KR20110074547A - Method for manufacturing grain-oriented electrical steel sheet - Google Patents

Abstract

When producing a grain-oriented electrical steel sheet using a slab made of a component system not containing an inhibitor, at least one selected from B, Nb, and V as a trace element in total is contained in the slab in a total amount of 10 to 150 ppm, and impurities The ratio of Al and N contained as Al / N? 1.4 is preferably, and the average temperature increase rate between 600 and 800 ° C. in recrystallization annealing is 15 ° C./s or more, thereby not containing an inhibitor. Provided is a method for producing a grain-oriented electrical steel sheet having high and stable magnetic properties using a component system.

Description

METHOD FOR MANUFACTURING GRAIN-ORIENTED ELECTRICAL STEEL SHEET}

The present invention relates to a method for producing a grain oriented electrical steel sheet suitable for use in applications such as iron core materials of transformers.

For grain-oriented electrical steel sheets, precipitates called inhibitors are used to preferentially secondary recrystallization of grains having a Goss orientation during final annealing. It is known as a general technique. For example, Patent Document 1 discloses a method of containing Al and S in specified amounts, that is, a method of using AlN and MnS as an inhibitor. In addition, Patent Document 2 discloses a method of containing a specified amount of at least one of S and Se, that is, a method of using MnS and MnSe as an inhibitor. These methods are industrially used, respectively.

In addition, for the purpose of strengthening the action of these inhibitors, Patent Document 3 includes a method using Pb, Sb, Nb, and Te, and Patent Document 4 discloses Zr, Ti, B, Nb, Ta, V, A method of using Cr and Mo is disclosed.

The method of using these inhibitors is an effective method for stably developing secondary recrystallized grains, but in order to finely disperse the inhibitors in the steel, at a high temperature of 1300 ° C or higher. It was necessary to reinvent the inhibitor-forming element once by slab reheating. In addition, since the inhibitor component causes deterioration of magnetic properties after secondary recrystallization, a purification annealing process for removing the inhibitor is required, and the process is performed at a high temperature of 1100 ° C. or higher, In addition, the atmosphere needed to be controlled.

On the other hand, in the raw material which does not contain an inhibitor component, patent document 5 proposes the technique of developing Goss oriented grain by secondary recrystallization. This method, by maximizing the exclusion of impurities, such as the inhibitor component, by presenting the misorientation dependence of the grain boundary energy of the grain boundary at the first recrystallization, thereby inhibiting the inhibitor It is a technique for secondary recrystallization of particles having a goth orientation without using. This effect is called the texture inhibition effect. Since the method of the said patent document 5 does not require the process of purifying an inhibitor, it does not need to make final finishing annealing high temperature, and since it does not need to disperse an inhibitor finely in steel, high temperature slab heating is also needed. In that case, the method has a great advantage in terms of manufacturing cost and equipment maintenance.

Japanese Patent Publication No. 40-15644 Japanese Patent Publication No. 51-13469 Japanese Patent Publication No. 38-8214 Japanese Patent Laid-Open No. 52-24116 Japanese Unexamined Patent Publication No. 2000-129356

However, since the component system which does not contain an inhibitor has few precipitates which suppress grain growth, particle size tends to become large by grain growth at the time of annealing, ie, the annealing temperature dependence was strong. For this reason, the particle size after the hot band annealing or the recrystallization annealing is also fluctuated by a slight variation of the process conditions, specifically, the variation of the respective annealing temperatures, and thus the overall width of the product coil. The magnetic properties of X are varied, and the problem that good magnetic properties are not obtained as a whole of the coil is brought to the present.

The present invention advantageously solves the above problems, and an object thereof is to propose an advantageous method for producing a grain-oriented electrical steel sheet capable of achieving high stabilization of product magnetic properties.

By the way, in order to solve the problems mentioned above, the inventors made extensive studies on elements thought to have an influence on the particle size control, and as a result, after restricting the ratio of Al and N to a predetermined range, It was found that by adding a trace amount, good and stable magnetic properties can be obtained. Hereinafter, the experiment which led to this invention is demonstrated.

In addition, unless otherwise indicated, a% display shall mean the mass%. The ppm display is also the value in mass.

(Experiment 1a)

C: 0.012-0.073%, Si: 3.15-3.33%, Mn: 0.06-0.09%, Cr: 0.02-0.06%, Sb: 0.018-0.045%, Al: 35-100 ppm, N: 14-70 ppm, S : 11-25 ppm and Nb: 20-50 ppm, The steel slab which becomes a composition of remainder Fe and an unavoidable impurity is manufactured by continuous casting process, and it is heated by hot rolling after slab heating at 1250 degreeC. A hot rolled steel sheet of 2.3 mm thickness was used. Next, after performing 15 second hot-rolled sheet annealing at 1050 degreeC, it finished by the cold rolling to the plate thickness of 0.23 mm. In addition, after recrystallization annealing having a crack condition of 60 seconds at 850 ° C, after applying an annealing separator mainly composed of MgO, finish annealing was maintained at 1200 ° C for 10 hours. Finally, flattening annealing, which also serves as the formation of a tension coating mainly composed of magnesium phosphate and boric acid, was performed at 900 ° C. for 15 seconds to produce a grain-oriented electrical steel sheet.

The magnetic flux density (B ₈ ) (magnetization force 800 A / m) of the obtained sample was measured in accordance with the method of JIS C 2550. Although the obtained magnetic flux density seemed deviated at first glance, a very good correlation was obtained by arranging by the ratio of Al and N of the steel slab component.

The result is shown in FIG.

As shown in the figure, when the Al / N (horizontal axis: mass ratio) is small, the magnetic flux density (B ₈ ) (vertical axis: unit T) tends to be lowered, and in particular, when Al / N <1.4, the deviation is also large. Can be.

