JPS61264131A - Manufacture of electrical steel sheet having small magnetic anisotropy and superior characteristic in weak magnetic field - Google Patents

Abstract

PURPOSE:To manufacture an electrical steel sheet having small magnetic anisotropy and superior characteristics in a weak magnetic field by subjecting a hot rolled steel sheet contg. specified amounts of C and Si to primary cold rolling, process annealing and secondary cold rolling under specified conditions. CONSTITUTION:A hot rolled steel sheet contg. <0.02wt% C and 0.1-4.5wt% Si is subjected to primary cold rolling, process annealing and secondary cold rolling to manufacture an electrical steel sheet. At this time, the secondary cold rolling is carried out at 1-15% draft and >=500m/min rolling rate. The resulting steel sheet is subjected to finish annealing as required.

Description

[Detailed Description of the Invention] <Industrial Application Fields> This invention has small magnetic anisotropy and excellent low magnetic field characteristics, making it suitable for use as an iron core material for small control motors, etc. ! The present invention relates to an advantageous manufacturing method for electrical steel sheets.

(Conventional technology) Rotating machines range from large rotating machines for water wheels and turbines to D
There are various types of motors ranging from C motors to small control motors such as stepping motors, and correspondingly, the properties required of the material used as the iron core of rotating machines differ depending on the intended use. come. For example, in the case of a large rotating machine, high magnetic flux density and low core loss are required, so high-grade non-oriented ffiff1m plate or grain-oriented electrical steel plate is used as the iron core material.

On the other hand, for small electric motors such as household electrical equipment, low-grade non-oriented electrical steel sheets are generally used because it is desired to have high magnetic flux density and low price even if iron loss increases to some extent.

By the way, among such small electric motors, the iron cores of small control motors, such as DC motors and stepping motors, are different from general small electric motors and are used in low magnetic field regions, so the iron core materials are suitable for excitation in low magnetic fields. It is required that the characteristics, namely magnetic permeability, be excellent.

With the development of OA and FA in recent years, the demand for small control motors has increased dramatically, and at the same time, the demand for electrical steel sheets with excellent low magnetic field properties has also increased.

(Problems to be Solved by the Invention) However, until now, process factors that affect the low magnetic field characteristics of electrical steel sheets have not been clarified.

This invention was developed in view of the above circumstances, and aims to propose a method for manufacturing an electrical steel sheet that has small magnetic anisotropy and excellent excitation characteristics in low magnetic fields, that is, magnetic permeability. It is something.

<Means for Solving the Problems> As a result of intensive experiments and studies to achieve the above object, the inventors have developed a method for manufacturing electrical steel sheets that involves cold rolling twice with intermediate annealing in between. In particular, the rolling reduction and rolling speed during two-high rolling after intermediate annealing have a large effect on the texture of the steel plate after subsequent annealing, and it is necessary to carry out such secondary rolling with an appropriate rolling reduction and rolling speed. We obtained the new finding that excellent low-field properties and good magnetic anisotropy can be obtained by rolling at a high rolling speed.

This type of electrical steel sheet is a so-called full-process product that is manufactured by cold rolling followed by short-term final annealing so that it already has the final magnetic properties when shipped from the steelworks. When shipped from a steelworks, it is an intermediate product that has been cold-rolled, but it is not until the customer performs processing such as punching and annealing to remove strain that it becomes a so-called semi-product, which exhibits its final magnetic properties. Although there are process products, we have also found that the above method can be applied to the production of both of these products.

This invention is based on the above knowledge.

That is, this invention provides C: 0.02wt%<1. Below) (indicated in %) and Si: 0,
In producing an electrical steel sheet by subjecting a hot rolled steel sheet having a composition containing 1 to 4.5 wt% to cold rolling twice with intermediate annealing in between, and sometimes further followed by final annealing,
The secondary interstage rolling after the above intermediate annealing is performed at a rolling reduction ratio of 1 to 15.
% and rolling speed: 500 m/min or more.This is a method for producing semi-processed or full-processed electrical steel sheets having small magnetic anisotropy and excellent low magnetic field properties.

First, the experimental results that led to this invention will be explained.

A continuous cast slab having a composition containing CO, 006% and Si 0.58% is made into a hot-rolled steel plate with a thickness of 2 and a button m by known hot rolling, and this hot-rolled steel plate is subjected to a rolling reduction of 73 to 78%. The intermediate plate thickness is 0.62~o, si
After closing the mm, it was heated to 8°C in a nitrogen gas atmosphere.

Intermediate annealing was performed at ℃ for 2 minutes. Next, rolling was carried out between two degrees at various rolling reductions in the range of 0.3 to 20%, and each
The final plate thickness was 0nun. In addition, during this secondary interstory rolling, the rolling speed was also varied in the range of 10 to 2500 m/min.

