therefore, dislocations of these steel sheets were observed using a thin film transmission electron microscope (TEM). as a result,
In the case of the Si-added steel containing no Cr, dislocations were hard to move and accumulated. In the case of the Cr-containing steel, a state in which the accumulation of dislocations was relaxed and subgrains were formed was observed and confirmed.

The present invention has been made as a result of intensive studies based on the above-mentioned novel findings, and the selection of the composition and purity of steel, and the crystal structure and deformed structure form play important roles. .

Hereinafter, the present invention will be described in detail. First,
The reason for limiting the component composition range in the steel sheet of the present invention will be described. Si: 2.5 mass% or more and 10 mass% or less Si is a component effective for significantly increasing electric resistance by a synergistic effect with Cr and reducing iron loss in a high frequency range. However, when the amount of Si is less than 2.5 mass%, even if Cr and Al are used together, a specific resistance of 60 μΩcm or more cannot be obtained without sacrificing much the magnetic flux density. In addition, the steel sheet becomes difficult to process
The content is 2.5 mass% or more, and the application of the technology of the present invention is effective. On the other hand, if it exceeds 10 mass%, the workability is significantly deteriorated, and it becomes difficult to improve the workability even if the technology of improving the workability of the present invention is applied.
10 mass% or less, preferably 7 mass% or less, more preferably 3.5 mass% or more and 7 mass% or less.

Cr: not less than 0.01 mass% and not more than 20 mass% Cr greatly improves electric resistance by a synergistic effect with Si and / or Al, reduces iron loss in a high frequency range, and further improves processing deformation characteristics. It is a basic alloy component to be contained, and for that purpose, it is necessary to contain it at 0.01 mass% or more.
On the other hand, if a large amount of Cr is contained together with Si or Si and Al, the work deformation characteristics are deteriorated.

Further, it is important that Cr satisfies 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass% Cr] in relation to Si and Al. This is because a predetermined amount of Si must be contained in order to ensure magnetic properties, but the inclusion of Si degrades work deformability. It is effective to contain Cr in order to avoid the deterioration of the work deformability, and in order to obtain the effect, it is necessary to contain at least 0.8 times the total amount of Si and Al. By the inclusion of Cr, the generation of deformation twins can be effectively suppressed. However, above
Even if the ratio to the total content of Si + Al exceeds 3.0, as shown in Example 1 described below, the effect is saturated and not only increases the cost, but also leads to solid solution strengthening.
It is advantageous that s% Cr] ≦ 3.0 × ([mass% Si] + [mass% Al]).

C and N: 0.01 mass% or less in total amount Reducing the total content of C + N to 0.01 mass% or less is one of the most important technologies of the present invention, together with the effect of containing Cr, and In addition, the working deformation characteristics of steel can be greatly improved. Further, by reducing it to 50 mass% or less, the working deformation characteristics of steel are remarkably improved.

The amount of impurities other than C and N is not particularly limited. For example, S is 20 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less, and O is 50 ppm or less, preferably 30 ppm or less, more preferably Is recommended to be regulated to 15 ppm or less, or to 120 ppm or less, preferably 50 ppm or less in total of impurities C + S + N + O.

Al: not more than 10 mass% Al can be added as needed, because it can further increase the electric resistance by further adding Al to the Fe—Cr—Si alloy. % Or less includes the case where it is not added. The addition of Al can achieve a further reduction in iron loss without impairing the spirit of the present invention. Nevertheless, if a large amount of Al is added, the cost will increase. Therefore, the addition amount is set to 10 mass% or less.

As other elements, they do not hinder the inclusion of known elements, but may further contain Mn, P, Cu, Ni, Co, S
The present invention is effective when a hardly workable element such as n or Sn is contained. In this case, one or more elements selected from these elements are contained in an amount of 0.01 mass% or more for the purpose of improving the timing characteristics, that is, controlling the crystal grain size and controlling the crystal orientation. Although it is possible to apply the technology described above, the total amount of these elements and Si and Al is 15
If it is contained in a range exceeding mass%, the workability of steel cannot be improved even with the technology of the present invention. Therefore, the content of these elements is 0.01 to 15
A range of mass% is preferred.

In the steel sheet of the present invention, a synergistic effect is exhibited by increasing the specific resistance by containing Cr together with Si. As a result, iron loss particularly in a high frequency range can be significantly reduced as compared with only Si or Al, or an alloy containing Si and Al.

Further, a material having a high specific resistance so far has a poor rolling property, and the thickness is reduced only to about 0.5 mm by a normal rolling method. It has also been said that simply reducing the thickness does not allow a sufficient reduction in iron loss due to hysteresis loss. However, as a result of the inventors' earnest research, as in the present invention, by controlling the components and purity,
The effect of the high-frequency iron loss characteristics when the thickness is reduced can be promoted.