(Experiment 1b)

C: 0.035 to 0.043%, Si: 3.23 to 3.30%, Mn: 0.06 to 0.09%, Sb: 0.027 to 0.045%, Cr: 0.02 to 0.06%, P: 0.012 to 0.015%, Al: 28 to 100 ppm, N : 17 to 50 ppm, S: 15 to 26 ppm and Nb: 25 to 47 ppm, the remainder being produced by continuous casting of a steel slab made of Fe and unavoidable impurities, and heated at 1250 ° C., followed by hot It was made into the hot rolled sheet of 2.3 mm thickness by rolling, and then after hot-rolled sheet annealing for 15 second at 1050 degreeC, it finished by cold rolling to the final plate thickness of 0.23 mm. Thereafter, after recrystallization annealing was performed in a humid atmosphere of 50% N ₂ -50% H _{2 at} a crack condition of 850 ° C. for 60 seconds, an annealing separator mainly containing MgO was applied, and then maintained at 1200 ° C. for 10 hours. Finish annealing was performed. Thereafter, planarization annealing serving as a tension imparting coating mainly composed of magnesium phosphate and boric acid was performed at 900 ° C. under conditions of 15 seconds.

After planarization annealing, iron loss of the entire length of the coil was measured in advance using an in-line iron loss meter, and a total of five samples including the point where the iron loss was bad in the total length measurement: three points and the coil both ends: two points were taken. The magnetic property (magnetic flux density (B ₈ )) of the obtained sample was measured by the method described in JIS C 2550, and the value having the worst magnetic property among the five points was taken as the representative value of the coil. In this method, since a representative value worsens when the deviation of a magnetic characteristic is large, it can be considered that the deviation in a coil can also be quantified.

Although the obtained magnetic properties seemed to be deviating at first glance, a good correlation was obtained by arranging by the ratio (Al / N) of Al and N in the steel slab component. The result is shown in FIG.

It can be seen from FIG. 2 that when the Al / N (horizontal axis: mass ratio) decreases, the magnetic properties (vertical axis: magnetic flux density (B ₈ (T))) deteriorate, and especially below 1.4, the deviation increases.

1 and 2, the magnetic flux density tends to be slightly higher when Al / N? 2.0.

Therefore, in order to pursue the reason why Al / N has a correlation with the magnetic flux density, further experiments were conducted. That is, in the above-described experiments 1a and 1b, since Al / N was found to have a change in magnetic flux density even near 2.0, Al and N present as impurities formed AlN (Al / N was 27/14 kPa in mass ratio). 1.93), it was speculated that the behavior of this compound may be involved. In order to further pursue this conjecture, experiments were conducted in which various nitride-forming elements were added.

(Experiment 2a)

C: 0.045 to 0.062%, Si: 3.20 to 3.31%, Mn: 0.04 to 0.16%, Cr: 0.03 to 0.11%, Sb: 0.015 to 0.037%, Mo: 0.03 to 0.05%, Al: 55 to 97 ppm, N : Steel slab containing 20 to 49 ppm (Al / N: 1.98 to 3.10) and S: 17 to 27 ppm, and containing about 50 ppm each of Zr, Ti, B, Nb and V by selecting one type. And steel slabs which did not contain all of these trace elements (Zr, Ti, B, Nb and V) were each produced by continuous casting. The balance of the composition of each steel slab was made into Fe and an unavoidable impurity. These steel slabs were heated to 1250 ° C., and then hot rolled to form a hot rolled sheet having a thickness of 2.2 mm. Subsequently, after performing hot-rolled sheet annealing for 60 second at 1100 degreeC, it finished by the cold rolling to the plate thickness of 0.23 mm. In addition, after recrystallization annealing having a crack condition of 80 seconds at 840 ° C., an annealing separator mainly composed of MgO was applied, followed by finish annealing held at 1200 ° C. for 10 hours. Finally, planarization annealing, which also serves as the formation of a tension imparting coating mainly composed of magnesium phosphate and boric acid, was performed at 900 ° C. for 15 seconds to produce a grain-oriented electrical steel sheet.

The magnetic flux density (B ₈ ) of the obtained sample was measured in accordance with the method of JIS C 2550. The result is shown in FIG.

As shown in the figure, it can be seen that the magnetic flux density B ₈ (vertical axis: unit T) obtained is largely different depending on the kind of Zr, Ti, B, Nb, and V added. That is, the sample to which Zr (left end) and Ti (second from the left) were added has low magnetic flux density, and secondary recrystallization was not expressed. On the other hand, when Nb (3rd copper), B (3rd from right), and V (2nd copper) were added, it turned out that the magnetic flux density became high compared with the case of not adding (right end). lost.

(Experiment 2b)

C: 0.045 to 0.062%, Si: 3.20 to 3.31%, Mn: 0.04 to 0.16%, Sb: 0.015 to 0.037%, Cr: 0.03 to 0.11%, Mo: 0.03 to 0.05%, Al: 55 to 97 ppm, N : Steel slab containing 20 to 49 ppm (Al / N: 1.98 to 3.10) and S: 17 to 27 ppm, and selected from Zr, Ti, Nb, B, and V and added about 50 ppm each. And steel slabs which do not contain all of these trace elements (Zr, Ti, Nb, B and V) were each produced by continuous casting. The remainder of either steel slab was Fe and inevitable impurities. After each slab was heated at 1250 ° C, the steel slab was heated to a hot rolled sheet having a thickness of 2.8 mm by hot rolling, followed by annealing for 60 seconds at 1100 ° C, and finished to a final plate thickness of 0.30 mm by cold rolling. Thereafter, after recrystallization annealing was performed at 50% N ₂ -50% H _{2 in} a wet atmosphere at a cracking condition of 840 ° C. and 80 seconds, after applying an annealing separator mainly composed of MgO, the mixture was kept at 1200 ° C. for 10 hours. Finish annealing was performed. Thereafter, planarization annealing serving as a tension imparting coating mainly composed of magnesium phosphate and boric acid was performed at 900 ° C. under conditions of 15 seconds.