After that, each of these cold-rolled sheets was heated at 800°C in a nitrogen gas atmosphere.
A short time finish annealing was performed for 2 minutes to produce an electrical steel sheet product.

FIG. 1 shows the relationship between the average B1 value of each steel sheet obtained in this way in the rolling direction and the direction perpendicular thereto, and the rolling reduction and rolling speed in secondary interstory rolling. The Si value here is the magnetic flux density at a magnetizing force of 100 A/m,
The excitation characteristics at low magnetic fields were taken as representative values.

From Figure 1, the B1 value largely depends on the rolling reduction rate and rolling speed in the secondary interstory rolling, especially the secondary cold rolling reduction rate of 1 to 15.
%, and it was revealed that a high B1 value of 0.7 T or more was exhibited when the rolling speed was 500111/min or more.

Next, FIGS. 2a to 2f show examples of torque curves showing changes in texture due to differences in secondary cold rolling reduction ratio and rolling speed, respectively. The torque curve here indicates the magnetic anisotropy of the material, and the torque intensity becomes stronger in a direction closer to the axis of easy magnetization.

From the figure, the texture of the steel plate changes greatly depending on the difference in rolling reduction and rolling speed, and the weak (111) plane is predominant in the steel plate with a high B1 value (c in the figure), while the (111) plane is dominant. Steel plates with low B1 values (a, d, e, f in the same figure) have (1
10) There was a tendency for the surface to become stronger. Therefore, a steel plate with a high B1 value has a nearly non-directional structure in the plane, whereas a steel plate with a low B1 value has strong anisotropy and has excellent properties in the rolling direction but poor properties in the perpendicular direction. It is considered that the B1 value, which is the average value in the direction, becomes low.

Needless to say, a material with low anisotropy is suitable as a material for a rotating machine.From the above results, it is possible to improve magnetic It has been found that this method is extremely effective in producing materials that have low magnetic anisotropy and excellent excitation characteristics in low magnetic fields, and are particularly suitable for small control motors.

As a result of further research based on these basic data, the inventors were able to create an electromagnetic material with low magnetic anisotropy and excellent excitation characteristics in low magnetic fields by regulating the manufacturing conditions as shown below. It was confirmed that steel plates can be manufactured.

First, we will discuss the reason why the material components were limited to the above range.

C: 0.02% or less C has an adverse effect on magnetic properties and magnetic aging, so its content was limited to 0.02% or less.

Si: 0.1 to 4.5% Sl is a preferable element in terms of magnetic properties, but from the viewpoint of this property and punching workability, the lower limit is set to 0.1%, while 4.
If added in excess of 5%, it becomes brittle and reduces rollability, so the upper limit was set at 4.5%.

Regarding other components, AI may be added in an amount up to 2% for the purpose of improving iron loss by increasing specific resistance. In addition, since impurities such as O, N, and S are harmful to magnetic properties, it is desirable to reduce them as much as possible.
In particular, it is preferable that O be 1100 pp or less.

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

First, a slab having the above composition is produced by a continuous casting method or an ingot-blowing rolling method. Next, a hot-rolled plate having a thickness of about 2.0 to 3.0 mm is finished by known hot rolling. However, it goes without saying that the plate thickness is not limited to this dimension. Next, the hot-rolled sheet is determined by the thickness of the hot-rolled sheet, the product thickness, and 2.
After primary cold rolling is performed at a reduction rate that takes into account the reduction rate of Otsu rolling, intermediate annealing is performed at a temperature of approximately 700 to 100°C.

Next, two-dimensional rolling is carried out, and as mentioned above, during this secondary rolling, the reduction rate is 1 to 15% and the material is rolled at a rolling reduction rate of 1 to 15% so that a texture with small magnetic anisotropy is obtained during subsequent annealing. Rolling speed 500 m/min or more, preferably 500 to 25
It is important to set the speed to 00m/min.

The thus obtained cold-rolled steel sheet is further coated with 700 to 1100
By performing annealing at a temperature of about m, a steel plate with small magnetic anisotropy and excellent low magnetic field properties can be obtained. This annealing may be either short-time finish annealing performed following cold rolling, or strain relief annealing performed after cold rolling and then punching.

(Function) The reason why magnetic anisotropy and low magnetic field properties are significantly improved by performing two-way rolling at a low rolling reduction and high rolling speed according to the present invention has not yet been clearly elucidated. However, it is thought that this is due to the (111) plane becoming dominant in the texture of the rolled material.

(Example) Example 1 A continuously cast slab containing C: 0.006% and Si: 0.55% is made into a hot rolled steel plate with a thickness of 2.3 mm by known hot rolling, and this hot rolled steel plate is made into a 2.3 mm thick hot rolled steel plate. The intermediate plate thickness is 0.62 to 0.5/am by performing primary cold rolling at a rolling reduction rate of 78%.
After that, intermediate annealing was performed at 800° C. for 2 minutes in a nitrogen gas atmosphere. Then, as shown in Table 1, 0.3~
Performing secondary rolling at various reduction rates in the range of 20%,
Each had a final plate thickness of 0.50 mm. In addition, when rolling between these two majors, the rolling speed was also 10°500, 250°.
The speed was varied in three ways: 0 m/min.

