JP2012184497A - Method for producing grain-oriented electromagnetic steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a novel method for producing a grain-oriented electromagnetic steel sheet by which texture modification effect same as that of warm rolling can be attained.SOLUTION: Steel slab containing 0.01-0.10 mass% C, 2.0-4.5 mass% Si and 0.01-0.5 mass% Mn is hot-rolled to produce a hot-rolled plate, and the hot-rolled plate is annealed. Then, the hot-rolled plate is rolled at rolling-reduction ratio of 85% or more by one-time cold rolling, or it is rolled at rolling-reduction ratio of 80% or more by finish cold rolling comprising two or more times cold rolling with intermediate annealing, to produce a cold-rolled plate having a final plate thickness. The cold-rolled plate is subjected to primary recrystallize-annealing and secondary recrystallize-annealing to obtain the grain-oriented electromagnetic steel sheet. In the method for producing the grain-oriented electromagnetic steel sheet, low strain rate cold rolling of 150sor less in strain rate is conducted at least one pass or more in a step of the cold rolling in which a total rolling reduction is 50% or less.

Description

  The present invention relates to a method for producing a grain-oriented electrical steel sheet having excellent magnetic properties.

  A grain-oriented electrical steel sheet is a steel sheet having excellent magnetic properties having a crystal structure in which {110} <001> orientation (Goss orientation), which is an easy axis of iron, is highly integrated in the rolling direction of the steel sheet.

  As a method for further increasing the degree of integration in the Goss orientation, for example, Patent Document 1 discloses a method in which a cold-rolled sheet being cold-rolled is heat-treated at a low temperature and subjected to an aging treatment. Patent Document 2 discloses that the cooling rate during hot-rolled sheet annealing or intermediate annealing before final cold rolling is set to 30 ° C./sec or more, and the plate temperature is 150 to 300 ° C. during final cold rolling. A technique for performing aging between passes of more than one minute twice or more is disclosed. Further, Patent Document 3 discloses a technique that utilizes the effect of dynamic strain aging in which dislocations introduced during rolling are immediately fixed by C or N by increasing the temperature of the steel sheet during rolling and performing warm rolling. Has been.

  In any of these techniques of Patent Documents 1 to 3, carbon (C) and nitrogen (N), which are solid solution elements, are diffused at a low temperature by maintaining the steel sheet temperature at an appropriate temperature during rolling or between rolling passes. It is intended to improve the rolling texture by fixing the dislocations introduced in the cold rolling, preventing the movement of the dislocations in the subsequent rolling, and causing more shear deformation. By applying these techniques, the <110> fiber structure called the α fiber in the primary recrystallization texture after cold rolling, in particular, the {001} <110> orientation is reduced, and the <111> called the γ fiber. Increasing the frequency of the Goss orientation {110} <001> while reducing the fiber structure makes it possible to increase the degree of integration in the Goss orientation after secondary recrystallization.

  As the rolling method used for the cold rolling, there are reverse rolling (Patent Document 4 and the like) and tandem rolling (Patent Document 5 and the like), and the latter reverse rolling is performed many times by rolling and winding. Since it is repeatedly performed, it is maintained at an appropriate temperature in a coil state during rolling, and the same effect as a so-called aging treatment can be obtained, which is advantageous in terms of magnetic characteristics.

  By the way, the grain-oriented electrical steel sheet hot-rolls a steel material (steel slab) containing about 4.5 mass% or less of Si, and further containing a component forming AlN, MnS, MnSe, or the like called an inhibitor. In general, it is manufactured by cold rolling, primary recrystallization annealing, and secondary recrystallization in finish annealing.

In addition to the above method, a technique (inhibitorless method) for causing secondary recrystallization without containing an inhibitor component has also been proposed (for example, Patent Document 6). This technique has the advantage that a grain-oriented electrical steel sheet can be produced at low cost because it does not require high-temperature slab heating to dissolve the inhibitor component, and does not require purification by finish annealing. However, this technology uses a higher purity steel and is a technology that expresses secondary recrystallization due to the effect of suppressing normal grain growth by texture (texture) control. More delicate control is required.
As described above, texture control during cold rolling is extremely important in producing grain-oriented electrical steel sheets having excellent magnetic properties regardless of whether or not an inhibitor is used.

  Patent Documents 7 to 11 disclose techniques for improving the primary recrystallization texture by rapid heating at the time of decarburization annealing or rapid heating treatment immediately before the decarburization annealing. In addition, it is possible to increase the presence frequency of the Goss orientation {110} <001> while reducing the γ fiber of the primary recrystallization texture. For example, Patent Document 8 discloses cold rolling containing C: 0.10 wt% or less, Si: 2.5 to 7.0 wt%, and a normal inhibitor component, with respect to a steel sheet that has been subjected to warm rolling during rolling. A method of manufacturing a unidirectional electrical steel sheet having good iron loss characteristics by heating the plate to 700 ° C. or higher at a temperature increase rate of primary recrystallization annealing of 50 ° C./sec is disclosed.