After flattening annealing, the iron loss of the entire length of the coil was measured in advance using an in-line iron loss meter, and a sample of 5 points in total was taken from the coil in the same manner as in Experiment 1b, and the magnetic properties of the obtained sample were measured by the method described in JIS C 2550, The value with the worst magnetic characteristic among 5 points | pieces was made into the representative value of the coil.

The obtained result is shown in FIG.

It can be seen from FIG. 4 that the magnetic flux density B ₈ (vertical axis: unit T) differs greatly depending on the trace element added by about 50 ppm. Here, the secondary recrystallization did not express in the Zr additive (left end) and Ti additive (second from left) where the magnetic flux density was low. Moreover, when Nb (third from left side), B (third from right side), and V (third from east side) were added, it turned out that magnetic flux density becomes high compared with the case where nothing is added (right end).

As described above, the reason why the magnetic properties change by the addition of trace elements or the reason why the magnetic properties are improved by adding at least one of B, Nb and V are not necessarily elucidated. I think like this.

The thermodynamic stability of nitrides in additives (particularly trace additives) and impurities has been investigated in detail, and it has been found that the stability varies depending on the element bound to nitrogen. In the element added in the present experiments 2a and 2b, the stability of the nitride is Zr, Ti, Al, B, Nb and V in terms of stability.

According to the results of FIGS. 3 and 4, the elements having poor magnetic properties were Zr and Ti, which were more stable than Al, and the elements having good magnetic properties were B, Nb, and V, which were more unstable than Al. In this respect, if Zr or Ti is present, it is presumed that N in the steel combines with these elements to form ZrN or TiN deteriorating the magnetic properties. On the other hand, even if B, Nb or V exists, it is thought that N in steel forms stable nitride with Al, and nitride with B, Nb or V is not formed.

In Experiments 1a and 1b, when Al / N was low, the magnetic properties were low even in the presence of Nb. This reason is considered to be the reason that N stoichiometrically became excess compared with Al, and Nb couple | bonded with excess N and formed nitride.

In extreme terms, the presence of nitrides of Zr, Ti, B, Nb, or V is deteriorating the magnetic properties. It is presumed that the micro-precipitates, such as nitrides of these trace elements, increase, so that the texture-inhibition effect, which makes the grain boundary energy difference of the crystal grains of the steel sheet a driving force, weaken.

On the other hand, as mentioned above, when a trace amount of B, Nb or V was added under the conditions which do not form nitride, magnetic property became favorable compared with the case where it did not add. Although this reason is not certain, it was found by the inventors further investigation that the crystal grain size after recrystallization annealing becomes fine and uniform when at least one of B, Nb, and V is added. It was speculated that this resulted in the improvement of the magnetic properties because the texture activation effect could be exhibited to the maximum by excluding the effect of the size effect of the particle size (a phenomenon in which particles more than about twice the average particle diameter tends to cause abnormal grain growth). Doing. The particle size equalization effect contributes to the improvement of the variation of the magnetic properties in the same sample, which was a problem of the component system not containing an inhibitor.

In view of the above results and considerations, the inventors conducted further experiments in order to pursue particle size uniformity effects. As a result, the inventors found that a small amount of a specific element was added as described above, the ratio of Al and N as impurities was defined, and the rate of heating at the time of recrystallization annealing was further controlled. .

(Experiment 3)

C: 0.034%, Si: 3.30%, Mn: 0.07%, Sb: 0.030%, Sn: 0.059%, Cr: 0.05%, Al: 56 ppm, N: 29 ppm (Al / N: 1.93), S: 15 It contained ppm and Nb: 35 ppm, and the balance was produced by continuous casting of a steel slab composed of Fe and unavoidable impurities. After heating the slab at 1150 ° C, the steel slab was heated to 3.0 mm thick by hot rolling, followed by annealing for 30 seconds at 950 ° C, and then to a median thickness of 1.8 mm by cold rolling first. After the intermediate annealing for 40 seconds at 1000 ° C., the film was finished to the final plate thickness of 0.23 mm by second cold rolling. Thereafter, recrystallization annealing was performed at 50% N ₂ -50% H ₂ wet atmosphere at a crack condition of 850 ° C for 60 seconds. At this time, the average temperature increase rate between 600-800 degreeC was changed variously.

The recrystallized particle diameter of the obtained sample was measured, and the average particle diameter and its standard deviation were calculated | required from the particle size distribution. The method for measuring the recrystallized grain size is obtained by cutting a cross section perpendicular to the rolling direction of the sample, etching with a nital liquid, and then observing with an optical microscope, and elliptical approximation of particles in the field of view by an image processing apparatus. The grains were approximated to ellipses, and the average of the major and minor axis dimensions was taken as the particle size of the particles. The said sample was extract | collected from the both ends and center part in the width direction of the produced recrystallization board, and the observation point was made into the board thickness total thickness. Samples were taken so that the number of observed particles was at least 2000 or more in total in both ends and the center part.

The standard deviation (vertical axis) when the average particle diameter is normalized to 1.0 in FIG. 5 is shown by the relationship with the heating rate of recrystallization annealing (horizontal axis (average temperature rising rate between 600-800 degreeC): unit ° C / s).

As shown in the same figure, it turns out that standard deviation is small, ie, the particle size deviation is small, so that the average temperature increase rate between 600-800 degreeC is quick.

After experiments and considerations as described above, the inventors regulate the ratio of Al and N present as impurities in the grain-oriented electrical steel sheet containing no inhibitor, and further, by adding a trace amount of at least one of B, Nb and V. The conclusion is that good magnetic properties are obtained.

