JPS6357724A - Manufacture of grain-oriented silicon steel sheet containing no linear fine grain - Google Patents

Abstract

PURPOSE:To perfectly prevent the formation of linear fine grains by annealing a hot coil contg. specified amounts of Si, C and Fe at a high temp. in a prescribed temp. range. CONSTITUTION:A hot coil consisting of 2-4wt% Si, <=0.085wt% C and the balance Fe with an inhibitor is manufactured. The hot coil is cold rolled to the final thickness and held at a temp. between a temp. T at which a secondary recrystallization annealing region is held and a temp. at which a forsterite film is formed. The temp. T is represented by the formula, wherein High (A, B, C...) is the highest one among A, B, C...TA(LE)=High(TA1(LE), TA2(LE)...TAn(LE)), TAn(LE) is the n-th secondary recrystallization temp. in the lateral direction of the coil at the tip part of the coil, TA(TE)=High(TA1(TE), TA2(TE)...TAn(TE)) and TAn(TE) is the n-th secondary recrystallization temp. in the lateral direction of the coil at the tip part of the coil.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a steel plate in which the crystals constituting the steel plate are (110)<001).
The present invention relates to a method for manufacturing a unidirectional silicon steel sheet that has a certain orientation and is easily magnetized in the rolling direction, and particularly relates to a method for manufacturing a product without linear fine grains.

[Conventional technology]

If linear fine grains are generated in a unidirectional silicon steel sheet, the electromagnetic properties of that part, especially iron loss, will deteriorate, so it is desirable to prevent these linear fine grains.

As a conventional technique, Japanese Patent Publication No. 50-37009 and Japanese Patent Publication No. 60-37172 disclose that heating and rolling are carried out in advance before the hot rolling process, and that crystal coarsening occurs when the slab is heated to a high temperature in the subsequent hot rolling process. In the process of hot rolling a silicon steel slab after heating it to a high temperature, a technology for preventing this is disclosed.
A method for producing a unidirectional silicon steel sheet, characterized by performing recrystallization high-reduction rolling at least once at a rolling reduction of 0% or less, and preventing linear fine grains in the product by subsequently forming the product in a normal process. is disclosed.

[Problem that the invention seeks to solve]

However, the technique described in L has the following drawbacks.

(1) Although it is necessary to perform controlled recrystallization rolling in the hot rolling process, it takes time and effort to search for the appropriate temperature range using an actual rolling mill.

(2) The speed of rolling mills has become faster and faster in recent years, making it difficult to secure time for dynamic recrystallization.

From this point of view, the present inventor researched the treatment of slabs in the cold rolling process rather than the hot rolling process, and by adopting the processing conditions, it was possible to manufacture products without the above-mentioned defects. Successful.

An object of the present invention is to provide a method in the cold rolling process of unidirectional silicon steel sheets that does not reduce the productivity of hot rolling and easily prevents the generation of linear fine grains in the finished product. be.

[Means for solving problems]

The present invention includes (a) Si: 2 to 4% by weight, C: 0.085% by weight
(b) This hot coil is cold-rolled to a final thickness, (C) The coil is then folded in a high-temperature annealing process. Production of a linear, grain-free unidirectional silicon steel sheet, which is maintained at a temperature below the stellite film formation temperature and in the secondary recrystallization annealing region of a temperature tool expressed by the following formula (1). I-no is used as a technical means.

T = )light (TA (+-E), TA
(TE) )・・・・・・(1) However, the symbol old gh (A, B, C,...) is A, B, C2...
・Indicates the highest temperature.

TA(LE)=High(TA1(LE)
.

TA2 (LE), ..., TA n (LE))
TAn(tE): n-th secondary recrystallization temperature in the width direction at the tip of the coil TA(TE) = High (TA l(TE)
.

TA2 (TE) , -, TAn (TE))T
An(v E): Width direction n at the tip of the coil
2nd secondary recrystallization temperature T: This is the secondary recrystallization annealing region holding temperature.

[Effect]

The present invention will be explained in detail below.

The present invention aims at making the final high-temperature annealing temperature equal to or higher than the secondary recrystallization temperature of the material in the continuous casting process and the cold rolling process following the hot rolling process in the production of grain-oriented silicon steel sheets. As a result, it is possible to stably produce a complete product of secondary recrystallization without linear fine grains.

The silicon steel hot coil targeted by the present invention has Si: 2 to 4.
Weight %, C: 0.085% or less, and inhibitor components such as Mn, S, Se.

It contains A, sb, etc. as appropriate, and the remainder consists of iron and mixed impurity elements.

The reason for limiting the above-mentioned components is that when Si exceeds 4 hands=% by weight, cold rolling becomes difficult, which is not preferable. If it is less than 2% by weight, it will be disadvantageous in terms of magnetic properties.

Therefore, the amount should be 2 to 4% by weight.