Japanese Patent Laid-Open No. 50-016610 Japanese Patent Laid-Open No. 08-253816 Japanese Patent Laid-Open No. 01-215925 Japanese Patent Publication No. 54-013846 Japanese Examined Patent Publication No. 54-029182 JP 2000-129356 A Japanese Patent Laid-Open No. 07-062436 Japanese Patent Application Laid-Open No. 07-062437 Japanese Patent Laid-Open No. 10-298653 JP 2000-204450 A JP 2003-027194 A

  By the way, the {001} <110> structure generated in the hot-rolled sheet remains as a result of subsequent cold rolling and primary recrystallization, and is known as a structure that is hardly eroded by Goss grains. Therefore, this structure can be said to be a very disadvantageous crystal orientation when the technique of Patent Document 6 is used to develop secondary recrystallization by texture (texture texture) control. Therefore, this reduction in orientation is extremely important particularly when the inhibitor component is reduced and secondary recrystallization is caused by texture control.

  In order to reduce the {001} <110> structure in the steel sheet after the primary recrystallization annealing and form Goss nuclei, the aging effect by the above-described C and N until the final sheet thickness is obtained by cold rolling. It is effective to apply a so-called warm rolling technique in which the roll biting temperature in cold rolling is increased and the high temperature state is maintained even between passes.

  In order to apply the warm rolling technique, as described above, reverse rolling capable of winding aging is advantageous. However, since reverse rolling is a batch process, there is a drawback that productivity is inferior. On the other hand, tandem rolling, which is excellent in productivity, can achieve the same effect by increasing the interpass temperature or increasing the roll biting temperature. However, the effect is limited, and it is actually difficult to obtain the effect as much as reverse rolling.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to propose a novel method for producing grain-oriented electrical steel sheets that can provide the same texture modification effect as that of warm rolling. There is.

As described above, in order to obtain the dislocation fixing effect (aging effect) of C and N necessary for the formation of a good texture, the temperature and time for diffusing these elements are indispensable. There are many problems in realizing the effect industrially stably. Accordingly, the inventors have obtained the same effect as the aging effect of C and N, that is, other cold rolling conditions that can obtain the effect of reducing the {001} <110> structure generated in the hot-rolled sheet and the effect of forming Goss nuclei. We have been intensively studying. As a result, at the stage where the total rolling reduction in cold rolling is 50% or less, the same effect as the aging effect can be obtained by performing rolling at a low strain rate with a strain rate of 150 s ^-1 or less at least one pass. As a result, the present invention has been completed.

That is, the present invention hot-rolls a steel slab containing C: 0.01 to 0.10 mass%, Si: 2.0 to 4.5 mass%, and Mn: 0.01 to 0.5 mass%. After rolling and hot-rolled sheet annealing, rolling with a reduction ratio of 85% or more is performed by one cold rolling, or final cold rolling reduction ratio is 80 by two or more cold rolling sandwiching intermediate annealing. % Of rolled steel to obtain a cold-rolled sheet having a final thickness, and thereafter subjected to primary recrystallization annealing and secondary recrystallization annealing, the total rolling reduction in the cold rolling is 50%. In the following steps, a low-strain-rate cold rolling with a strain rate of 150 s ⁻¹ or less is performed at least one pass or more.

The manufacturing method of the grain-oriented electrical steel sheet according to the present invention is characterized in that the strain rate is 100 s ⁻¹ or less.

  The grain-oriented electrical steel sheet manufacturing method of the present invention is characterized in that the {001} <110> strength in the steel sheet structure after the low strain rate cold rolling is 10 or less.

Moreover, the manufacturing method of the grain-oriented electrical steel sheet according to the present invention is characterized by rolling at a strain rate of 400 s ⁻¹ or more after the total rolling reduction in the cold rolling exceeds 50%.

  Moreover, the manufacturing method of the grain-oriented electrical steel sheet according to the present invention is characterized in that, in the primary recrystallization annealing, a temperature rising rate between 500 to 700 ° C. is set to 50 ° C./sec or more.

  Moreover, the steel slab in the method for producing a grain-oriented electrical steel sheet according to the present invention has Al: 0.01-0.065 mass% and N: 0.005-0. It is characterized by containing S: 0.005-0.03 mass% and / or Se: 0.005-0.03 mass% as 012 mass% and / or MnS · MnSe-based inhibitor component.

  Moreover, the steel slab in the method for producing a grain-oriented electrical steel sheet according to the present invention further includes Al, N, S, and Se in addition to the above component composition, Al: 0.0100 mass% or less, N: 0.0050 mass% or less, It contains S: 0.0050 mass% or less and Se: 0.0050 mass% or less.

  Moreover, in addition to the said component composition, the said steel slab in the manufacturing method of the grain-oriented electrical steel sheet of this invention has further Ni: 0.03-1.50 mass%, Sn: 0.01-1.50 mass%, Sb: 0.005-1.50 mass%, Cu: 0.03-3.0 mass%, P: 0.03-0.50 mass%, Mo: 0.005-0.10 mass%, Nb: 0.0005-0. It is characterized by containing 1 type (s) or 2 or more types selected from 010 mass% and Cr: 0.03-1.50 mass%.

