JPH02194123A - Manufacture of nonoriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To manufacture a nonoriented silicon steel sheet reduced in iron loss, having high magnetic flux density, and excellent in magnetic properties by applying rapid solidification to a molten steel containing specific weight percentage of Si to form a steel strip, hot-rolling the above at specific draft and specific finishing temp., and then subjecting the above to cold rolling and annealing. CONSTITUTION:A molten steel having a composition consisting of, by weight, 0.1-4.0% Si and the balance essentially Fe is rapidly solidified by means of a renewedly moving cooling-body surface so as to be formed into a steel strip. This steel strip is hot-rolled, without reheating, at <=60% draft and 600-1000 deg.C rolling finishing temp. Then, cold rolling and finish annealing are applied to the above hot rolled steel strip. At this time, cold draft is regulated to 30-<80% or to >=80%. By this method, the nonoriented silicon steel for iron core material for high performance electrical equipment can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a non-oriented electrical steel sheet with excellent magnetic properties, which is used as a core material for electrical equipment.

[Conventional technology]

In recent years, there has been a strong demand for higher efficiency in electrical equipment amid the global movement to save electricity and energy.

For this reason, there is an increasing demand for non-oriented electrical steel sheets, which are widely used as iron core materials for rotating machines and small and medium-sized transformers, to have low iron loss and high magnetic flux density.

In conventional non-oriented electrical steel sheets, Si is generally used as a means of reducing iron loss from the viewpoint of reducing eddy current loss due to increased specific resistance.
Alternatively, methods have been used to increase the content of M, etc.
However, this method has a problem in that the magnetic flux density decreases.

In addition, from the viewpoint of reducing hysteresis loss by improving the texture, hot-rolled sheet annealing or JP-A-59-1
As described in JP-A No. 57259 and JP-A No. 60-3912, etc., there is a method of reducing iron loss and increasing magnetic flux density at the same time by combining hot-rolled sheet annealing and addition of trace elements such as Sn and Sb. However, there are problems in that the manufacturing process becomes longer and costs increase.

On the other hand, as described in Japanese Unexamined Patent Publication No. 56-3625, etc., an electromagnetic steel having a (100) in-plane non-directional texture that is produced directly into a ribbon by a rapid solidification method and which is preferable in terms of magnetic properties. A method of manufacturing a thin ribbon has been proposed. However, as mentioned at the beginning, non-oriented electrical steel sheets are used as core materials for electrical equipment, but in this case, strict requirements are placed on sheet thickness accuracy and shape. Therefore, rather than using the ribbon obtained by the rapid solidification method as it is as a core material for electrical equipment, it is preferable to improve the thickness accuracy and shape the ribbon by rolling or the like. However, applying rolling or the like to the ribbon may result in destruction of the metal structure, texture, etc., which are formed by the rapid solidification method and are favorable in terms of magnetic properties.

[Problem to be solved by the invention]

In view of the above circumstances, the present invention uses a steel strip obtained by a rapid solidification method as a starting material, applies it to processes including hot rolling and cold rolling, and then produces a non-oriented electrical steel sheet with excellent magnetic properties. The present invention provides a method for manufacturing.

[Means to solve the problem]

The present inventors have discovered that when hot-rolling and cold-rolling are applied to the strip obtained by the above-described rapid solidification method for the purpose of improving plate thickness accuracy and correcting the shape, the steel strip has a preferable magnetic property. We conducted extensive research from the viewpoint of finding hot rolling and cold rolling conditions that would not destroy the structure and texture.

As a result, it was discovered that when a steel strip obtained by rapid solidification is hot rolled under certain conditions without reheating, excellent magnetic properties can be obtained in combination with cold rolling and finish annealing. did.

The present invention has been made based on this knowledge, and the gist thereof is to move and renew molten steel containing Si: 0.1% to 4.0%, with the remainder substantially consisting of Pe. The surface of the cooling body causes rapid solidification to form a steel strip.
The steel strip is hot rolled without reheating at a reduction rate of 60% or less and a finishing temperature of 600°C or more and 1000°C or less, and then
The patented method for manufacturing non-oriented electrical steel sheets is characterized by subjecting the obtained hot-rolled steel strip to cold rolling and final annealing. Another gist of the present invention is that in the method for manufacturing a non-oriented electrical steel sheet, the cold rolling reduction ratio of the hot rolled steel strip is set to 30% or more and less than 80%. Yet another gist is that in the method for producing a non-oriented electrical steel sheet, the cold rolling reduction of the hot rolled steel strip is 80% or more.

The present invention will be explained in detail below.