In addition, after further experiments and considerations, the inventors have defined a ratio of Al and N, and in a system in which at least one of B, Nb, and V is added in a small amount, the inventors further control the temperature increase rate during recrystallization annealing, thereby further improving magnetic properties. It was concluded that a grain-oriented electrical steel sheet having characteristics (including uniformity of magnetic properties) was obtained.

This invention is based on the said knowledge.

That is, the summary structure of this invention is as follows.

(1) In mass%, C: 0.10% or less, Si: 2.0 to 8.0% and Mn: 0.005 to 1.0%, Al is 100 ppm or less, and N, S and Se are each 50 ppm or less, In the method of manufacturing a grain-oriented electrical steel sheet comprising a series of steps in which a balance is finished by rolling a slab made of Fe and unavoidable impurities to a final plate thickness, followed by recrystallization annealing, and then finishing annealing,

The ratio of the amount of Al and the amount of N contained in the slab is 1.4 or more in mass ratio, and 10 to 150 ppm of one or two or more selected from B, Nb and V is further contained in the slab in total. The manufacturing method of the grain-oriented electrical steel sheet characterized by the above-mentioned.

(2) The above-mentioned step of rolling the slab to finish the final plate thickness is performed by hot rolling the slab, performing hot-rolled sheet annealing as necessary, and then performing two or more cold rollings having one or intermediate annealing therebetween. The manufacturing method of the grain-oriented electrical steel sheet as described in said (1) which is a process.

(3) In the slab, Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, P: 0.005 to 0.50%, Sn: 0.005 to 0.50%, Sb: 0.005 to 0.50% , Bi: 0.005 to 0.50% and Mo: at least one selected from 0.005 to 0.10%. The method for producing a grain-oriented electrical steel sheet according to the above (1) or (2).

(4) In mass%, C: 0.10% or less, Si: 2.0% to 8.0% and Mn: 0.005% to 1.0%, and Al is 100 ppm or less, and N, S and Se are respectively reduced to 50 ppm or less. In the method for producing a grain-oriented electrical steel sheet comprising a series of steps in which the remainder is rolled out of a slab made of Fe and unavoidable impurities to a final sheet thickness, followed by recrystallization annealing, and then finish annealing,

In addition to the slab, one or two or more selected from B, Nb, and V may be included in the range of 10 to 150 ppm in total, and the ratio of Al and N contained as impurities may be Al / N≥1.4 in mass ratio. Furthermore, the average temperature increase rate between 600-800 degreeC in recrystallization annealing shall be 15 degreeC / s or more, The manufacturing method of the grain-oriented electrical steel sheet characterized by the above-mentioned.

(5) The above-mentioned step of rolling the slab to finish the final sheet thickness is performed by hot rolling the slab, performing hot-rolled sheet annealing as necessary, and then performing cold rolling two or more times having one or intermediate annealing therebetween. The manufacturing method of the grain-oriented electrical steel sheet as described in said (4) which is a process.

(6) In addition to the mass% in the slab, Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, P: 0.005 to 0.50%, Sn: 0.005 to 0.50%, Sb: 0.005 At least 1 sort (s) chosen from -0.50%, Bi: 0.005-0.50%, and Mo: 0.005-0.100% is contained, The manufacturing method of the grain-oriented electrical steel sheet as described in said (4) or (5) characterized by the above-mentioned.

(7) The directionality according to any one of (4) to (6) above, wherein the particle size distribution of the recrystallized particles of the steel sheet after recrystallization annealing satisfies 0.3 or less when the average particle diameter is normalized to 1.0. Method of manufacturing electrical steel sheet.

According to the present invention, in a component system that does not substantially contain an inhibitor, variations in the magnetic properties in the longitudinal direction and the width direction of the coil can be reduced, and as a result, good magnetic properties (ie, high-stable stability) as the whole product coil are obtained. A grain-oriented electrical steel sheet having magnetic properties) can be obtained.

1 is of Al and N in the steel ratio (Al / N) (the horizontal axis: mass) and the magnetic flux density (B _8): a view showing the relationship between the (vertical axis unit T).
Fig. 2 is a graph showing the relationship between the ratio (Al / N) (horizontal axis: mass ratio) of the impurities Al and N in the steel and the magnetic flux density B ₈ (vertical axis: unit T).
FIG. 3 is a graph showing the relationship between the type (horizontal axis) and magnetic flux density B ₈ (vertical axis: unit T) of trace elements added to steel.
4 is a diagram showing the relationship between the type (horizontal axis) and magnetic flux density (B ₈ ) (vertical axis: unit T) of trace elements added to steel.
5 is a diagram showing the standard deviation (vertical axis) when the average particle diameter is normalized to 1.0 in relation to the heating rate (horizontal axis: ° C / s) of recrystallization annealing.

Hereinafter, the present invention will be described in detail.

First, in this invention, the reason which limited the component composition of slab to said range is demonstrated.

In addition, although the reason for limitation is described for each element as a principle, this does not mean that each element influences each other independently, but it is effective under the premise that other elements are in the scope of this specification. In other words, the range limitation of each element obtains the target effect and the more preferable effect by the range limitation of another element or the combination effect with manufacturing conditions.

As mentioned above,% and ppm in composition are mass references | standards unless there is particular notice.

C: 0.10% or less

When the amount of C exceeds 0.10%, it becomes difficult to reduce to 50 ppm or less which does not generate a magnetic aging even if decarburization process is performed. Therefore, the amount of C was limited to 0.10% or less. An especially preferable range is 0.04% or less. Although less C is preferable, it is common to contain 30 ppm or more industrially.

Si: 2.0% to 8.0%

Si is an element necessary for improving the iron loss by increasing the specific resistance of the steel, but the effect is insufficient at less than 2.0%. On the other hand, when it exceeds 8.0%, workability will deteriorate and rolling will become difficult. For this reason, Si amount was limited to 2.0 to 8.0% of range. The minimum with particular preference is 2.8%. Moreover, an especially preferable upper limit is 3.5%.