According to the present invention, in the stage where the total rolling reduction in cold rolling is 50% or less, low texture rolling at a strain rate of 150 s ⁻¹ or less is applied at least one pass, so that the texture modification similar to warm rolling is performed. Since a quality effect is obtained, it becomes possible to advantageously manufacture a grain-oriented electrical steel sheet having excellent magnetic properties.

It is a figure which shows the influence which the temperature and strain rate in the cold rolling of the 1st pass have on a texture. It is a graph which shows the influence which the strain rate in the cold rolling of the 1st pass has on {001} <110> strength. It is a graph which shows the relationship between the cold rolling reduction rate of the 1st stand in Example 1, and magnetic flux density B8 of a product board.

ここで、ｖＲはロール周速度（ｍｍ／ｓ）、Ｒ´はロール半径（ｍｍ）、ｈ１はロール入側板厚（ｍｍ）、ｒは圧下率（％）である。 First, the experiment that led to the development of the present invention will be described.
C: 0.042 mass%, Si: 3.32 mass% and Mn: 0.06 mass%, S, Se, O are each reduced to less than 0.0050 mass%, N is reduced to less than 0.0025 mass%, and the balance A steel slab composed of Fe and inevitable impurities and containing no inhibitor component was heated to 1210 ° C. and then hot-rolled to obtain a hot-rolled sheet having a thickness of 2.5 mm.
Next, the test piece taken from the hot-rolled sheet was subjected to hot-rolled sheet annealing at 1000 ° C. for 60 seconds, and then cold-rolled with a thickness of 2.0 mm (20% reduction) by one-pass cold rolling. A board was used. The cold rolling was performed by assigning the rolling temperature to two levels of 25 ° C. and 100 ° C. and the strain rate during rolling to two levels of 100 s −1 and 250 s −1. The strain rate during rolling was calculated using the following Ekelund equation.

Here, vR is the roll peripheral speed (mm / s), R ′ is the roll radius (mm), h1 is the roll entry side plate thickness (mm), and r is the rolling reduction (%).

  A 30 mm × 30 mm test piece was cut out from the cold-rolled plate thus obtained, and the thickness was reduced by mechanical grinding from one side of the test piece to 1/5 of the plate thickness. Further, the surface was chemically polished to 5 mass%. After etching with nitric acid for 10 seconds, a positive dot diagram was created by X-ray measurement, and changes in texture before and after rolling were investigated. The texture was analyzed by the ADC method to obtain ODF (crystallite orientation distribution function) in Euler space (φ2 = 45 ° cross section), and the result is shown in FIG. From FIG. 1, when the rolling temperature is 25 ° C. and the strain rate is 250 s-1 as a reference (base), the same texture as when the rolling temperature is increased to 100 ° C. by setting the strain rate to 100 s−1. It can be seen that the change is obtained.

The inventors consider the cause of the change in texture as described above as follows. First, it is clear from the fact that the rolling temperature is 25 ° C. that the texture change is not due to the aging effect due to C or N. Also, dynamic strain aging in which C or N dynamically acts on dislocation movement is difficult to think because the strain rate is 100 times faster than the diffusion rate of C or N.
However, as the strain rate decreases, the CRSS (critical decomposition shear stress) increases. This indicates that dislocations are difficult to move under the same stress condition, and it is presumed that the dislocations are fixed by C and N and are close to each other as a phenomenon. Moreover, since the strain rate dependency of CRSS differs depending on the slip surface of dislocation, the slip surface different from the strain rate in normal rolling may be activated and the deformation behavior may be changed. For these reasons, it is considered that when the strain rate is reduced, the {001} <110> structure in the texture of the steel sheet after cold rolling is reduced, and the degree of accumulation in the Goss orientation is increased.

Next, a hot-rolled sheet having a thickness of 13.2 and a {001} <110> strength of 13.2 is subjected to one pass rolling at various strain rates at a temperature of 25 ° C. Using a cold-rolled sheet with a rolling reduction of 20%, the change in {001} <110> strength was investigated in the same manner as in the above experiment. The intensity of the {001} <110> orientation is determined by preparing a positive point map by X-ray measurement, analyzing the texture by the ADC method based on the obtained positive point map, and then determining the Euler space (φ ₂ = 45 ° When the ODF is (cross section), it is expressed by numerical values of φ = 0 ° and φ ₁ = 0 °. FIG. 2 shows the results of the above experiment. As the strain rate decreases, the {001} <110> strength decreases. When the strain rate is 150 s ⁻¹ or less, the {001} <110> strength decreases. It turns out that it has fallen to 10 or less.