The steel composition is Si: 0. It contains 1% or more and 4.0% or less, with the remainder essentially consisting of Pe. As is well known, Si is a component that has the effect of reducing iron loss, and in order to exhibit this effect, it must be contained in an amount of 0.1% or more. On the other hand, as its content increases, the magnetic flux density decreases,
Further, since it causes deterioration in workability and high cost in hot rolling and cold rolling, it is set to 4.0% or less.

In the present invention, steel components other than Si include ^1- Mn+ PI B + Nf+ for the purpose of improving magnetic properties, improving mechanical properties, improving induction resistance, etc.
Cr+Ti, V. One or more of Nb and Zr may be contained.

The content of each of the above components in weight percent is as follows.

A7: 2. 0% or less, Mn: 2.0% or less, p:
o. s% or less, Cr: 8.0% or less, Ni: 4.0% or less, Ti: 0, 3% or less, V: O. 3% or less, Nb: 0
．． Less than 3%.

Zr: 0. 3% or less, B: 0.01% or less.

Next, the relationship between the hot rolling conditions of a steel strip obtained by rapidly solidifying molten steel and the magnetic properties after cold rolling and finish annealing, which is a feature of the present invention, will be explained.

FIG. 1 shows Si: 1. Molten steel containing 1% was continuously cast using a twin roll method and rapidly solidified to give thicknesses of 5.0 mm and 4.011111. 3.5M
, 3.0M.

2.0 m of 5 types of strips were prepared, and then these steel strips were heated at a finishing temperature of 850°C without reheating.
The magnetic properties of the product sheet were hot-rolled to a flat thickness, then cold-rolled to a thickness of 0.501 IIm (cold-rolling reduction: 66.7%), and subjected to continuous finish annealing at 850°C for 30 seconds. These are the measured results. It can be seen that when the hot rolling reduction ratio of the steel strip obtained by rapid solidification is 60% or less, a product sheet with extremely low iron loss, high magnetic flux density, and excellent magnetic properties can be manufactured. This means that the hot rolling reduction rate of the steel strip is 60
%, as shown in the example in Figure 2 (a),
The structure of the steel strip changes completely to a rolled structure and a part to a recrystallized structure, but when the hot rolling reduction of the steel strip is 60% or less, the structure changes to the example shown in Fig. 2 (b). As shown, this is because the structure of the steel strip obtained by rapid solidification is almost preserved.

Note that the hot rolling of the strip may be carried out after reheating the strip, but as a result of the metal structure, texture, etc., which is formed by the rapid solidification method and is favorable for magnetic properties, being changed during reheating. becomes. Therefore, the steel strip needs to be hot rolled without being reheated. Further, even when the hot rolling finishing temperature exceeds 1000° C., the metal structure, texture, etc., which are formed by the rapid solidification method and are preferable in terms of magnetic properties, are susceptible to change. On the other hand, when the hot rolling finishing temperature is less than 600°C, the shape straightening effect is small, the load on the hot rolling mill increases, the workability deteriorates, and the magnetic properties also decrease when the hot rolling finishing temperature is 600°C or higher. Since no improvement was observed compared to the case of , the hot rolling finishing temperature was set at 6.
The temperature was 00°C or higher.

As described above, the feature of the present invention is that S obtained by rapid solidification
A steel strip with an i content of 0.1% or more and 4.0% or less should not be reheated (reduction rate of 60% or less, finishing temperature of 600°C).
By hot rolling at 1000° C. or lower, cold rolling and final annealing, a non-oriented electrical steel sheet with low iron loss and high magnetic flux density can be manufactured.

By the way, it goes without saying that cold rolling has the effect of increasing the plate thickness accuracy and adjusting the shape (flatness), but especially when the cold rolling reduction is 30% or more and less than 80%, the cold rolling improves the plate thickness accuracy. In addition to improving the shape and correcting the shape, it also has the effect on magnetic properties that the magnetic flux density becomes even higher. Also,
When the cold rolling reduction is 80% or more, the plate thickness accuracy is improved,
In addition to the shape correction effect, the texture of the product board is (100)
Since it approaches the (025) type, it also has the effect on magnetic properties that both core loss and magnetic flux density are significantly reduced in-plane anisotropy.

[Example] Next, Example I showing an example of the present invention Si: 3.0%, AJ: 1, Q%, Mn: 0.2%5
Molten steel containing 0.02% P, with the remainder essentially consisting of Pe, was rapidly solidified by the twin roll method to a thickness of 4.0%.