Mn: 0.005 to 1.0%

Mn is an element necessary for improving hot workability, but the effect is insufficient at less than 0.005%. On the other hand, when it exceeds 1.0%, the magnetic flux density of a product plate will fall. For this reason, Mn amount was limited to 0.005 to 1.0% of range. The minimum with particular preference is 0.02%. Moreover, an especially preferable upper limit is 0.20%.

Al: 100 ppm or less, and N, S, Se: 50 ppm or less

In the present invention, the amount of Al is 100 ppm or less, and the amounts of N, S, and Se are 50 ppm or less, respectively, which is essential for satisfactorily secondary recrystallization of the steel sheet. Although it is preferable to reduce these components as much as possible from the viewpoint of the magnetic properties, the reduction of these components increases the cost, and there is no problem even if the components remain within the above range.

Among them, Al and Se are elements that are difficult to be removed (purified) from the steel by finish annealing or the like, so that Al is 80 ppm and Se is more preferably 20 ppm or less. Moreover, it is common to contain 20 ppm or more and 6 ppm or more industrially, respectively.

In addition, N and S which are light elements are hard to remove completely at the time of the component adjustment before steel slab manufacture, and when it does not perform a special treatment, it is common to remain in the steel plate about 20 ppm, respectively.

Among these impurities, it is essential for the above-mentioned reason that the mass ratio (Al / N) of Al and N is 1.4 or more, and in particular, when Al / N is 2.0 or more, the magnetic properties are improved, which is more preferable. In addition, as described above, since N is difficult to remove completely, a small amount of Al may be added in a range of 100 ppm or less in order to satisfy Al / N ≧ 1.4.

Although the upper limit of Al / N is unnecessary from a viewpoint of an effect, the lower limit of the above-mentioned industrial N amount is from 20 ppm to a degree which generally does not exceed 5.

1 type, or 2 or more types selected from B, Nb, and V: 10 to 150 ppm in total

In addition, in order to fully acquire the effect of the improvement of the magnetic properties in this invention, it is necessary to add 10 ppm or more of 1 type, or 2 or more types of B, Nb, and V. FIG. The reason is as described above. When the sum total of addition amount is less than 10 ppm, the addition effect is small. Preferably, when each addition amount is 10 ppm or more, the effect of this invention can be acquired more reliably. More preferably, they are each 20 ppm or more. However, these trace additive elements remain in the ground iron also in the final product and cause deterioration of iron loss, so they are limited to 150 ppm or less in total amount. From the viewpoint of suppressing iron loss deterioration, the total amount is preferably 100 ppm or less, more preferably 50 ppm or less.

The most preferable element is Nb, which is superior to the others in the effect of uniformizing the crystal grain size after recrystallization annealing.

As mentioned above, although the essential element and the suppression element were demonstrated, in this invention, at least 1 sort (s) chosen from Ni, Cr, Cu, P, Sn, Sb, Bi, and Mo as a magnetic property improvement element suitably in the following ranges suitably. It can be contained.

Ni: 0.01% to 1.50%

Ni is an element useful in improving the hot rolled sheet structure to improve magnetic properties, but the addition effect is insufficient when the added amount is less than 0.01%. On the other hand, when it exceeds 1.50%, secondary recrystallization will become unstable and magnetic property will fall. Preferably it is 0.010% or more.

Cr: 0.01% to 0.50%, Cu: 0.01% to 0.50%, P: 0.005% to 0.50%

These elements are all useful for the improvement of iron loss, and if they fall below the lower limit, the addition effect is insufficient. On the other hand, when the upper limit is exceeded, the development of secondary recrystallized particles is suppressed, and rather, the deterioration of magnetic properties is caused.

Sn: 0.005 to 0.50%, Sb: 0.005 to 0.50%, Bi: 0.005 to 0.50%, Mo: 0.005 to 0.10%

These elements are also useful elements for improving magnetic properties, and if they fall below the lower limit, the effect of addition thereof is insufficient. On the other hand, when the upper limit is exceeded, the development of secondary recrystallized particles is suppressed, and rather, the deterioration of magnetic properties is caused. The upper limit of Mo is preferably 0.100% or less.

Next, the manufacturing process of this invention is demonstrated.

The molten steel adjusted to the above-mentioned suitable component composition is made into a slab by a conventional ingot method or a continuous casting method. Moreover, you may manufacture the thin casting piece which has a thickness of 100 mm or less by the direct casting method. In the case of a slab, although it hot-rolls by heating by a conventional method, you may provide for hot-rolling immediately, without heating after casting. In the case of a thin casting piece, hot rolling may be carried out, and hot rolling may be abbreviate | omitted and it may advance to a subsequent process as it is.

The slab heating temperature before hot rolling reduces the Al, N, S, and Se, and since it is a component system which does not contain an inhibitor component, it does not require the high temperature annealing for solidifying the inhibitor which was conventionally required. Therefore, it is preferable to set it as low temperature below 1250 degreeC from a cost point of view.

Next, hot-rolled sheet annealing is performed as needed. It is preferable to set it as about 800-1150 degreeC as a hot-rolled sheet annealing temperature in order to acquire favorable magnetic characteristics. If the hot-rolled sheet annealing temperature is lower than 800 ° C., band texture due to hot rolling remains, and it is difficult to realize a grained primary recrystallized structure, and the development of secondary recrystallization is inhibited (hot rolled sheet Pre-existing band tissue that requires annealing). On the other hand, when the hot-rolled sheet annealing temperature exceeds 1150 ° C, the grain size after the hot-rolled sheet annealing becomes excessively coarse, which is very disadvantageous in realizing the established primary recrystallized structure.