  As described above, the reduction in strain rate in cold rolling can be an effective means for improving the texture. However, a reduction in strain rate is not preferable from the viewpoint of productivity because it causes a reduction in rolling speed. Therefore, the inventors examined the range of the cold rolling reduction ratio in which the effect of reducing the {001} <110> orientation by reducing the strain rate and the effect of improving the integration degree in the Goss orientation are exhibited. As a result, when the final sheet thickness is obtained by one cold rolling, the total reduction in the cold rolling is performed in any case where the final sheet thickness is obtained by two or more cold rolling sandwiching the intermediate annealing. It has been found that it is effective to perform low-speed rolling when the rate is in the range of 50% or less.

This is presumably because when the cold rolling reduction ratio is high, there are many dislocations in the crystal grains, and it becomes difficult to obtain a difference in the activity of slip planes of dislocations. Therefore, in order to obtain the effect of a low strain rate, it is necessary to carry out in a state where there are few dislocations in the crystal grains, that is, at a stage where the total rolling reduction is 50% or less. On the contrary, when the rolling reduction exceeds 50%, it is more advantageous to perform high strain rate rolling from the viewpoint of productivity. Furthermore, in high-speed rolling at a strain rate of 400 s ^-1 or higher, the roll peripheral speed is increased, the amount of rolling oil drawn into the roll bite is increased, the lubricity is improved, and the rolling load is reduced. This is also advantageous for control. In particular, from the viewpoint of shape control, it is preferable to carry out in the final pass of rolling.
The present invention has been developed based on the above findings.

Next, the manufacturing method of the grain-oriented electrical steel sheet of this invention is demonstrated.
The present invention is an alternative to warm rolling in a method for producing grain-oriented electrical steel sheets that has conventionally been controlled in texture by warm rolling, and has an effect of improving magnetic properties equivalent to or higher than that of warm rolling. It intends to provide the obtained cold rolling technology. Accordingly, the steel slab (steel material) used for producing the grain-oriented electrical steel sheet of the present invention is not particularly limited as long as it is produced by a conventionally known method. For example, molten steel obtained in a converter, electric furnace, etc. is subjected to secondary refining such as vacuum degassing to obtain a desired component composition, and then the steel is melted by a generally known refining process, and then continuous casting or ingot- For example, a method of forming a steel slab by a block rolling method.

In addition, the component composition of the steel slab is basically not particularly limited as long as it is suitable for the production of a grain-oriented electrical steel sheet, but in order to obtain a grain-oriented electrical steel sheet having excellent magnetic properties, It is necessary to contain C, Si and Mn as basic components in the following range.
C: 0.01-0.10 mass%
C is an element necessary for improving the texture of the hot-rolled steel sheet. If it is less than 0.01 mass%, the structure becomes coarse during slab heating, and recrystallization hardly occurs in the subsequent steps. On the other hand, when C exceeds 0.10 mass%, it becomes difficult to reduce to 0.0050 mass% or less at which no magnetic aging occurs due to decarburization annealing. Therefore, C is set to a range of 0.01 to 0.10 mass%. Preferably, it is the range of 0.01-0.08 mass%.

Si: 2.0 to 4.5 mass%
Si is an element effective for increasing the electrical resistance of steel and improving iron loss. However, if the content is less than 2.0 mass%, a sufficient effect of reducing iron loss cannot be obtained. On the other hand, if it exceeds 4.5 mass%, the workability is remarkably lowered and it is difficult to roll and manufacture. Therefore, Si is set to a range of 2.0 to 4.5 mass%.

Mn: 0.01 to 0.5 mass%
Mn is an element necessary for improving hot workability, but if the content is less than 0.01 mass%, the above effect cannot be obtained. On the other hand, if the content exceeds 0.5 mass%, primary recrystallization aggregates are obtained. The structure deteriorates, and it becomes difficult to obtain secondary recrystallized grains highly accumulated in the Goss orientation. Therefore, Mn is set to a range of 0.01 to 0.5 mass%. Preferably, it is the range of 0.01-0.10 mass%.

  In the grain-oriented electrical steel sheet according to the present invention, when an inhibitor is used to cause secondary recrystallization, for example, when an AlN-based inhibitor is used, Al and N are each changed to Al: 0.01-0. 065 mass% and N: 0.005 to 0.012 mass% are preferably included. When a MnS · MnSe-based inhibitor is used, Se and / or S is changed to S: 0.005 to 0.005, respectively. It is preferable to make it contain in the range of 03mass%, Se: 0.005-0.03mass%.

  On the other hand, when an inhibitor is not used for causing secondary recrystallization, the inhibitor components Al, N, S and Se are Al: 0.0100 mass% or less, N: 0.0050 mass% or less, S : 0.0050 mass% or less, preferably Se: 0.0050 mass% or less.