Therefore, the non-oriented electrical steel sheet of the present invention
Because of its excellent magnetic properties in the frequency range of 1 kHz or more, it is most suitable as a reactor material for inverter air conditioners and reactors for photovoltaic power generation. And an efficient reactor product can be obtained.

Next, the structure of the steel sheet will be described in detail. [Crystal Grain Size] The crystal grain size is one of the techniques for improving the processing deformation characteristics of the present invention.
It is indispensable to regulate it to 0 μm or less. That is, when the average crystal grain size exceeds 300 μm, the elongation characteristics of the steel are extremely deteriorated, and it is not possible to obtain a steel having good workability. Therefore, the average crystal grain size is set to 300 μm or less.

[Deformation twin generation rate] When the deformation twin generation rate according to the above-described deformation twin generation occurrence test method exceeds 80%,
This results in a significant reduction in processing deformation characteristics, and makes processing for obtaining various products difficult. Therefore, the steel of the present invention restricts the occurrence of deformation twins to 80% or less.

According to the above-mentioned various regulations, it is possible to improve the ductility characteristics of steel and to enhance the work deformation characteristics. Here, in order to control the incidence of deformation twins to 80% or less,
As described above, in steel containing 2.5 mass% or more of Si, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass% Cr] is contained, and further difficult-to-process. When a chemical element is contained, it is necessary to regulate the total amount of the element, Si and Al in the range of 0.01 to 15 mass%.

Finally, regarding a powerful method for further improving the characteristics of steel having the above excellent working deformation characteristics,
It is described below. The steel of the present invention has a hot-rolled sheet structure, or a recrystallized structure subjected to annealing after hot rolling or cold rolling.In particular, when performing cold rolling and performing recrystallization annealing, By regulating the structure of the steel before cold rolling, it is possible to obtain a steel having more excellent deformation property. That is, when the steel structure before cold rolling is a recrystallized structure, as shown in Examples described later, the soaking temperature and the soaking time in annealing before cold rolling are adjusted to perform cold rolling. The average grain size of the crystal in the previous steel structure is set to 150 μm or less, or in the case of a hot-rolled structure, the hot-rolling finishing temperature and the winding temperature are adjusted to adjust the fine recrystallized grains of the surface layer. A work structure having a thickness of 3% or more of the plate thickness contributes to further enhancing the work deformation characteristics of steel.
The reason for this is not clear, but it is presumed that the structure before cold rolling affects the recrystallized structure of the roll for some reason and changes the work deformation characteristics of the steel. In addition, the said processed structure is a structure recognized by observing the cross section in the thickness direction in the direction along the rolling direction of the hot-rolled sheet.

By the way, in the present invention, for the purpose of further improving the magnetic properties, rollability, corrosion resistance, and the like,
The addition of conventionally known alloy components does not impair the effects of the present invention, and it is possible to include those components. Representative examples of those components are listed below. First, the total of one or two of Sn and Sb
By adding at 0.01 to 10 mass%, the texture is improved, and as a result, the magnetic properties are improved.

Further, Ni of 5 mass% or less is a component for improving corrosion resistance, lowers the ductility-brittle transition temperature, improves workability, and suppresses eddy current loss because crystal grains are easily made fine. It is also effective in reducing high frequency iron loss. 1
Cu of less than mass% has the same effect as Ni. Mo or W of 5 mass% or less improves corrosion resistance. La, V less than 1 mass%
, Nb, Ti or Y or Zr of 0.1 mass% or less, and B of 0.1 mass% or less have an effect of increasing toughness and improving workability. Five
Co of less than mass% improves the magnetic flux density and is effective in reducing iron loss. Sb and Sn of 0.1 mass% or less improve the texture and are effective in reducing iron loss.

In order to produce a high-workability electrical steel sheet having excellent high-frequency magnetic properties according to the present invention, the raw material must have a purity of 99.9 mass%.
It is preferable to use the above high-purity electrolytic iron, electrolytic chromium, metal Si, and metal Mn. When Al and P are added, they also use high-purity raw materials. Alternatively, in the case of manufacturing by the converter method, care must be taken to sufficiently refine to a predetermined purity and not to be contaminated in a later step. At the time of smelting, in addition to the converter method, for example, a high-vacuum (pressure of 10 ⁻³ Torr or less) vacuum melting furnace can be used.