After hot-rolled sheet annealing, after performing one or more times cold rolling which has an intermediate annealing in between, recrystallization annealing is performed. In the case of cold rolling, the temperature is increased to 100 to 300 ° C, and it is advantageous to improve the magnetic properties once or a plurality of times of the aging treatment at 100 to 300 ° C during the cold rolling.

The recrystallization annealing may be carried out in a dry atmosphere when decarburization is required but the atmosphere is a wet atmosphere. The crack temperature in the recrystallization annealing is not particularly limited as long as it is higher than or equal to the recrystallization temperature. However, when annealing at an excessively high temperature results in coarse crystal grain size and secondary recrystallization, the upper limit of the annealing temperature is about 1050 ° C. desirable. Moreover, you may use together the technique which increases the amount of Si by the immersion method after recrystallization annealing.

In this invention, in the said recrystallization annealing process, it is very preferable to make the average temperature increase rate from 600 degreeC to 800 degreeC to 15 degreeC / s or more. This means that by setting the average value of the temperature increase rate to 15 ° C./s or more, as shown in FIG. 5, the standard deviation when the average particle diameter is normalized to 1.0 is very small, that is, the variation in the particle diameter is very small, resulting in excellent magnetic properties. This is because it becomes more visibly advantageous in obtaining the characteristics stably. Moreover, there is no restriction | limiting in particular about the upper limit of this average temperature increase rate, It is more preferable, but from a viewpoint of temperature control, it is preferable to adjust a temperature increase rate in 300 degrees C / s or less range. The average temperature increase rate may be obtained by dividing the amount of temperature increase (200 ° C.) by the time from reaching the temperature of 600 ° C. to 800 ° C. by measuring the surface temperature of the plate with a radiation thermometer.

Subsequently, in the case of forming a forsterite film by focusing on iron loss, after applying an annealing separator mainly composed of MgO, a final annealing is performed to develop a secondary recrystallized structure and to form a forster. A light film can be formed.

On the other hand, when punching workability is considered and a forsterite film is not formed, an annealing separator is not used, or the thing which uses silica, alumina, etc. which inhibits formation of a forsterite film even if it uses is used as a main component. When apply | coating these annealing separators, electrostatic coating which does not carry in water, etc. are effective, and a heat resistant inorganic material sheet (silica, alumina, mica) may be used.

It is preferable to perform finish annealing at 800 degreeC or more for secondary recrystallization expression. Moreover, in order to complete secondary recrystallization, it is preferable to hold at the temperature of 800 degreeC or more for 20 hours or more. In the case where the punchability is not considered and a forsterite film is not formed, secondary recrystallization may be completed. Therefore, the holding temperature is preferably about 850 ° C to 950 ° C, and the finish annealing may be finished in the holding step. In the case of focusing on iron loss or in forming a forsterite coating to reduce the noise of the transformer, it is preferable to raise the temperature to about 1200 ° C.

In addition, in the present invention, it is not necessary to remove the inhibitor in the finish annealing, and thus the degree of freedom of the finish annealing temperature is high, but it is still preferable to remove (purify) the impurities by the finish annealing even if the inhibitor is not an inhibitor. Therefore, also in this invention, finish annealing also has the meaning of a refined annealing.

After finishing annealing, water washing, brushing, acid washing and the like are carried out to remove the unreacted annealing separator attached. After that, flattening annealing to correct the shape is effective for reducing iron loss.

In addition, when laminating and using a steel plate, it is effective to apply an insulation coating to the steel plate surface before or after planarization annealing for the purpose of improving iron loss. It is preferable to make this insulation coating the coating which can give tension to a steel plate in order to reduce iron loss. That is, when the tension coating application method through a binder, the coating method which deposits an inorganic substance on the surface of a steel plate by a physical vapor deposition method, and a chemical vapor deposition method is employ | adopted, the coating film excellent in adhesiveness will be obtained and the iron loss reduction effect will also improve.

Example

(Example 1)

C: 0.018 to 0.023%, Si: 3.20 to 3.40%, Mn: 0.10 to 0.15%, Cr: 0.03 to 0.05%, Al: 30 to 140 ppm and N: 29 to 50 ppm, and the Al shown in Table 1 A steel slab having a / N ratio and containing the amounts of Nb shown in Table 1, the balance being made of Fe and unavoidable impurities, was produced by continuous casting. Subsequently, slab heating was performed at 1200 degreeC, and it was set as the hot rolled sheet of 2.2 mm of plate | board thickness by hot rolling. Next, hot-rolled sheet annealing was performed at 1060 degreeC for 40 second, and it finished by thickness of 0.23 mm of plate | board thickness by one cold rolling. Furthermore, after recrystallization annealing with crack conditions of 850 ° C. for 100 seconds was applied, an annealing separator mainly composed of MgO was applied, and then maintained at 900 ° C. for 50 hours to undergo secondary recrystallization, followed by holding at 1200 ° C. for 10 hours. An austenite film was formed. Finally, the flattening annealing was performed at 1200 degreeC for 60 second, Then, TiN was vapor-deposited on the steel plate surface by chemical vapor deposition, and it was set as the coating.

Here, the magnetic characteristic measurement sample and the magnetic characteristic measurement in the present Example were performed in the following procedures.

First, iron loss is measured over the entire length of the coil by an inline iron loss meter provided on the exit side of the annealing path of the flattening annealing line, and an iron loss profile in the coil length direction is obtained. Next, after TiN coating, a sample is taken from the site | part where the iron loss in the said iron loss profile was high, from a total of 5 points of 3 points in a plate width direction, and 2 points of both ends of a coil longitudinal direction (center of a width direction), The characteristic was measured based on the method of JISC2550.

The five points of the magnetic flux density (B ₈₎ and W _17/50, and as a representative value of the coil and excellent magnetic properties in the coil in full length by a good or bad (良否) of its value at the magnetic properties bad sample Whether or not was obtained was evaluated.