Further, the grain-oriented electrical steel sheet of the present invention is further provided with Ni: 0.03-1.50 mass%, Sn: 0.01-1.50 mass%, Sb in addition to the above component composition for the purpose of improving magnetic properties. : 0.005 to 1.50 mass%, Cu: 0.03 to 3.0 mass%, P: 0.03 to 0.50 mass%, Mo: 0.005 to 0.10 mass%, Nb: 0.0005 to 0 You may contain 1 type (s) or 2 or more types chosen from 0.010 mass% and Cr: 0.03-1.50 mass%.
Ni is an element useful for improving the magnetic properties by improving the hot-rolled sheet structure. However, if the amount is less than 0.03 mass%, the above effect is small. On the other hand, if it exceeds 1.50 mass%, the secondary recrystallization becomes unstable and the magnetic characteristics deteriorate.
Sn, Sb, Cu, P, Mo, Nb, and Cr are elements useful for improving the magnetic properties, but any of them is less effective in improving the magnetic properties if it is less than the above lower limit value. If it exceeds, the development of secondary recrystallized grains will be inhibited, so each content is preferably within the above range.
The balance other than the above components is Fe and inevitable impurities.

  The steel slab having the above component composition is then reheated and subjected to hot rolling. In this case, the slab heating temperature is preferably 1300 ° C. or higher when the inhibitor component is contained because it is necessary to completely dissolve the inhibitor component. From the viewpoint of securing the rollability, it is preferably about 1050 ° C. or higher. In addition, there is no restriction | limiting in particular about hot rolling conditions, It can carry out according to a conventional method.

  The hot-rolled sheet obtained by hot rolling is then subjected to hot-rolled sheet annealing and then cold-rolled sheet having a final sheet thickness by one or more cold rolling or two or more cold rolling sandwiching intermediate annealing. To do. The cold rolling at this time is a total rolling reduction of 85% or more in the case of one cold rolling, and the final cold rolling reduction of 80% in the case of two or more cold rolling sandwiching the intermediate annealing. This is necessary. When the cold rolling reduction ratio is less than these values, the sharpness of the texture of the primary recrystallized texture (structure that is phagocytosed in Goss orientation; accumulation degree such as {111} <112> or {12 4 1} <014>) Decreases and it becomes difficult to cause good secondary recrystallization.

In the cold rolling of the present invention, the total rolling reduction is 50% on the basis of the thickness of the hot-rolled sheet, regardless of one cold rolling or two or more cold rollings with intermediate annealing. Until it exceeds, that is, the following formula:
Total rolling reduction = {(Hot rolled plate thickness−Cold rolled plate thickness) / Hot rolled plate thickness} × 100 (%)
It is necessary to perform low strain rate cold rolling with a strain rate of 150 s ⁻¹ or less at least one pass at a stage where the total rolling reduction represented by

In the present invention, the {001} <110> orientation is formed by hot rolling and corresponds to the main orientation before cold rolling. Therefore, by carrying out low strain rate rolling with the total rolling reduction of cold rolling being 50% or less. , {001} <110> orientation can be reduced, and the strength of the Goss orientation can be effectively increased. That is, when low strain rate cold rolling is performed at a stage where the total rolling reduction exceeds 50%, the introduced dislocation density is high, and therefore the change of the slip surface of the dislocation due to the decrease in strain rate does not occur. {001} <110> Texture improvement effects such as reduction of texture and increase of Goss nuclei cannot be obtained. From the above viewpoint, it is most effective to perform the low strain rate cold rolling with a strain rate of 150 s ⁻¹ or less in the first pass where no dislocation exists.

If the strain rate exceeds 150 s ⁻¹ , as shown in FIGS. 1 and 2, the effect of reducing {001} <110> and the effect of forming Goss nuclei cannot be obtained sufficiently. In order to further enhance the above effect, it is more preferable to set the strain rate to 100 s ⁻¹ or less. However, if the strain rate is less than 20 s ⁻¹ , the texture improving effect is saturated and only the productivity is lowered. Therefore, the lower limit is preferably about 20 s ⁻¹ . Furthermore, in the low strain rate cold rolling with a strain rate of 150 s ⁻¹ or less, it is preferable that the rolling reduction of one pass is 10% or more. This is because if the rolling reduction is less than 10%, the crystal rotation is not sufficient, and the strength of Goss nuclei may not be sufficiently increased.

In addition, the rolling texture of a steel sheet cold-rolled at a low strain rate of 150 s ⁻¹ or less or 100 s ⁻¹ or less has a strength of {001} <110> orientation (advantageous to secondary recrystallization) A positive point diagram is created, and the resulting texture is analyzed by the ADC method. The ODF of the Euler space (φ ₂ = 45 ° cross section) is φ = 0 °, φ ₁ = 0 °) is 10 or less. Preferably there is. This is because if the intensity of the {001} <110> orientation is 10 or more, the crystal orientation after secondary recrystallization deteriorates.
In addition, the rolling temperature in the cold rolling is not particularly limited. However, when the warm rolling is possible, it is preferable to implement the rolling because it is synergistic with the effect of the present invention.

  A cold-rolled sheet that has been rolled to the final sheet thickness that satisfies the above conditions can obtain an effect of improving the texture even if it is subjected to normal primary recrystallization annealing. However, by performing primary recrystallization annealing with a heating rate between 500 and 700 ° C. being 50 ° C./sec or more, the amount of Goss orientation is further increased, and the crystal grain size after secondary recrystallization is refined, It is possible to improve the iron loss characteristics.

