KR920004950B1 - Making process for the electric steel plate - Google Patents

Abstract

A fabrication method for electric plate, which composition is >=

Description

Method for manufacturing non-oriented electrical steel sheet with excellent magnetic properties

1 is a graph showing the magnetic change of the final product according to the annealing temperature of the cold rolled sheet.

The present invention relates to a non-oriented electrical steel sheet manufacturing method used as iron cores of various electrical equipment, and more particularly, by adding a small amount of Sb and Zr to the non-oriented electrical steel sheet excellent magnetic properties even at low temperature annealing It relates to a method capable of manufacturing non-oriented electrical steel sheet.

Non-oriented electrical steel sheets containing 1.5% or less of Si have a wide range of applications from small and medium motors, which occupy most electric equipment, to iron cores for small transformers. In addition, by increasing the magnetic flux density and permeability, the device is miniaturized and the efficiency is increased.

Iron loss is classified into fire loss and hysteresis loss. Vortex loss is determined by composition and thickness, whereas hysteresis loss is greatly affected by grain size and texture of material.

The reduction of vortex loss in the silicon steel sheet is mainly determined by the amount of Si. The more Si, the more the vortex loss is reduced, but the higher the manufacturing cost.

In order to improve iron loss, it is more economical to add a small amount of special elements or to secure proper manufacturing conditions. Therefore, a method of reducing hysteresis loss is mainly a problem.

Hysteresis losses vary somewhat from material to material, but are generally reduced with larger grain sizes.

As a method of growing grains to reduce hysteresis loss, there is known a method of inhibiting N component, which is an invasive impurity element, in order to prevent fine precipitation of nitride or to coarse these precipitates. In this case, in addition to the grain size, it is possible to improve the aggregate structure, thereby improving the magnetic properties.

The aggregated tissue is preferably developed in the (200) plane and the (110) plane which is advantageous for magnetization. The development of page 220 should be ruled out as far as possible.

As such, by growing grains and developing aggregates, magnetic flux density and permeability can be improved.

The magnetic flux density and magnetic permeability are magnetic properties that determine the efficiency of the motor, and the higher the efficiency, the smaller the device can be, and thus the power loss can be reduced.

Conventionally, elements such as Sb have been added to increase Si to increase the amorphousness or to control the texture and grains.

However, in order to reduce iron loss, increasing Si lowers the magnetic flux density and permeability, and increases the manufacturing cost.

In Japanese Patent Publication No. 56-54370, Sb-added steel is proposed. In this patent, Sb segregates at grain boundaries, develops an aggregate structure such as (200) cotton which is advantageous for magnetization, and suppresses the growth of new grains. It states that grains can be coarsened.

The inventors of the present invention are capable of omitting pre-annealing of the hot rolled sheet by adding Sb and Zr, and improving the magnetic properties by pre-annealing the hot rolled sheet, and to produce an excellent non-oriented electrical steel sheet capable of low temperature annealing of the cold rolled sheet. , Its purpose is.

In general, Zr forms fine precipitates to suppress grain growth and suppresses the movement of magnetic domains to increase iron loss. However, Zr has been inhibited in use, but steels added with Zr and Sb as trace elements are hot rolled after steelmaking. The magnetic properties are excellent even at low temperature annealing, and the magnetic properties are further improved by pre-annealing after hot rolling.

Since Zr has strong bonding force with N, most of it can be denitrified by ZrN in the off-road process of steelmaking, and the magnetism is improved. Some remaining N is precipitated as coarse ZrN even by hot rolling, but is pre-annealed after hot rolling. Since coarse precipitates are more easily formed, the formation of fine precipitates such as AlN can be rather suppressed, so that the magnetic properties are improved even by low temperature annealing.

Even if the steel added with Zr and Sb simultaneously annealed the cold rolled sheet at low temperature, it is believed that the superiority of the magnetic properties is due to the reduction of N in steelmaking by the addition of Zr and the growth of grains by the addition of Sb.

In general, Sb-added steel improves magnetism by pre-annealing the hot rolled sheet, but it is possible to secure good magnetic properties without pre-annealing by adding Zr to it, and this effect is more effective when hot-rolled steel sheet is annealed before cold rolling. Grows

The present invention, in weight%, C: 0.01% or less, Si: 1.5% or less, Mn: 0.15-1.0%, P: 0.10% or less, S: 0.07% or less, Al: 0.060% or less, Sb: 0.01-0.30 %, And Zr: slab containing 0.005-0.10% and composed of the remaining Fe and other unavoidable impurities, hot-rolled in a conventional manner, followed by one-stage cold rolling or two-stage cold including skin pass after pickling The present invention relates to a method for producing a non-oriented electrical steel sheet having excellent magnetic properties for cold rolling a hot rolled sheet by a rolling method.