The above measurement evaluation result is written together in Table 1.

As shown in the table, according to the present invention, it was possible to obtain a grain-oriented electrical steel sheet having good magnetic properties over the entire length of the coil in the component system containing no inhibitor.

(Example 2)

C: 0.018 to 0.023%, Si: 3.20 to 3.40%, Mn: 0.10 to 0.15%, Cr: 0.03 to 0.05%, Al: 30 to 140 ppm and N: 29 to 50 ppm, and the Al / N ratio is shown in the table. It becomes the value shown in 2, and contains Nb of the quantity shown in Table 2, and remainder manufactures the steel slab which consists of Fe and an unavoidable impurity by continuous casting, heats slab at 1200 degreeC, and then hot-rolls by 2.2. It was made into a hot rolled sheet of mm thickness, and then after hot-rolled sheet annealing for 40 seconds at 1060 degreeC, it finished by cold rolling to the final plate thickness of 0.23 mm. Thereafter, recrystallization annealing was performed at 820 ° C. for 90 seconds in a humid atmosphere of 25% N ₂ -75% H ₂ . At this time, all the average temperature increase rates between 600-800 degreeC were 36 degreeC / s. In addition, all the standard deviations of the particle size distribution of the recrystallized particle were about 0.21. Next, after apply | coating the annealing separator which mainly uses MgO, the pure annealing was performed at 1200 degreeC for 10 hours. Then, planarization annealing was performed at 1200 ° C. for 60 seconds. At that time, TiN was deposited on the steel sheet surface layer by chemical vapor deposition to obtain a coating.

After planarization annealing, the iron loss of the entire length of the coil was measured in advance by an in-line iron loss meter, and samples of a total of five points including the point: three points and the two ends of the coil: two points where the iron loss was bad in the total length measurement were taken.

The magnetic properties of the obtained samples (magnetic flux density (B _8), the iron loss W _17/50) was measured by the method described in JIS C 2550, was on the other hand, the value of the magnetic properties of the five points as a representative value of the coil. In this method, since a representative value worsens when the deviation of a magnetic characteristic is large, it can be considered that the deviation in a coil can also be quantified.

The obtained results are written together in Table 2.

As is clear from the table, it is understood that good magnetic properties are obtained by adding an appropriate amount of Nb as a trace element and adjusting the Al / N ratio to an appropriate range.

(Example 3)

The steel slab containing the component shown in Table 3 and remainder which consists of Fe and an unavoidable impurity was produced by continuous casting. Subsequently, slab heating was performed at 1250 degreeC, and it was set as the hot rolled sheet of 2.3 mm of plate | board thickness by hot rolling. Next, 35 second hot-rolled sheet annealing was performed at 1000 degreeC, and it was set as the steel plate of 0.82 mm of plate | board thickness by the 1st cold rolling. Subsequently, after performing an intermediate annealing of 40 second at 1000 degreeC, it finished by the 2nd cold rolling to the final thickness of 0.23 mm of plate | board thickness. Subsequently, 60 seconds of recrystallization annealing was performed at 850 ° C, an annealing separator mainly containing MgO was applied, and finish annealing was performed at 1250 ° C for 10 hours. At this time, the second half of the holding period of 10 hours was set to Ar atmosphere, and other than that to hydrogen atmosphere. Finally, the planarization annealing which combined the formation of the tension provision coating mainly containing magnesium phosphate and boric acid was performed at 900 degreeC for 15 second.

The magnetic properties of the obtained sample were measured and evaluated for the steel sheet after annealing in the same procedure as in Example 1.

The results are written together in Table 3.

As shown in the table, according to the present invention, it was possible to obtain a grain-oriented electrical steel sheet having good magnetic properties over the entire length of the coil in the component system containing no inhibitor.

(Example 4)

The steel slab which becomes the component composition shown in Table 4 was manufactured by continuous casting, and it was set as the hot rolled sheet of 2.8 mm thickness by hot rolling after slab heating of 1200 degreeC. Subsequently, it was made into the intermediate plate thickness of 2.0 mm by the 1st cold rolling, and it finished to the final plate thickness of 0.23 mm by the 2nd cold rolling after the intermediate annealing of 1000 degreeC and 40 second. Thereafter, recrystallization annealing was performed at 830 ° C. for 60 seconds in a humid atmosphere of 40% N ₂ -60% H ₂ . At this time, all the average temperature increase rates between 600-800 degreeC were 70 degreeC / s. In addition, all the standard deviations of the particle size distribution of the recrystallized particle were about 0.19. Next, after apply | coating the annealing separator which mainly uses MgO, the pure annealing was performed at 1250 degreeC for 10 hours. At that time, the latter half of 5 hours was maintained in an Ar atmosphere, and otherwise, a hydrogen atmosphere was used. Thereafter, planarization annealing serving as a tension imparting coating mainly composed of magnesium phosphate and boric acid was performed at 900 ° C. for 15 seconds.

After planarization annealing, the iron loss of the entire length of the coil was measured in advance by an in-line iron loss meter, and samples of a total of five points including the point: three points and the two ends of the coil: two points where the iron loss was bad in the total length measurement were taken.

The magnetic properties of the obtained samples (magnetic flux density (B _8), the iron loss W _17/50) was measured by the method described in JIS C 2550, was on the other hand, the value of the magnetic properties of the five points as a representative value of the coil. In this method, since a representative value worsens when the deviation of a magnetic characteristic is large, it can be considered that the deviation in a coil can also be quantified.

The obtained results are written together in Table 4.

As is clear from the table, all the inventive examples in which the component composition satisfies the appropriate range of the present invention have obtained good magnetic properties.

