JPS613838A - Manufacture of electromagnetic steel sheet having small anisotropy - Google Patents

Abstract

PURPOSE:To manufacture an electromagnetic steel sheet having small anisotropy by cold rolling a hot rolled steel strip contg. specified amounts of C, Si, Mn and Al twice under specified conditions while carrying out annealing process between the cold rolling stages and by subjecting the cold rolled steel sheet to finish annealing. CONSTITUTION:The hot rolled steel strip contg., by weight, <0.08% C, <2% Si, 0.05-1% Mn and <1% Al is cold rolled twice while carrying out process annearling between the cold rolling stages, and the cold rolled steel sheet is subjected to finish annealing to manufacture an electromagnetic steel sheet. At this time, the steel sheet having 30-70% rate of recrystallization after the annealing process is subjected to secondary cold rolling to the final thickness at 6-15% draft and finish annealing at the A3 transformation point or below.

Description

[Detailed Description of the Invention] (Technical Field) This specification relates to the method for manufacturing non-oriented electrical steel sheets.
The technical content described in this book is to propose a method for manufacturing electrical steel sheets with low anisotropy, which are particularly advantageous as core materials for small motors, etc.

(Background technology) In recent years, there has been a strong demand for higher efficiency of small motors from the viewpoint of energy conservation. In order to make the motor highly efficient, k′ requires a material with low iron loss and high magnetic flux density, but as a material for rotating equipment such as small motors,
° It is particularly important that the anisotropy is small.

(Prior art and its problems) The ideal crystal orientation is so-called in-plane non-direction, in which the ('i o o ) plane is parallel to the plate surface, and several manufacturing methods have been proposed.

For example, there is a method of first annealing after strong cold rolling, as typified by Japanese Patent Application Laid-open No. 1985-82722, and
As described in No. 66.18 and Japanese Patent Publication No. 41-7929, there is a method of developing one (100) plane on the plate surface by warm rolling, final rolling of the (100) method, and strong cold rolling. generally well known.

However, the reality is that all of the above methods require a long time for final annealing, and the production cost is inevitably high due to the fc.

(Object of the invention) This invention was made against the background of the above circumstances (
10L) The purpose is to provide a method for manufacturing electrical steel sheets with a developed <O'VW> texture, low anisotropy, and excellent magnetic properties on an industrial scale at low cost. be.

In order to achieve this objective, the inventors conducted extensive experiments and studies, and found that when cold rolling is performed twice with intermediate annealing in between, recrystallization after intermediate annealing can be reduced by 80% to 70%. An electrical steel sheet having a (100) <OVW> orientation can be manufactured by controlling the specific conditions of and at the same time lightly reducing the rolling reduction l in the secondary cold rolling after intermediate annealing within the range of 6% to 15%. Moreover, in this case, the present invention was completed based on the new finding that continuous furnace annealing can be applied to the final annealing.

This invention provides a; o, oao weight% or less, Sl; 2;
．． 0% by weight or less, Mn; 0.05-1.0% by weight,
In a method for manufacturing a magnetic steel sheet, a hot rolled steel strip containing 1.0% by weight or less of Al is subjected to two cold rollings with intermediate annealing in between, and then finish annealing, in which recrystallization after intermediate annealing is performed. A steel plate with a roughness of 80 to 70% is subjected to secondary cold rolling at a reduction height of 6% to 15% to achieve the final plate thickness, and then finish annealed at a temperature below the A8 transformation point. (2) A method for producing an anisotropic electrical steel sheet.

The development history of the method of the present invention will be explained below based on experimental data.

GO, 00.8% by weight (hereinafter simply 1 for component content).

Shown in %. ) A hot rolled steel strip having a thickness of 2.8fi and having a composition consisting essentially of Si 0.85%, MnO 1% and A7IO 002% balance Fe was rolled qw, 8% to 77.1%.
The intermediate plate thickness is 0.6j2 by performing primary cold rolling within the range of %.
5 m to □0.526 m, and then placed in a dry nitrogen gas atmosphere2. .

Intermediate annealing was carried out for 2 minutes at various temperatures within the range of 6oO''C to 750''C in a continuous air furnace.

Secondary cold rolling was then carried out on various reduction wheels ranging from 5'% to 20%, each to a final thickness of 0.50 mm.

After that, these cold-rolled sheets were subjected to s in a continuous furnace in a nitrogen gas atmosphere.
Finish annealing was performed for 2 minutes at a temperature of 0.05 m to obtain an electrical steel sheet product.

A ring-shaped sample (hereinafter referred to as a ring) with an outer diameter of loam and an inner diameter of 50 m was punched out from the obtained product plate, 51 sheets each were laminated, and each laminate was subjected to primary and secondary windings of 200 turns. Magnetic measurements were taken to determine the iron agent W15150 and the magnetic flux density B. I looked into it.

In the above-mentioned process, the crystal structure of the steel plate after intermediate annealing was observed using an optical microscope, and the recrystallization chamber 1 was examined.