In addition, the present invention, in weight%, C: 0.01% or less, Si: 1.5% or less, Mn: 0.15-1.0%, P: 0.10% or less, S: 0.07% or less, Al: 0.60% or less, Sb: 0.01 A slab containing -0.30%, and Zr: 0.005-0.10% and composed of the remaining Fe and other inevitably added impurities, was hot-rolled in a conventional manner, and the hot-rolled sheet was then heated at 750 ° C.-900 ° C. at 1-10 ° C. Excellent non-directional magnetic properties for cold rolling hot rolled sheet by one-stage cold rolling method or two-stage cold rolling method including skin pass after preliminary annealing by continuous continuous annealing for 10 minutes or 10 minutes It relates to a method of manufacturing electrical steel sheet.

Hereinafter, the reason for component limitation will be described.

C is one of the most influential elements in magnetic properties, and the lower the final product is, the more advantageous it is, and it is less than 0.003%, which can suppress the magnetic aging. It can also be decarburized.

Si is able to reduce iron loss by increasing the specific resistance to reduce eddy current loss, and it should be less than 1.5% in consideration of increase in manufacturing cost, cold rolling, magnetic flux density and permeability.

Al is a strong ferrite-forming element and its iron loss decreases due to the increase of its content, but it should be less than 0.60% considering the rolling workability and manufacturing cost, and considering the magnetic improvement due to the addition amount.

P suppresses grain growth and deteriorates the texture, but in non-oriented electrical steel sheets with low Si, the punchability is improved by increasing the hardness, so it is 0.10% or less.

S is limited to 0.007% or less because it inhibits grain growth by promoting the precipitation of fine MnS and promotes the texture of the (222) plane. The target management should be less than 0.003% by charter preliminary treatment or desulfurization during refining.

Sb lowers the S content and preanneals the hot-rolled sheet to develop a magnetically favorable aggregate, and segregates at grain boundaries to promote the formation of a (200) facet favorable for magnetism and to grow grains by inhibiting the formation of new grains. In consideration of the influence of Sb addition and cold rolling, the slab is 0.01-0.30%.

Mn is controlled at 0.15-1.0%, and when added below 0.15%, the texture of the (222) plane becomes strong, and when added more than 1.0%, the rolling workability is deteriorated.

Zr is combined with N in the steel to suppress the formation of fine nitride, and ZrN is removed during steelmaking or coarsened in the post-process to minimize the influence of N to improve the magnetic properties.

However, when a large amount of Zr is added, plate breakage may occur during rolling, and when it exceeds 0.10%, the magnetism is deteriorated, so it is added below 0.10%, and at least 0.005% or more in consideration of the amount consumed during post-processing such as hot rolled material heating. Is added.

Hereinafter, the rolling and annealing step in the present invention will be described.

The slab formed in the above component range is cracked at a reheating temperature of 1200 ° C. or higher, and then hot rolled in a conventional manner, and the hot rolled plate may be cold rolled after pickling, but the hot rolled plate may be subjected to 1 minute at 750-950 ° C. to It is more preferable to perform cold rolling after continuous annealing for 10 minutes or pre-annealing for 10 minutes to up to 10 hours by cold annealing. The reason for the pre-annealing as described above is that the precipitates are larger in the hot-rolled sheet and thus more magnetic. To improve.

Of course, the magnetic flux density and permeability are excellent even without performing the pre-annealing, and the pre-annealing or the pre-annealing method can be changed according to the required magnetic properties.

The cold rolling may be performed by a one-stage cold rolling method in which the hot rolled sheet is cold rolled by an ordinary method, followed by annealing the cold rolled plate. Alternatively, the cold rolled sheet may be subjected to cold rolling and annealing followed by skin pass rolling. It is preferable to perform annealing at 600-850 degreeC for 5 second-10 minutes.

In addition, the cold rolling process may be a two-stage cold rolling method in which the hot rolled sheet is first cold rolled by an ordinary method, followed by intermediate annealing, second cold rolling, and then annealing. The annealing after the second cold rolling is performed at 600-850. It is preferable to carry out for 5 seconds to 10 minutes.

When the annealing temperature is too low during annealing the cold rolled sheet, the grain growth is insufficient, and even if too high, the magnetic properties are bad, so the annealing temperature is preferably 600-850 ° C.

The product obtained by performing the above skin pass rolling is referred to as a general semi-process non-oriented electrical steel sheet, while the product which performs cold rolling in the first or second stage is called a polyprocess non-oriented electrical steel sheet, and the semi-process material is skin pass rolling. After the demand is processed and the demand is heat-treated, there is a difference between the two processes that the demand is processed after annealing of the polyprocess material which is subjected to the cold rolling which is finished first or second.

The final cold rolled sheet (polyprocess material) can be annealed at 600-850 ° C for 5 seconds to 10 minutes, and the demand can be annealed at 700-900 ° C for 20 minutes to 2 hours to ensure better magnetic properties. The ash can be obtained by annealing the cold rolled plate in the same manner as the polyacetic material, followed by skin pass rolling and stress relief annealing.

