JPH0192318A - Manufacture of non-oriented magnetic steel sheet - Google Patents

Abstract

PURPOSE:To reduce the magnetic anisotropy of a magnetic steel sheet and also to reduce the uneven rotation of rotary equipment by hot-rolling a slab in which respective contents of C(Si+Al), and Mn are specified and applying cold rolling after pickling also to a cross direction at a specific draft. CONSTITUTION:A slab having a composition consisting of <=0.05% C, <=3.5% (Si+Al), <=1.5% Mn, and the balance Fe with inevitable impurities is cast. This slab is hot-rolled and pickled. Successively, the resulting steel strip 1 is rolled by means of longitudinal rolling mills 2, 3 and then passed through a looper 4 and fed to a cross rolling mill 5, where the strip 1 is subjected to cross rolling by plural passes. Subsequently, the above strip 1 is finished to the desired thickness by means of a longitudinal rolling mill 7 on the downstream side. At this time, transverse-direction draft is regulated to >=30% and also the total of longitudinal-direction draft and transverse-direction draft is regulated to 70-95%. Finish rolling is applied after the above cold rolling. By this method, a non-oriented magnetic steel sheet suitable for iron core material for rotary equipment and reduced in in-plane anisotropy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a non-oriented electrical steel sheet with low internal anisotropy, which is used as a core material for rotating equipment.

[Prior art] When using electromagnetic steel sheets as core materials for rotating equipment, internal anisotropy of magnetic properties may become a problem even in non-oriented electromagnetic steel sheets. Materials that exhibit non-directional magnetic properties are desired.

In the conventional manufacturing method of electrical steel sheets, rolling was performed only in the longitudinal direction of the belt, resulting in electrical steel sheets whose magnetic properties after annealing were biased in the rolling direction. Therefore,
When the iron core materials of rotating equipment are stacked in the same direction, it causes uneven rotation. For this reason, in order to prevent rotational unevenness in rotating equipment that requires particularly high precision, iron core materials are laminated one by one at different angles to improve the in-plane anisotropy (hereinafter referred to as magnetic) of the overall magnetic properties. (referred to as anisotropy).

[Problems to be Solved by the Invention] However, in this method, it was necessary to provide an extra step of stacking layers at different angles.

An object of the present invention is to manufacture a non-oriented electrical steel sheet that does not cause uneven rotation and has little magnetic anisotropy without providing such a process.

[Means for solving the problems] The present invention is a method for solving the above problems, and includes C
≦0.05%, (Si+Al) 53.5%, Mn≦1.
5%, the balance being Fe and unavoidable impurities, is subjected to normal hot rolling and pickled to form a hot rolled steel strip, and the reduction ratio in the width direction of the steel strip is 30% or more, and in the longitudinal direction and the width. This is a method for producing a non-oriented electrical steel sheet, which is characterized by performing cold rolling with a total reduction ratio of 70 to 95% in the direction and final annealing.

Also, c<o, oi% and (Si+Al)≧2.0
% steel billet, 600~1, before or after pickling.
It is preferable to perform annealing at 100°C.

Furthermore, in the case of a steel slab containing 2.01% Ca, it is preferable to perform decarburization annealing at 600 to 1.100°C either after or after pickling.

[Effect] The reason for limiting the composition of the steel slab in the present invention will be described below.

Since C has no effect on the magnetic properties of electromagnetic steel sheets, it is set to 0.
．． 0.5% or less.

Si and AQ are elements that are effective in increasing solid resistance and reducing iron loss, but when Si is added in large amounts, cold rollability deteriorates, and excessive addition of both S11A and Q reduces material cost. In order to increase (Si+A(11)), it is set to 3.5% or less.

Mn is also an effective element for reducing iron loss, but excessive addition is ineffective and increases material cost.
1.5% or less.

When hot rolling a steel billet having the above-mentioned chemical composition, the hot rolling is performed under commonly used conditions.

Pickling is necessary to prevent surface flaws from occurring due to scale peeling off and adhering to the work roll during cold rolling.

The chemical composition of the steel slab is C<0.0f% and (Si+A
l) In the case of 2.0%, surface defects called ridging are likely to occur after cold pressing. To prevent this ridging,
It is effective to perform annealing after hot rolling. In this case, the annealing may be continuous annealing or box annealing (either before or after pickling. Also, the temperature conditions for annealing are preferably 600 to 1,000 io.