Width 0n+m, length 2 from the cold-rolled steel plate obtained in this way
Eight specimens of 80n+m were taken from each of the vertical and horizontal grains and subjected to strain relief annealing at 750° C. for 2 hours in a nitrogen gas atmosphere, and then subjected to Epstein measurement.

Table 1 shows the average Sl values in the rolling direction and the direction perpendicular to it.
The relationship between the next cold rolling reduction ratio and rolling speed is shown.

Table 1 As is clear from the table, secondary cold rolling reduction ratio: 1 to 1
5% and a rolling speed of 500 m/min or more, a high B1 value of 0.7 T or more was obtained.

Although only the B1 value is shown in the same table, as is clear from the results shown in Figures 1 and 2 above, those with high Bi values also have extremely small magnetic anisotropy. It's confirmed.

119L Continuously cast slab (A'') containing C: 0.006%, Si: 0.58%, C: 0.004%, Si
: Continuously cast slabs (B) and C containing 1.85%:
Continuously cast slab containing 0.007%, Sl: 3.20% (
C) to a thickness of 2.3 m by known hot rolling.
m hot-rolled steel sheets, and these hot-rolled steel sheets were subjected to 1 water cold rolling at a rolling reduction ratio of 73 to 78% to give an intermediate plate thickness of 0.62-0.
51m++, then heated to 800°C in a nitrogen gas atmosphere.
Intermediate annealing was performed for 2 minutes. Then, as shown in Table 2, two-way rolling was carried out at various rolling reductions in the range of 0.3 to 20%, each resulting in a final thickness of 0.50 mm. In addition, when rolling between these two large diameters, the rolling speed is also 10 to 2500.
Various changes were made within the range of m/1n. Thereafter, each of these cold-rolled sheets was subjected to short-time finish annealing at 800° C. for 2 minutes in a nitrogen gas atmosphere to produce an electrical steel sheet product.

Table 2 shows the relationship between the average B1 value in the rolling direction and the direction perpendicular thereto, the secondary cold rolling reduction ratio, and the rolling speed of each fully processed electrical steel sheet thus obtained.

As is clear from the table, a high B1 value of 0.7 T or more can be obtained when the rolling reduction in two-way rolling is 1 to 15% and the rolling speed is 500 m/min or more.

Furthermore, it has been confirmed that those with a high B1 value also have extremely small magnetic anisotropy.

(Effects of the Invention) As described above, according to the present invention, it is possible to easily obtain an electromagnetic steel sheet having extremely small magnetic anisotropy and excellent low magnetic field properties.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the average Bi value in the rolling direction and the direction perpendicular to the rolling direction of an electrical steel sheet after finish annealing, and the rolling reduction and rolling speed in two-way rolling, and Fig. 2 a to f. are graphs showing torque curves of electrical steel sheet products after final annealing. 0 σ Torgudakai a (dynl/Cf7+9
Torgu compensation degree n temporary) Lytrug strength ((lv-flying charge Torguda association degree nek Iv Toreguda cost degree (dyn plug Yu 9F Rug strength ('?”&* procedure correction book Showa 60 May 21, 1985 Patent application submitted on May 20, 1985 (1) Relationship with the case of the person making the first correction Patent applicant (125) Kawasaki Steel Co., Ltd. Correct contents of the column indicating "A patent application pursuant to the provisions of the Patent Act" and the column of "Number of inventions stated in the scope of claims" in the application (as attached) ``Patent application according to regulations'' is added.

Claims (1)

[Claims] 1. A hot rolled steel sheet having a composition containing 0.02 wt% or less of C and 0.1 to 4.5 wt% of Si is cold rolled twice with intermediate annealing in between. In producing an electrical steel sheet, the secondary cold rolling after the intermediate annealing is performed under conditions of a reduction ratio of 1 to 15% and a rolling speed of 500 m/min or more. A method for manufacturing semi-processed electrical steel sheets with low anisotropy and excellent low magnetic field properties. 2. A hot rolled steel sheet having a composition containing C: 0.02 wt% or less and Si: 0.1 to 4.5 wt% is cold rolled twice with intermediate annealing in between to produce an electrical steel sheet. In this case, the secondary cold rolling after the above-mentioned intermediate annealing is performed under the conditions of a reduction ratio of 1 to 15% and a rolling speed of 500 m/min or more, and then finish annealing is performed. A method for manufacturing full-process electrical steel sheets with low anisotropy and excellent low magnetic field properties.