  As described above, the present invention is a technique for effectively reducing the {001} <110> structure and increasing the strength of the Goss orientation by appropriately controlling the cold rolling. When rapidly heating at a heating rate of 500 to 700 ° C. at 50 ° C./sec or higher in the temperature raising process, increasing the existence ratio of the Goss orientation while slightly reducing the γ fiber (<111> fiber structure). Can do. Increasing the temperature increase rate of primary recrystallization annealing to 50 ° C./sec or more does not contribute to the reduction of {001} <110> structure, but has the effect of increasing the existence ratio of Goss orientation. It becomes possible to refine the next recrystallized grain size and obtain a low iron loss. The rapid heating is intended to rapidly reheat and recrystallize the temperature range corresponding to the recovery of the structure after cold rolling, so the temperature range is between 500 to 700 ° C., which is the recovery range of the structure. And However, if the rate of temperature rise is less than 50 ° C./sec, recovery in the above temperature range cannot be sufficiently suppressed.

In general, primary recrystallization annealing often serves also as decarburization annealing. In this case, the atmosphere during annealing is preferably an appropriate oxidizing atmosphere (for example, PH ₂ O / PH ₂ > 0.1). Note that the inter-500 to 700 ° C. required high heating rate, it is considered can be difficult to oxidizing atmosphere by constraints such as facilities, the atmosphere in the temperature range PH _{2 O /} PH 2 ≦ 0 1 may be used, and decarburization annealing may be performed again separately from the primary recrystallization annealing.

The steel sheet subjected to primary recrystallization annealing is then subjected to finish annealing for applying secondary annealing to the steel sheet surface after applying an annealing separator. As the annealing separator, conventionally known ones can be used. For example, MgO is the main component, and if necessary, TiO ₂ or the like is added, or SiO ₂ or Al ₂ O ₃ is the main component. Can be used.

The steel sheet after the above-mentioned finish annealing is then preferably applied with an insulating film on the steel sheet surface and baked, and then flattened and annealed to adjust the steel sheet shape as necessary. The type of the insulating coating is not particularly limited. However, when forming an insulating coating that imparts tensile tension to the steel sheet surface, Japanese Patent Laid-Open Nos. 50-79442 and 48-39338 are disclosed. It is preferable to bake at about 800 ° C. using a coating solution containing phosphate-chromic acid-colloidal silica described in the above. In addition, when a material mainly composed of SiO ₂ or Al ₂ O ₃ is used as the annealing separator, a forsterite film is not formed on the surface of the steel sheet after finish annealing, so that water containing MgO as a main component is newly formed. The insulating film may be formed after the slurry is applied and annealed to form a forsterite film.

C: 0.050 mass%, Si: 3.3 mass%, and Mn: 0.04 mass%, S, Se, and O are each contained less than 0.0050 mass%, N is contained less than 0.0025 mass%, and the balance A steel slab having a composition of Fe and inevitable impurities and containing no inhibitor component was heated to 1100 ° C. and hot-rolled to obtain a hot-rolled sheet having a thickness of 2.0 mm. Subsequently, the hot-rolled sheet was subjected to hot-rolled sheet annealing at 1000 ° C. for 70 seconds, and then cold-rolled with a 4-stand tandem rolling mill having a roll diameter of 300 mmφ, and the final sheet thickness was 0.29 mm (total rolling reduction) 86%). In the cold rolling, as shown in Table 1, the rolling of the first one stand and 35% rate reduction, changing the strain rate ^{80s -1,} the four levels of 120s -1, 160s ^-1 and 200 s ^-1 I let you. Note that the strain rate after 2 stands is naturally determined if the strain rate of 1 stand and the reduction rate distribution after 2 stands are determined.

  The cold-rolled sheet is then subjected to primary recrystallization annealing also serving as decarburization annealing with a soaking temperature of 840 ° C. and a soaking time of 100 seconds, and then an annealing separator mainly composed of MgO on the steel sheet surface. Then, finish annealing is performed to perform secondary recrystallization, and then the surface of the steel sheet after the secondary recrystallization annealing contains phosphate-chromate-colloidal silica in a weight ratio of 3: 1: 2. The coating liquid to be applied was applied, and flattening annealing was performed at 800 ° C. for 30 seconds to obtain a product coil.

Thereafter, an Epstein test piece having a width of 30 mm and a length of 280 mm is cut out from the center in the length direction and the width in the center of each product coil, and a total weight of 500 g or more is cut out. the magnetic flux density _{B 8} were measured.
The result of the measurement is shown in FIG. From FIG. 3, it can be seen that the magnetic flux density B ₈ is greatly improved by rolling at one stand, that is, at a stage where the total rolling reduction is 50% or less, at a strain rate of 150 s ⁻¹ or less.