Three types of strips, 3.0 mm and 2.0 mm, were prepared, and then these steel strips were heated to a finishing temperature of 820 mm without reheating.
℃ to a thickness of 1.4 m, and then cold rolled to a thickness of 0.35 m at a cold rolling reduction of 5.0%) and 30 m at 1050″C.
Continuous finish annealing was performed for seconds, and the magnetic properties were measured. The measurement results are shown in Table 1. It can be seen that according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet with extremely low core loss and high magnetic flux density.

Table 1 Example 2 Si: 1.0%, AJ: 0.03%, Mn: 0.2%,
Molten steel containing 0.01% P, 3% B: o, oo, and the remainder substantially consisting of Pe was rapidly solidified using the twin roll method, and two types with thicknesses of 5.0 tm and 2.0 m were prepared. These steel strips were then processed into 5.0 nun thick steel strips without reheating at a finishing temperature of 880°C.
．． 4 thickness and 3.5 mm thickness, also 2.0 ++
A thick steel strip is then hot-rolled to a thickness of 1.4 mm, and the next step is
, 50III11 thickness, continuous finish annealing was performed at 900° C. for 20 seconds, and the magnetic properties were measured. The measurement results are shown in Table 2.6 It is clear that by the present invention, it is possible to produce a non-directional M1 steel plate having low iron loss, high magnetic flux density, and excellent magnetic properties. In particular, in the case of steel strip 5 with a cold rolling reduction of 80% or more, it is also clear that the difference in magnetic properties between the rolling direction and the direction perpendicular thereto is extremely small.

Example 3 Si: 3.4%, A7: Q, 7%, Mn: 1.0%, N
Molten steel containing t: 2.5%, Ti: 0.1%, and the remainder substantially consisting of Pe, was rapidly solidified by a twin roll method.
, two types of steel strips with a thickness of 0 mm and a thickness of 1.8 am,
Thereafter, these strips were hot-rolled to a thickness of 1.2 m at a finishing temperature of 950''C without reheating, and then cold-rolled to a body thickness of 0.20 mm with a cold rolling reduction of 8.3.3%). ,750℃
Continuous finish annealing was performed for 30 seconds, and the magnetic properties were measured. The measurement results are shown in Table 3. It can be seen that according to the present invention, a non-oriented electrical steel sheet with low core loss and high magnetic flux density can be manufactured.

Example 4 Molten steel containing 2.5% Si and 5.0% Cr, with the remainder essentially consisting of Pe, was rapidly solidified by a twin roll method,
Two types of steel strips with a thickness of 4.5 mm and a thickness of 2.5 mm were prepared, and then these steel strips were heated to a finishing temperature of 9 without reheating.
It was hot rolled to a thickness of 1.5M at 00℃, then cold rolled to a thickness of 0.5m (cold rolling reduction: 66.7%), and rolled at 950''C to a thickness of 3.
Continuous finish annealing was performed for 0 seconds, and the magnetic properties were measured. The measurement results are shown in Table 4.

It can be seen that according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet with low iron loss and high magnetic flux density.

Table 4 Table 3 [Effects of the Invention] As described above, according to the present invention, a non-oriented electrical steel sheet with low iron loss and high magnetic flux density and excellent magnetic properties can be obtained.
As electric equipment becomes more efficient, it is possible to fully meet the demand for non-oriented electrical steel sheets used as core materials, and its industrial effects are extremely large.

[Brief explanation of the drawing]

Figure 1 shows the hot rolling reduction ratio when molten steel containing 1.1% Si is rapidly solidified into a steel strip using the twin roll method, and then the strip is hot rolled without reheating. , iron loss W15/S of the product sheet after cold rolling and final annealing. and magnetic flux density B,. Figure 2 is a metallurgical micrograph showing the metal structure of the steel strip when the hot rolling reduction shown in Figure 1 is 70% (a) and 25% (b). It is a diagram. Figure 1 Hot rolling reduction ratio (,%)

Claims (3)

[Claims] (1) Molten steel containing Si: 0.1% to 4.0% by weight, and the remainder substantially consisting of Pe, is rapidly solidified into a steel strip on the surface of a moving and renewing cooling body, and is made into a steel strip. It is characterized in that the steel strip is hot rolled without reheating at a reduction rate of 60% or less and a finishing temperature of 600°C or more and 1000°C or less, and then the obtained hot rolled steel strip is subjected to cold rolling and finish annealing. A method for manufacturing non-oriented electrical steel sheets with excellent magnetic properties. (2) The method for producing a non-oriented electrical steel sheet with excellent magnetic properties according to claim 1, wherein the cold rolling reduction of the hot rolled steel strip is 30% or more and less than 80%. (3) The method for producing a non-oriented electrical steel sheet with excellent magnetic properties according to claim 1, wherein the cold rolling reduction of the hot rolled steel strip is 80% or more.