In the subsequent hot rolling, the workability in the next step of cold rolling or warm rolling, ie, the rolling property, can be improved by rolling as thin as possible. This is based on the new finding that, in the case of the Fe-Cr-Si-based alloy composition according to the present invention, the surface portion of the hot-rolled sheet has higher toughness than the central portion and has excellent workability. is there. The thickness of the hot rolled sheet for that purpose is 3 mm or less, preferably 2.
5 mm or less, more preferably 2.0 mm or less.

Since the toughness of the hot-rolled sheet is improved, it can be further rolled warm or cold to make a thin sheet having a thickness of 0.4 mm or less. In general, it is well known that reducing the plate thickness advantageously suppresses eddy current loss, especially at high frequencies, and reduces iron loss. However, materials having high electric resistance have poor rollability so far, and the thickness has been reduced to only about 0.5 mm by a normal rolling method. It has also been said that simply reducing the thickness does not allow a sufficient reduction in iron loss due to hysteresis loss. In this regard, the present invention has found that the effect of the high-frequency iron loss characteristics when the thickness is reduced can be promoted by selecting the component system and the purity. In order to obtain such an effect of thickness reduction, it is effective to make the plate thickness 0.4 mm or less. However, it is industrially impossible to reduce the thickness to less than 0.01 mm.
mm, preferably 0.03 to 0.35 mm.

For subsequent annealing and surface finishing, the same steps as those for a normal electromagnetic steel sheet or an electromagnetic stainless steel sheet can be applied.
At that time, in particular surface finish of the surface roughness is essential to less 0.5 μmR _a are as described above. For this purpose, it is preferable to finish the surface of the steel sheet by controlling the surface roughness of the rolling rolls during cold rolling and by performing rolling repeatedly.

[0056]

EXAMPLES Example 1 Steels having various component compositions shown in Tables 1 and 2 were melted using a vacuum degassing apparatus. At this time, the time and the degree of vacuum of the rimmed decarburization treatment were changed, and the C and N contents in the steel were changed.
Further, as a result of performing the deoxidation treatment by adding Si or Al, each steel was O: 10 to 20 mass%. Further, since desulfurized hot metal was used, each steel was in the range of S: 20 to 30 mass%.

The molten steel was formed into a slab using a continuous casting machine, reheated to 1200 ° C., and then hot-rolled into a hot-rolled steel strip having a thickness of 2.5 mm. Then, subjected to hot-rolled sheet annealing at 1100 ° C. for 30 seconds, further pickling the steel sheet after hot-rolled sheet annealing,
Cold rolling was performed at a temperature of 200 ° C. to a final thickness of 0.50 mm. Then, it was degreased and annealed at 950 ° C. for 60 seconds to obtain a product.

From the product thus obtained, test specimens are taken along the rolling direction, and subjected to a twinning deformation test, an elongation test, and an average crystal grain size (the area obtained by dividing the measured area by the number is converted into a circle equivalent diameter). And the magnetic properties (W _{1 / 1k} ) were measured. The results are shown in Tables 3 and 4.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

[Table 4]

In Table 3, steel plates 1, 3 and 8 are conventional high Si steels and do not contain Cr or have insufficient Cr content for the purpose of the present invention; Further, since the incidence of deformation twins is high, it is difficult to subject these steel sheets to general processing to obtain products. Moreover, the steel plate 9 and
Sample No. 10 is inferior in elongation because the amounts of C and N are out of the range of the present invention, and the incidence of deformation twin exceeds 80%.

On the other hand, the steel plates 2, 4, 5, 6, 7 and 11
According to the present invention, Cr is contained, and the contents of N and C are reduced to 100 ppm or less, the average crystal grain size is suppressed to 300 μm or less, and the occurrence of deformation twins is suppressed to 80% or less. is there. Each of these steel sheets had greater elongation, improved work deformation characteristics, and excellent magnetic characteristics compared to conventional high Si steels. The steel sheet 11 is an example in which the value of Cr / (Si + Al) is high. The steel plates 7 and 8 have the same average crystal grain size as 20 μm, but the steel plate 7 having a crystal grain size after annealing of a hot-rolled sheet (crystal grain size before cold rolling) of 150 μm or less has a larger elongation. Excellent in processing deformation characteristics.

Example 2 A steel slab having the composition of steel type G shown in Table 1 was
After reheating to 00 ° C., a hot-rolled steel strip having a thickness of 2.2 mm was formed by hot rolling. At this time, the finish rolling temperature is raised from 1100 ° C to 80
Various changes between 0 ° C and winding temperature of 250-
Various changes were made in the range of 800 ° C. After examining the hot rolled structure of the hot-rolled steel strip, it was pickled and cold-rolled at a temperature of 200 ° C. to a final thickness of 0.5 mm. Then, it was degreased and annealed at 950-1150 ° C. for 60 seconds. A test specimen was collected from the cold-rolled sheet thus obtained, and subjected to a twinning deformation test, an elongation test, and a measurement of an average crystal grain size (an area obtained by dividing the measured area by the number was converted into a circle equivalent diameter). Table 5 shows the results.