A sample was cut out from the cold-rolled coil produced in Example 1, and the heating rate between 500 to 700 ° C. was divided into two levels of 30 ° C./sec and 100 ° C./sec and heated, and PH ₂ O / PH ₂ = In an atmosphere of 0.32, primary recrystallization annealing was performed by soaking at 900 ° C. for 50 seconds. Note that some samples were subjected to primary recrystallization annealing at 900 ° C. for 50 seconds in an atmosphere of PH ₂ O / PH ₂ = 0.01. In this case, separately after the primary recrystallization annealing, PH ₂ O / PH ₂ = 0.30, and decarburization annealing was performed at 820 ° C. for 30 seconds.
Then, after applying an annealing separator mainly composed of MgO to the surface of the sample (steel plate), finish annealing is performed to cause secondary recrystallization, and then the surface of the steel plate after the secondary recrystallization annealing is subjected to phosphoric acid. A coating solution containing salt-chromate-colloidal silica at a weight ratio of 3: 1: 2 was applied, and flattening annealing was performed at 800 ° C. for 30 seconds to obtain a product coil.
Thereafter, an Epstein test piece having a width of 30 mm and a length of 280 mm from the center in the length direction and the center in the width direction of each product coil was cut out in a total weight of 500 g or more, and magnetic flux density B ₈ and iron loss W _{17 / 50} was measured and the results are shown in Table 2.

From Table 2, the magnetic flux density B ₈ is good under the conditions suitable for the present invention in which the low strain rate rolling of 150 s ⁻¹ or less was performed on a rolling stand corresponding to a total rolling reduction of 50% or less, and in particular, primary recrystallization. It can be seen that the iron loss W _17/50 is very good under the conditions where the temperature elevation rate of annealing is 50 ° C./sec or more.

Steel slab containing C: 0.030 mass%, Si: 3.34 mass% and Mn: 0.08 mass%, Al: 0.0250 mass% and N: 0.0080 mass%, and further containing an inhibitor component After heating to 1350 ° C. and hot rolling to obtain a hot-rolled sheet having a thickness of 2.4 mm, six hot-rolled coils subjected to hot-rolled sheet annealing at 1060 ° C. × 10 seconds were prepared. Next, as shown in Table 3, the hot-rolled coil was 1.2 mm (rolling ratio 50%) using a reverse rolling mill having a roll diameter of 60 mmφ and a 4-stand tandem rolling mill having a roll diameter of 300 mmφ. The first half was cold-rolled to an intermediate thickness. In the reverse rolling, rolling was performed by two-pass rolling with a strain rate of 150 s ⁻¹ or more, and in tandem rolling, the strain rate of each pass was 100 s ⁻¹ or less.
A sample of 100 mm square was cut out from the coil width center part of the intermediate plate thickness obtained as described above, X-ray measurement was performed, and analysis was performed by the ADC method from the obtained positive electrode dot diagram, and Euler space (φ ₂ = 45 ° The values of φ = 0 ° and φ ₁ = 0 ° as the ODF of the (cross section) were taken as the intensity of the {001} <110> orientation.

Next, the cold rolled sheet coil (5 passes) in the latter half using a reverse rolling mill with a roll diameter of 60 mmφ after or without performing intermediate annealing at 1050 ° C. for 20 seconds on the cold rolled sheet coil having the intermediate sheet thickness. To obtain a cold-rolled sheet having a final sheet thickness of 0.22 mm (rolling ratio 82%). In the latter half of the cold rolling, the strain rate was divided into two levels: high speed rolling at 400 s ⁻¹ or higher and low speed rolling at 150 s ⁻¹ or lower.
Next, after subjecting the cold-rolled sheet having the above final thickness to primary recrystallization annealing at a soaking temperature of 900 ° C. and a soaking time of 20 seconds, an annealing separator containing Al ₂ O ₃ as a main component is applied to the steel sheet surface. After the application, finish annealing was performed for secondary recrystallization. In addition, since the forsterite film is not formed on the surface of the steel sheet after the finish annealing, after applying a slurry containing MgO as a main component and performing film formation annealing, the phosphate-chromate is further added. -The coating liquid which contains colloidal silica by weight ratio 3: 1: 2 was apply | coated, and the flattening annealing of 800 degreeC x 30 second was given, and it was set as the product coil.

From the longitudinal central portion and the widthwise central portion of each product coil obtained as described above, cut out above 500g Epstein test piece width 30 mm × length 280 mm, the magnetic flux density was measured B ₈ by Epstein test.
The results are shown in Table 3. From Table 3, No. was obtained by cold rolling a stage with a total rolling reduction of 50% or less at a low strain rate (<100 s ⁻¹ ). The steel plates 1 to 3 were No. ¹ cold-rolled at high strain rates (> 150 s ⁻¹ ). 4-6 in comparison with steel, it can be seen that show good magnetic flux density B _8. However, no. The steel plate No. 3 has a low {001} <110> strength during rolling and good magnetic properties (B ₈ ) of the product plate, but has a poor lubricity and poor shape due to the low cold rolling speed in the latter half. Occurred.