(Example 5)

C: 0.082%, Si: 3.30%, Mn: 0.07%, Cr: 0.05%, P: 0.012%, Sn: 0.054%, Sb: 0.035%, Al: 70 ppm, N: 32 ppm (Al / N = 2.19 ) And V: 40 ppm, and the balance was produced by continuous casting a steel slab made of Fe and unavoidable impurities, and after heating the slab at 1200 ° C., to a hot rolled sheet having a thickness of 2.7 mm. Subsequently, after hot-rolled sheet annealing for 30 seconds at 950 degreeC, it finished to the final plate thickness of 0.30 mm by 150 degreeC warm rolling. Thereafter, recrystallization annealing was performed at 835 ° C for 90 seconds in a humid atmosphere of 60% N ₂ -40% H ₂ . At this time, the average temperature increase rate between 600-800 degreeC was variously changed as shown in Table 5. Next, after apply | coating the annealing separator which mainly uses MgO, the pure annealing was performed at 1200 degreeC for 25 hours. Thereafter, planarization annealing serving as a tension imparting coating mainly composed of magnesium phosphate and boric acid was performed at 900 ° C. for 15 seconds.

After planarization annealing, the iron loss of the entire length of the coil was measured in advance by an in-line iron loss meter, and samples of a total of five points including the point: three points and the two ends of the coil: two points where the iron loss was bad in the total length measurement were taken.

The magnetic properties of the obtained samples (magnetic flux density (B _8), the iron loss W _17/50) was measured by the method described in JIS C 2550, was on the other hand, the value of the magnetic properties of the five points as a representative value of the coil. In this method, since a representative value worsens when the deviation of a magnetic characteristic is large, it can be considered that the deviation in a coil can also be quantified.

The obtained results are written together in Table 5.

As is clear from the table, it is understood that even better magnetic properties are obtained by setting the average temperature increase rate between 600 ° C and 800 ° C to 15 ° C / s or more in the recrystallization annealing step. In addition, when the average temperature increase rate is less than 15 ° C / s, the magnetic properties deteriorate due to the deviation. In this case, the magnetic properties can be improved by making Al / N 1.4 or more and containing a predetermined amount of trace elements.

Industrial availability

According to the present invention, in the component system containing no inhibitor, the variation in the magnetic properties in the longitudinal direction and the width direction of the coil can be reduced, and as a result, good magnetic properties can be obtained as the whole product coil. That is, a grain-oriented electrical steel sheet having excellent magnetic properties over the entire length and width of the coil can be obtained, and the grain-oriented electrical steel sheet is very effective for providing for applications such as iron cores of coils requiring a strong magnetic flux density.

Claims (8)

In mass%, C: 0.10% or less, Si: 2.0% to 8.0% and Mn: 0.005% to 1.0%, Al is 100 ppm or less, and N, S and Se are each 50 ppm or less, and the balance is Fe. And a slab made of unavoidable impurities to finish to a final plate thickness, and then subjected to recrystallization annealing, followed by a series of steps in which final annealing is performed.
The ratio of the amount of Al and the amount of N contained in the slab is 1.4 or more in mass ratio, and 10 to 150 ppm of one or two or more selected from B, Nb and V is further contained in the slab in total. The manufacturing method of the grain-oriented electrical steel sheet characterized by the above-mentioned. The method of claim 1,
The above-mentioned step of rolling the slab and finishing the final sheet thickness is a step of hot rolling the slab, performing hot-rolled sheet annealing as necessary, and then carrying out two or more cold rolling with one or intermediate annealing in between. Method of manufacturing electrical steel sheet. The method according to claim 1 or 2,
Ni: 0.01-1.50%, Cr: 0.01-0.50%, Cu: 0.01-0.50%, P: 0.005-0.50%, Sn: 0.005-0.50%, Sb: 0.005-0.50% And Bi: 0.005 to 0.50% and Mo: at least one selected from 0.005 to 0.10%. The method for producing a grain-oriented electrical steel sheet characterized by the above-mentioned. In mass%, C: 0.10% or less, Si: 2.0% to 8.0%, and Mn: 0.005% to 1.0%, further, Al is 100 ppm or less, and N, S, Se are respectively reduced to 50 ppm or less, In the manufacturing method of the grain-oriented electrical steel sheet which consists of a series of process which rolls the slab which consists of Fe and an unavoidable impurity, finishes to a final board thickness, performs recrystallization annealing, and then performs final annealing,
Further, in the slab, one or two or more selected from B, Nb, and V are contained in the range of 10 to 150 ppm in total, and the ratio of Al and N is Al / N ≧ 1.4 in mass ratio, and The average temperature increase rate between 600-800 degreeC in recrystallization annealing is 15 degreeC / s or more, The manufacturing method of the grain-oriented electrical steel sheet characterized by the above-mentioned. The method of claim 4, wherein
The above-mentioned step of rolling the slab and finishing the final sheet thickness is a step of hot rolling the slab, performing hot-rolled sheet annealing as necessary, and then carrying out two or more cold rolling with one or intermediate annealing in between. Method of manufacturing electrical steel sheet. The method according to claim 4 or 5,
Ni: 0.010 to 1.50%, Cr: 0.01 to 0.50%, Cu: 0.01 to 0.50%, P: 0.005 to 0.50%, Sn: 0.005 to 0.50%, Sb: 0.005 to 0.50% And Bi: 0.005 to 0.50% and Mo: at least one selected from 0.005 to 0.100%. The method for producing a grain-oriented electrical steel sheet characterized by the above-mentioned. The method according to claim 4 or 5,
A particle size distribution of recrystallized particles of a steel sheet after recrystallization annealing satisfies a standard deviation of 0.3 or less when the average particle diameter is standardized to 1.0. The method according to claim 6,
A particle size distribution of recrystallized particles of a steel sheet after recrystallization annealing satisfies a standard deviation of 0.3 or less when the average particle diameter is standardized to 1.0.

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