In addition, the texture of the steel sheet was investigated after magnetic measurements. The results of magnetic properties are shown in Table 1.

Table-1 Upper row is W 15150 (WA9) Lower row is B11 (T) As shown in Table-1, magnetic flux density B50 by ring sample
(hereinafter referred to as ring B5o) strongly depends on the intermediate annealing temperature and the secondary cold rolling reduction ratio, and the intermediate annealing temperature is 650°C.
~700'C1 secondary cold rolling reduction -1°7%~1
It was clear that the improvement was 1 at 5%.

On the other hand, the iron loss of the ring sample W15750 (hereinafter referred to as ring W1
5/60) decreases as the intermediate annealing temperature increases.

The recrystallization temperature of steel materials varies depending on the chemical composition and processing history of the steel plate. Therefore, even if the annealing temperature is the same, if the composition of the material, the rolling reduction before annealing, and the annealing time change, the structure after annealing will also change. .

And also after intermediate annealing? It is thought that the structure affects the 1.゛recrystallization texture during final annealing.

Therefore, the inventors investigated the recrystallization rate of the steel sheet after intermediate annealing as described above, and investigated the relationship between the recrystallization rate, the secondary cold rolling reduction rate, and the ring B5o and ring Wls/lio of the product. The results are shown in Figure 1.

From Fig. 1, the ring Bso value largely depends on the recrystallization rate after intermediate annealing and the secondary cold rolling reduction ratio, and the recrystallization rate is ao =
In the range of 7u%, and the secondary cold rolling reduction rate is 7% to 1
It has been found that a high B5o value can be obtained at 5%.

Next, from among the conditions shown in Table 1, select (A) (B) as shown below.
l (Final finish annealed plate (product plate) with an analysis thickness of 0.5OR that was subjected to intermediate annealing and secondary cold rolling under 8 conditions of C1
The texture of and the corresponding microscopic structure after intermediate annealing are shown in Fig. 2 with subscripts 1, 2, and 8 as fAj (9
A corresponding diagram is shown in 1fil.

(A1; Intermediate annealing was performed at 600° C. for z minutes, and the secondary cold rolling reduction was 15%. In this case, the crystal thickness after intermediate annealing was 10%.

(Comparative method) (B): Intermediate annealing was performed at 6° 15° C. for 2 minutes ffL, and the secondary cold rolling reduction was 15%. In this case, recrystallization after intermediate annealing was 50%.

(Inventive method) (C); Intermediate annealing was performed for 725'CXZ minutes, and the secondary cold rolling reduction was 115% l. In the case of 3°, the recrystallization rate after intermediate annealing was 90%.

(Comparative method) Figure 2 (The texture of AI is such that the intermediate annealing temperature is low and the recrystallization rate is 10%. In this case, the main orientation is (llll) [112]. It is clear from the figure that

On the other hand, in FIG. 2 (C1), the intermediate annealing temperature is too high and the subsequent recrystallization rate is 90%, and in this case, the (110) and (211) orientations are strongly concentrated.

In contrast, in Figure 2 (Bl is the intermediate annealing treatment according to the method of the present invention, with 50% recrystallization, and (100) it is clear that the texture is developed. be.

In the (100) plane, the axis of easy magnetization (100> exists the most, and there is no difficulty in magnetization and does not include the 111>). The sample has excellent magnetic tactility d. The proportion of the recrystallized structure after intermediate annealing is adjusted to a range of 80% to 70% at 5K as described above, and then the secondary cold rolling is carried out at a reduction rate of 6. It has been found that by applying light rolling in the range of % to 15%, a (loo)<ovw> texture can be formed by -1° even in short-time finish annealing such as continuous furnace annealing.

Next, the reasons for limiting the ingredients of the materials used in the method of this invention will be described.

Since C is a harmful element in terms of magnetic properties and aging deterioration, it is preferable that the content is as low as possible. o
, oao% or less. However, in the method of this invention, since decarburization annealing is not usually performed, it is preferable that 0 be low from the initial stage.

Sl is an effective element for reducing iron loss, but on the other hand, 6
Since it lowers the fi east density, it is set to 2.0% or less in order to ensure a high 1/1 magnetic flux density.

In is added to suppress hot brittleness, but 0.0
If it is less than 5%, the effect cannot be obtained, while if it exceeds 1.0%, the magnetic properties will deteriorate, so In is 0.05 to 1.0%.
The range of

Al is an element that has the effect of developing a (100) texture and contributes to improving magnetic properties, but if it exceeds 1%, the rollability becomes arbitrary, so it was set to 1% or less.

Next, a series of manufacturing steps according to the method of the invention will be explained.

First, a slab having the above composition is obtained by a continuous casting method or an ingot-blowing rolling method.

Then, it is hot rolled by a known method to a thickness of 2.0 to 8.0 mm. These dimensions are not particularly limiting.