C: 0.040 mass%, Si: 3.3 mass%, Mn: 0.05 mass%, Se: 0.02 mass%, and other components include Ni, Sn, Sb, Cu, P, Mo, Nb and Steel containing Cr with the composition shown in Table 4 is melted to form a steel slab, heated to 1400 ° C., hot-rolled to a hot-rolled sheet having a thickness of 2.2 mm, and heat at 1000 ° C. for 60 seconds. The steel sheet was annealed. Subsequently, the hot rolled sheet was subjected to cold rolling in the first half using a 4-stand tandem rolling mill having a roll diameter of 280 mmφ, with the strain rate of the first stand being less than 100 s ⁻¹ , and 1.5 mm (reduction rate of 32% ) Intermediate plate thickness. At this time, as a comparative example, one of the coils not containing Ni, Sn, Sb, Cu, P, Mo, Nb, and Cr was rolled from a 2.2 mm hot rolled plate to an intermediate plate thickness of 0.8 mm. It rolled with the reverse rolling mill of diameter 100mmphi.
Next, after intermediate annealing at 1050 ° C. × 20 seconds, cold rolling in the latter half was performed using a reverse rolling mill having a roll diameter of 100 mmφ, and a cold-rolled sheet having a final sheet thickness of 0.22 mm (reduction rate of 85%) It was. Incidentally, the strain rate of the reverse rolling mill, rolling in five passes, each pass is also the strain rate was 400 ^-1.
Then, after subjecting the cold-rolled sheet to primary recrystallization annealing at 850 ° C. for 40 seconds, an annealing separator mainly composed of MgO is applied to the steel sheet surface, finish annealing is performed, and the obtained secondary recrystallization is performed. A coating solution containing phosphate-chromic acid salt-colloidal silica in a mass ratio of 3: 1: 2 is applied to the steel plate, and subjected to flattening annealing that combines baking and flattening at 850 ° C. for 30 seconds. The product coil.

A test piece of 30 mm × 280 mm was cut out from the position of the center in the length direction and the center in the width direction of each product coil obtained as described above so that the total weight was 500 g, and the magnetic flux density B ₈ was measured by the Epstein test. The results obtained are also shown in Table 4.
From Table 4, it can be seen that the steel sheet to which any one or more of Ni, Sn, Sb, Cu, P, Mo, Nb, and Cr are added as an auxiliary inhibitor has a higher magnetic flux density than the steel sheet not added.

  Since the technique of the present invention can reduce the {001} <110> orientation, it can also be used as a method for improving ridging that occurs in a stainless steel plate or the like.

Claims (8)

A steel slab containing C: 0.01 to 0.10 mass%, Si: 2.0 to 4.5 mass%, and Mn: 0.01 to 0.5 mass% is hot-rolled to form a hot-rolled sheet. After sheet annealing, rolling at a reduction rate of 85% or more in one cold rolling, or rolling at a final cold rolling reduction rate of 80% or more in two or more cold rollings with intermediate annealing. In the method for producing a grain-oriented electrical steel sheet, which is a cold-rolled sheet having a final sheet thickness, and then subjected to primary recrystallization annealing and secondary recrystallization annealing,
A method for producing a grain ^- oriented electrical steel sheet, wherein a low strain rate cold rolling at a strain rate of 150 s ^-1 or less is applied at least one pass at a stage where the total rolling reduction in the cold rolling is 50% or less. The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the strain rate is 100 s ^-1 or less. The method for producing a grain-oriented electrical steel sheet according to claim 1 or 2, wherein the {001} <110> strength in the steel sheet structure after the low strain rate cold rolling is 10 or less. The method for producing a grain-oriented electrical steel sheet according to any one of claims 1 to 3, wherein rolling is performed at a strain rate of 400 s ^-1 or more after the total rolling reduction in the cold rolling exceeds 50%. In the said primary recrystallization annealing, the temperature increase rate between 500-700 degreeC shall be 50 degrees C / sec or more, The manufacturing method of the grain-oriented electrical steel sheet of any one of Claims 1-4 characterized by the above-mentioned. In addition to the above component composition, the steel slab further includes Al: 0.01 to 0.065 mass% and N: 0.005 to 0.012 mass%, and / or MnS / MnSe inhibitor component as an AlN inhibitor component. The grain-oriented electrical steel sheet according to any one of claims 1 to 5, wherein S: 0.005-0.03 mass% and / or Se: 0.005-0.03 mass% are contained. Production method. In the steel slab, in addition to the above component composition, Al, N, S and Se are further Al: 0.0100 mass% or less, N: 0.0050 mass% or less, S: 0.0050 mass% or less, and Se: 0.0050 mass. % Or less is contained, The manufacturing method of the grain-oriented electrical steel sheet of any one of Claims 1-5 characterized by the above-mentioned. In addition to the above component composition, the steel slab further includes Ni: 0.03-1.50 mass%, Sn: 0.01-1.50 mass%, Sb: 0.005-1.50 mass%, Cu: 0.00. 03-3.0 mass%, P: 0.03-0.50 mass%, Mo: 0.005-0.10 mass%, Nb: 0.0005-0.010 mass% and Cr: 0.03-1.50 mass% 1 or 2 types or more chosen from among these are contained, The manufacturing method of the grain-oriented electrical steel sheet of any one of Claims 1-7 characterized by the above-mentioned.

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