[0066]

[Table 5]

[0067]

According to the present invention, difficult-to-work steels typified by high Si content steels, which were conventionally difficult to manufacture except using special equipment, are mass-produced by a normal rolling process. You can open your way.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the elongation of a steel sheet and the total content of C and N.

FIG. 2 is a diagram showing that the relationship between the elongation of a steel sheet and the average crystal grain size changes depending on the rate of deformation twinning.

FIG. 3 is a diagram showing the relationship between the elongation of a steel sheet and the rate of deformation twinning.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akihiro Matsuzaki 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. Chome (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Michio Komatsubara 1-chome, Mizushima Kawasaki-dori Kurashiki-shi, Okayama Prefecture (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) 4K033 CA07 CA09 CA10 JA01

Claims (9)

[Claims] (1) Si: 2.5 mass% to 10 mass%, Cr: 0.01 mass% to 20 mass% and Al: 10 mass% or less, and the total amount of C and N is reduced to 0.01 mass% or less, and the balance is reduced. Is a silicon chromium steel sheet having excellent working deformation characteristics, comprising iron and unavoidable impurities, having an average crystal grain size of 300 μm or less and a deformation twin generation rate of 80% or less. (2) Si: 2.5 mass% or more and 10 mass% or less, Cr: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass % Cr] ≤3.0 ×
([mass% Si] + [mass% Al]), C and N are reduced to 0.01 mass% or less in total, the balance is composed of iron and unavoidable impurities, and the average crystal grain size is 300%. A silicon chromium steel sheet having excellent deformation characteristics, characterized in that it has a deformation twinning rate of 80 μm or less and μm or less. 3. The method according to claim 1, wherein Mn,
One or more elements selected from P, Cu, Ni, Co, Sb and Sn are combined with Si and Al in a total amount of 0.01 to 15 ma.
Silicon chromium steel sheet with excellent processing deformation characteristics characterized by being contained below the ss% range. 4. A steel slab containing 2.5 mass% or more and 10 mass% or less of Si, 0.01 mass% or more and 20 mass% or less of Cr and 10 mass% or less of Al is subjected to hot rolling and cold rolling. A method for producing a silicon chromium steel sheet having excellent working deformation characteristics, wherein recrystallization annealing is performed after rolling and before cold rolling to reduce the average crystal grain size to 150 μm or less. (5) Si: 2.5 mass% or more and 10 mass% or less, Cr: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass % Cr] ≤3.0 ×
([mass% Si] + [mass% Al]), and when hot rolling and cold rolling are performed on steel slabs containing C and N reduced to 0.01 mass% or less in total, A method for producing a silicon chromium steel sheet having excellent work deformation characteristics, wherein recrystallization annealing is performed after cold rolling and before cold rolling to reduce the average crystal grain size to 150 μm or less. 6. The steel slab according to claim 4 or 5,
Further, one or more elements selected from Mn, P, Cu, Ni, Co, Sb and Sn are contained in a range where the total amount of Si and Al is 0.01 to 15 mass%. A method for producing a silicon chromium steel sheet having excellent deformation characteristics. 7. Hot rolling and cold rolling of a steel slab containing 2.5 mass% or more and 10 mass% or less of Si, 0.01 mass% or more and 20 mass% or less of Cr, and 10 mass% or less of Al. A silicon chromium steel sheet having excellent working deformation characteristics, characterized in that the thickness of the recrystallized grains in the surface layer of the hot-rolled sheet after rolling is controlled to 3% or more of the sheet thickness from the hot-rolled sheet surface. Production method. 8. Si: 2.5 mass% or more and 10 mass% or less, Cr: 0.01 mass% or more and 20 mass% or less and Al: 10 mass% or less, 0.8 × ([mass% Si] + [mass% Al]) ≦ [mass % Cr] ≤3.0 ×
([mass% Si] + [mass% Al]), and when hot rolling and cold rolling are performed on steel slabs containing C and N reduced to 0.01 mass% or less in total, Chromium steel sheet with excellent deformation characteristics, characterized in that the thickness of recrystallized grains in the surface layer of hot-rolled sheet after hot rolling is controlled to 3% or more of the sheet thickness from the hot-rolled sheet surface. Manufacturing method. 9. The steel slab according to claim 7, wherein:
Further, one or more elements selected from Mn, P, Cu, Ni, Co, Sb and Sn are contained in a range where the total amount of Si and Al is 0.01 to 15 mass%. A method for producing a silicon chromium steel sheet having excellent deformation characteristics.