When C exceeds 0.085% by weight, it becomes difficult to perform complete decarburization annealing, which is not preferable. The starting material of the present invention is a hot-rolled plate obtained by a steel manufacturing method, a continuous casting method, or a hot rolling method, which are already known techniques. This hot rolled sheet usually has 1
The final thickness is obtained by cold rolling and intermediate annealing more than once. After cold rolling, the steel sheet is subjected to decarburization annealing and final annealing after coating MgO on the surface of the steel sheet. The flattening annealing after the final annealing may be performed using a known method.

In the above steps, the feature of the present invention lies in the final annealing step.

As shown in FIG. 1, this final annealing consists of a secondary crystal annealing region A and a purification annealing region B at a higher temperature.

In the secondary crystal region A, the steel plate is (110) (001)
The annealing temperature T plays an extremely important role in this process because it is covered with oriented secondary recrystallized grains.The present invention determines this annealing temperature T. It is possible to stably produce grain-free unidirectional silicon steel sheets.

Now, the inventors investigated the secondary recrystallization behavior of the coil after decarburization annealing to reach the final plate thickness in the longitudinal and width directions of the coil. The results are schematically shown in FIGS. 2 and 3. Fig. 2 shows how the secondary recrystallization temperature (hereinafter referred to as TA) changes in each steel plate section that is subdivided in the width direction of the coil. TA changes randomly and varies. Figure 3 shows the steel plate with TA shown in Figure 2 at TAmax or TAI! This figure shows the generation rate of linear fine grains when actually annealed at in.

When a steel plate is annealed at a temperature of TAain or higher,
The fine particle generation rate is 100%, whereas TAIilai
It can be seen that in those annealed at a temperature higher than or equal to that, no linear fine grains were generated at all.

FIG. 4 shows the change in secondary recrystallization temperature in the longitudinal direction of the coil. TA changes linearly from the tip (LE), middle (M), and tail (TE), but the absolute value is random.

Figure 5 shows the steel plate with TA shown in Figure 4, TAll, 6
, is the change in linear fine grain ratio when actually annealed with TA ff1in.

When annealing at a temperature of TA win or lower, the percentage of linear fine grains is 100%, whereas when annealing at a temperature of TAIIlaI or higher, the linear fine grains completely disappear.
A uniform secondary 1'T crystal structure is obtained. In this case, of course, the temperature must be below the forsterite film forming temperature.

〔Example〕

Example I C: 0.05% by weight Si ・3.3% by weight Se: 0.040 heavy stitching% The final plate thickness of the hot coil was 0.23 mm.

Decarburization annealing was performed at 840°C, and the secondary recrystallization temperature in the width direction and longitudinal direction was measured, and the results were as follows.

TA (LE) = High (TAI-1(LE)
) ) = 840TA (TE) = High
h (TAn(vE)) = 8 5
1T=High(TA(LE), TA(TE))=85
1 Then, final box annealing was carried out at 851'0.
The linear fine grain ratio was O.

Example 2 A hot coil containing C: 0.06% by weight, Si: 3.1% by weight, Text A: 0.03% by weight was manufactured and cold rolled once to give a final plate thickness of 0.20 mm. Decarburization annealing was performed at 840°C, and the secondary recrystallization temperatures in the width direction and longitudinal direction were measured, and the results were as follows6 TA (LE) = 920 TA (TE) = 891 T = 9 2 0 Therefore, the comparison was made. When the final box type annealing was carried out at 920°C, the linear fine grain ratio was O.

[Effect of ``Bun 19'']! Regardless of Af14 conditions and hot rolling conditions, by selecting the final annealing temperature, the generation rate of linear fine grains can be completely eliminated.

[Brief explanation of drawings]

Figure 1 is a graph showing the heat pattern of final annealing, Figure 2 is a graph showing the heat pattern of final annealing.
The figure is a graph showing changes in secondary recrystallization temperature in the width direction.
The figure is a graph showing the relationship between linear fine grain generation rate and annealing temperature, Figure 4 is a graph showing changes in secondary recrystallization temperature in the length direction,
FIG. 5 is a graph showing the relationship between linear fine grain generation rate and annealing temperature.

Claims (1)

[Claims] 1. A hot coil containing Si: 2 to 4% by weight, C: 0.085% by weight or less, and an inhibitor component, with the remainder being Fe and unavoidable impurity elements is produced, and the hot coil is cold heated. The final plate thickness is achieved by rolling, and then in a high-temperature annealing process at a temperature below the forsterite film formation temperature,
A method for producing a unidirectional silicon steel sheet without linear fine grains, characterized in that the temperature is maintained in a secondary recrystallization annealing region at a temperature equal to or higher than the temperature expressed by the following formula (1). T=High(T_A(LE), T_A(TE))...
...(1) However, the symbol High (A, B, C, ...) is A, B, C, ...
...indicates the highest temperature. T_A(LE)=High(T_A_1(LE), T_
A_2(LE), ..., T_A_n(LE))T_A
_n(LE): n-th secondary recrystallization temperature in the width direction at the tip of the coil T_A(TE)=High(T_A_1(TE), T_
A_2(TE),...,T_A_n(TE))T_A
_n(TE): Secondary recrystallization temperature at the nth width direction at the tip of the coil T: Secondary recrystallization annealing region holding temperature.