On the other hand, when the chemical composition of the steel slab is 2.01% Ca, decarburization annealing may be performed as necessary after hot rolling to improve the magnetic properties. In this case, decarburization annealing is also continuous vl annealing,
Box annealing may be used, either before or after pickling.

Next, cold rolling in the width direction and longitudinal direction, which is the most important component of the present invention, will be explained.

Conventional electrical steel sheets are rolled only in the longitudinal direction of the steel strip during hot rolling and cold rolling, and as a result, the axis of easy magnetization of the crystal orientation is oriented in the longitudinal direction of the steel strip, so the magnetic flux density is lower than that of the steel strip. It has extremely large magnetic anisotropy in the longitudinal direction. This magnetic anisotropy also shows a similar tendency for iron loss values.

The present inventors have found through experiments that cold rolling in the width direction is effective in improving this magnetic anisotropy. That is, it has been found that the magnetic anisotropy is improved by making the crystal orientations, which are aligned in the longitudinal direction of the steel strip by hot rolling, random by performing width direction cold rolling.

In this case, the lower limit value was set to 30% since a sufficient effect of improving the magnetic anisotropy cannot be obtained unless the rolling reduction ratio of the width direction cold rolling is 30% or more.

In addition, the total reduction ratio of cold rolling in the width direction and lengthwise direction is 7
It was set as 0 to 95%. The reason for this is that if the reduction rate in cold rolling is less than 70%, the desired magnetic properties cannot be obtained;
This is because rolling becomes difficult if it exceeds this range.

Note that the conditions for finish annealing are not particularly limited, but (7
Burning may be performed at 00 to 1050° C0X (30 seconds to 1 minute).

[Example] FIG. 1 shows a schematic configuration diagram of a cold rolling mill for carrying out the present invention. In the figure, 1 is a steel strip, 2.3 and 7 are longitudinal rolling mills, 5 is a transverse rolling mill, 51 is a backup roll of the transverse rolling mill, 52 is a work roll of the transverse rolling mill, 4 and 6 are loopers provided on the inlet and outlet sides of the widthwise rolling mill.

With such a configuration, a procedure for rolling the steel strip 1 in the width direction and the longitudinal direction will be explained.

First, the steel strip 1 is rolled in the longitudinal direction by a longitudinal rolling mill 2.3, and then passed through a looper 4 and rolled in the width direction by a widthwise rolling mill 5 at a predetermined rolling reduction ratio.

The width direction rolling mill 5 moves along with the housing in the width direction from one side end of the steel strip 1, and when one pass of rolling is completed, the roll gap is opened and the steel strip 1 returns to its original position.
It moves downstream by the contact length with No. 2, and repeats the next pass of rolling in the width direction.

At this time, in order to prevent the steel strip 1 from having steep thickness differences between the buses, the work roll 52 is provided with a gently tapered shape at both ends as shown in FIG.

The rolling state of the steel strip 1 at this time is schematically shown in FIGS. 2 to 5.

FIG. 2 is a perspective view of the steel strip 1 being rolled in the width direction by the width direction rolling mill 5. FIG. 3 is a diagram showing the relationship between the longitudinal position of the steel strip and the plate thickness, and shows the relationship between the work roll 52 and the steel strip 1.
It is shown that the plate thickness decreases step by step by h for each contact length of each bus. Figures 4(a) to (e)
) is a top view of the steel strip 1 during rolling, and FIG.
), ■ is the state after one pass of rolling in the width direction, Figure 4 (b
), ■ is rolled at a position moved upstream by a length L in the longitudinal direction of the steel strip, and then moved downstream by the distance shown in Fig. 4 (
In this way, the part rolled in step 2 of a) is further rolled. As shown in FIG. Can be done.

When the predetermined multiple passes are completed in this way, the next multiple passes of rolling are repeated again to continue rolling in the width direction in sequence.

The steel strip 1 rolled in the width direction in this manner is further rolled in the longitudinal direction in a longitudinal rolling mill 7 on the downstream side, and is finished to a desired thickness.