When annealing, the annealing atmosphere is preferably annealed in a mixed atmosphere with 100% nitrogen or hydrogen.

The present invention will be described through the following examples.

Example 1

The slab having the composition shown in Table 1 was heated to 1250 ° C., and then hot rolled to a thickness of 2.1 mm, and the hot rolled plate was treated as shown in Table 2, followed by cold rolling after removing the pickling scale. The thickness of the cold rolled sheet of the polyprocess material was The thickness of the semi-process material after the cold rolling was 0.5 mmt. The cold rolled sheet was annealed in 100% nitrogen atmosphere for 1 minute.

The polyprocess material was cut after annealing and annealed in a mixed atmosphere of nitrogen and hydrogen for 1.5 hours at 790 ° C., and the semiprocess material was measured after annealing and cut in the same manner after skin pass. Shown in

The iron loss and permeability of Table 2 are 50 Hz and 1.5 Tesla, and the magnetic flux density is a magnetic measurement value when a magnetic field of 5000 A / m is applied, and a skin pass material is a polyprocess material.

TABLE 1

TABLE 2

As shown in Table 2 above, the present invention steels (A, B and F) to which Sb and Zr are added in accordance with the present invention are hot rolled, and the hot rolled sheet is pre-annealed or pre-annealed without cold pre-annealing. Alternatively, a comparative material (1-15) in which the inventive material (ah) that is cold rolled by skin pass rolling is treated with comparative steel (CE) in which the amount of Sb and Zr added is outside the scope of the present invention under the same condition as the inventive material (ah) (1-15). It can be seen that the magnetic properties are superior to).

Example 2

In wt%, C: 0.004%, Si: 0.032%, Mn: 0.31%, P: 0.043%, S: 0.003%, Al: 0.003%, N: 0.0015%, Sb: 0.065%, Zr: 0.051% and the balance The steel slab made of Fe was held at 1230 ° C. for 2 hours, hot rolled to 2 mm in thickness, and then preannealed at 800 ° C. for 5 minutes and pickled.

The pickled hot rolled sheet was cold rolled and annealed in a nitrogen atmosphere for 1 minute by changing the annealing temperature to 600-850 ° C.

The semi-process material was cut after 4% skin pass rolling and stress-annealed at 790 ° C for 2 hours with a polyspores material. The magnetic properties were measured and the results are shown in FIG.

Further, in order to investigate the effect of annealing on the material of the same component, the hot-rolled sheet treated as above is subjected to annealing at 800 ° C. for 2 hours, and then cold-rolled sheet annealing is performed at 730 ° C. for 1 minute, as shown in Table 3 below. Skin pass rolling was carried out by varying the skin pass rate, stress relief annealing was performed at 790 ° C. for 2 hours, and the magnetic properties were measured and shown in Table 3 below.

TABLE 3

In Table 3, as the skin pass rate was increased to 0%, 5%, 9%, and 14%, the grains were 58 μm, 98 μm, 101 μm, and 73 μm, respectively. .

The skin pass rolling material is advantageous for grain growth because it is possible for the stress grain growth in which grains are grown by the stress added by skin pass rolling during heat treatment after the skin pass rolling.

As shown in Figure 1, when the pre-annealed hot-rolled sheet according to the present invention, both the semi-process material and the poly-process material showed excellent magnetic properties, and as shown in Table 3, the hot-rolled plate according to the present invention As a result, even after annealing the skin pass rolling it can be seen that the magnetic properties are excellent.

As described above, the present invention is a non-oriented electric steel containing 1.5% or less of Si and 0.01-0.30% Sb and 0.005-0.10% Zr, and having excellent magnetic properties even at low temperature annealing of the cold rolled sheet. There is an effect that can produce a steel sheet.

Claims (2)

C: 0.01% or less, Si: 1.5% or less, Mn: 0.15-1.0%, P: 0.10% or less, S: 0.07% or less, Al: 0.060% or less, Sb: 0.01-0.30%, and Zr: 0.005-0.10 The slab containing% and containing the remaining Fe and other inevitable impurities are hot rolled by a conventional method, and then cold rolled the hot rolled sheet by a single stage cold rolling method or a two stage cold rolling method including a skin pass. Method for producing non-oriented electrical steel sheet having excellent magnetic properties. C: 0.010% or less, Si: 1.5% or less, Mn: 0.15-1.0%, P: 0.10% or less, S: 0.007% or less, Al: 0.60% or less, Sb: 0.01-0.30%, and Zr: 0.005-0.10 A slab containing% and consisting of the remaining Fe and other inevitably added impurities is hot rolled in a conventional manner, and then the hot rolled sheet is continuously annealed at 750-900 ° C. for 1-10 minutes or 10 minutes-10 hours. A method of manufacturing a non-magnetic electrical steel sheet having excellent magnetic properties, characterized in that the hot rolled sheet is cold rolled by a first stage cold rolling method or a two stage cold rolling method including a skin pass after preannealing by ordinary annealing.

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