Next, the hot-rolled plate is subjected to primary cold rolling to give a 0.58-0.69-
The thickness of the plate is set to about 100,000 yen, and intermediate annealing is performed. Under these intermediate annealing conditions, the recrystallization rate of the steel sheet before the subsequent secondary cold rolling is 80.
The annealing temperature and time are selected so that the annealing temperature is ~70%. In the case of the steel composition used in this invention, such a structure in which rolling deformed grains and recrystallized grains are mixed is usually formed at a temperature of 60°C.
The temperature is 0 to 700°C and the time is about 1 to 8 minutes.

As mentioned above, the reason why the recrystallization rate after intermediate annealing is limited to 80 to 70% is that as mentioned above, when the recrystallization rate is less than 80%, the rolled structure is too strong, so it is difficult to roll in the subsequent secondary cold rolling. The structure is further strengthened and the strain is not released sufficiently during the subsequent final annealing, resulting in delayed grain growth (111)
The texture is prioritized 2...° and the magnetic properties deteriorate, while the recrystallization rate after intermediate annealing is 1? If it exceeds θ%, the (ito) texture will develop due to the final annealing after the secondary cold rolling and the anisotropy will become strong, making it unsuitable for use as rotating equipment such as small motors.

For the above reasons, the recrystallization rate after intermediate annealing is 80 to 70.
%.

After the intermediate annealing, the final plate thickness is obtained by performing a secondary pressure value. The rolling reduction in this secondary cold rolling is within the range of 6 to 15%, and is a light reduction of the so-called skin pass level 11). If the reduction ratio is less than 6%, sufficient strain will not be introduced, resulting in insufficient grain growth during final annealing.On the other hand, if the reduction ratio exceeds 15%, the anisotropy will become strong, making it unsuitable as a material for rotating equipment. Become something.

Next, final annealing is performed, but this final annealing may be performed at a temperature of A8 point or lower, and the lower limit is not limited to %.

As mentioned above, this final annealing is done in an extremely short time (100)
Since <OVW> texture can be formed, continuous furnace annealing can be applied.

However, on the other hand, this invention also works as a semi-processed electrical steel sheet.
Since it is applicable, strain relief annealing may be performed at a temperature of about 750° C. for 1 to 2 hours after punching.

In this case, the above-mentioned final annealing may be omitted.

In fact, by performing stress relief annealing, the ring Wls750 is significantly improved without deteriorating the ring Bso.

'The electromagnetic steel sheet obtained by further 5k has a thickness of (10
0) (100)<OVW with parallel planes and random axis orientation
As described above, it can be suitably used as an iron core material for high-efficiency motors.

(Example) Next, the present invention will be explained with reference to embodiments.

00.01Q%, 810.82%, Mn0.82%, p
o,ots.

A hot-rolled plate with a thickness of 2.6 cm consisting of KAMO, SO, 008%, and AJ O, 001% was pickled and 0-6N
It was first cold rolled to b tm *0.59 m and 0.58 soz.

Next, the rolled plate is degreased, dried, and placed in a continuous furnace in a nitrogen gas atmosphere to 0.5211+1 and 0.5211+1. H5 parrot rolled plate is 6
At a temperature of 00°C, a rolled plate with a thickness of 0.59 m is 580°C.
Intermediate annealing was performed at various temperature ranges of ~710"C for 1 minute each.

A second round of cold rolling was carried out and the product was finished to 0.60ag.

After degreasing, the rolled plate was continuously annealed at 850°C for 2 minutes in a nitrogen gas atmosphere -□ air.

, these annealed materials were laminated with five punched sheets each on a ring sample with an outer diameter of 1'00 m5 and an inner diameter of 50 mm, and a primary and secondary winding of 200 turns was applied to each laminate.
50', W15150 iron loss and B5o magnetic flux density were measured for magnetic tactility, and the results shown in Table 2 were obtained.

Table-2 (Effect of the invention) The invention significantly improves B2O.

Brief description of the surface surface Figure 1 shows recrystallized groups and magnetic bone properties of ring sample 1 after intermediate annealing, B. (T), W 11115G (W/
iw) is a diagram showing the relationship between the two in terms of secondary cold rolling and blockage, respectively.

The z-diagram (Al, (8), (0) is the ('5oo) pole figure of the product after final annealing, the X-ray photograph sketch, and the metallurgical microscope Mitsuma showing the crystal structure after intermediate annealing, respectively.
(A) and (C) are those obtained by Comparative Method 1, respectively, and (Bl is obtained by the method of the present invention).

Special-age applicant Kawasaki Steel Corporation (A-f) (B-/) (A-
2) (B-2) (C-fn (C-2)

Claims (1)

[Claims] 1. Hot rolled steel containing C; 0.080% by weight or less Si; 2.0% by weight or less Mn; 0.05 to 1.0% by weight and Al; 1.0% by weight or less In a manufacturing method for electrical steel sheets in which the strip is cold rolled twice with intermediate annealing in between, and then final annealed, a steel sheet with a recrystallization rate of 80 to 70% after intermediate annealing is rolled at a rolling reduction of 6.
% to 15% to achieve the final plate thickness, and then final annealing at a temperature below the A_3 transformation point. .