Note that the storage length of the looper 4.6 may be any value that can ensure the moving length of the steel strip 1 in the aforementioned multiple passes of rolling.

Further, in the example shown in FIG. 1, the width direction rolling mill 5 is provided downstream of the longitudinal direction rolling mill 2.3, but the width direction rolling mill 5
may be provided on the most downstream side or on the most downstream side. However, if longitudinal plate thickness accuracy is required, it is preferable to provide it as far upstream as possible.

Next, a steel piece having the chemical composition shown in Sample No': A-H in Table 1 with thickness: 230 mm 1 - width: 500 mm 1 length: 4000 mm was heated to a temperature of 1'250°C1 finishing temperature: After hot rolling to a plate thickness of 2.3 mm under the conditions of 850°C and coiling temperature: 650''C, cold rolling to a plate thickness of 0.5 mm under the conditions shown in the same table, and then rolling at 850°C.
Finish annealing was performed for C×30 seconds. The results of measuring the magnetic flux density B2a in the longitudinal direction and the width direction for each sample are compared in the same table.

(Hereafter, blank space) Samples A-C have 2.0% (Si + Al) without grooves, and are cooled by changing the rolling reduction in the longitudinal direction and width direction without performing annealing before cold rolling as a countermeasure against ridging. This is an example of inter-rolling. In comparative examples where the rolling reduction ratio in the width direction is 0% and 20%, the magnetic flux density in the longitudinal direction (BL) and the magnetic flux density in the width direction (Be
) ratio (B.

/B,') is large, but in Example 1 where the rolling reduction in the width direction is 30% or more, BL/BC approaches 1, indicating that the magnetic anisotropy is improved.

Sample B has (Si+Al) of 2.0% or more, and the annealing before cold rolling as a countermeasure against ridging was performed by continuous annealing at 110%.
The sample was subjected to decarburization box annealing at 750°C for 5 hours as a countermeasure against ridging. In the examples in which the rolling reduction ratio is 30% or more, the magnetic anisotropy is improved compared to the comparative examples.

FIG. 6 is a graph showing the results of measuring the magnetic flux density at various angles in the longitudinal direction and the width direction after manufacturing Sample A in Table 1 under the conditions shown in the same table. In the figure,
The A line shows the magnetic anisotropy when the rolling reduction in the width direction is 0%, and similarly, the B line, E line, D line, and E line show the magnetic anisotropy when the rolling reduction in the width direction is 20% and 30%, respectively. , 50%, and 80% magnetic anisotropy.

As is clear from this figure, the widthwise pressure 'F-1 or 3
It can be seen that when it becomes 0% or more, the magnetic anisotropy is significantly improved.

[Effects of the Invention] According to the present invention, by performing cold rolling also in the width direction, the magnetic anisotropy of the electrical steel sheet can be significantly improved.
As a result, uneven rotation of the rotating equipment can be further reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the equipment configuration of a cold rolling mill in the width direction and longitudinal direction in the present invention, FIGS. 2 to 4 are diagrams showing a rolled deaf in the width direction, and FIG. FIG. 6 is a diagram showing the in-plane anisotropy of magnetic flux density. 1: Steel strip, 2.3.7: Longitudinal rolling mill, 4.6: Looper, 5: Width rolling mill. Longitudinal magnetic flux density BL (B25)

Claims (3)

[Claims] (1) C≦0.05%, (Si+Al)≦3.5%, M
A steel billet consisting of n≦1.5%, the balance being Fe and unavoidable impurities is subjected to normal hot rolling and pickled as a hot-rolled steel strip, and the reduction ratio in the width direction of the steel strip is 30% or more, and Cold rolling is performed with a total reduction ratio of 70 to 95% in the longitudinal direction and width direction,
A method for manufacturing a non-oriented electrical steel sheet, which comprises final annealing. (2) C<0.01% and (Si+Al)≧2.0
% steel billet, 600~1, before or after pickling.
The method for manufacturing a non-oriented electrical steel sheet according to claim 1, characterized in that annealing is performed at 100°C. (3) In the case of steel slabs with C≧0.01%, decarburization annealing is performed at 600 to 1,100°C before or after pickling, as set forth in claim 1. A method for manufacturing non-oriented electrical steel sheets.