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Non-Oriented Electrical Steel Sheet Having Superior Magnetic Properties and a Production Method Therefor

a technology of non-oriented electrical steel and magnetic properties, which is applied in the direction of inorganic material magnetism, etc., can solve the problems of difficult cold rolling, reduced processing efficiency, and reduced life of molds, and achieve excellent magnetic properties, increase the distribution density of coarse inclusions, and enhance the growth of grains and the mobility of domain walls

Inactive Publication Date: 2012-10-25
POHANG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0028]According to the present invention, the proportions of alloy elements such as Al, Si and Mn and of impurity elements such as N and S can be appropriately controlled so as to increase the distribution density of coarse inclusions, thus enhancing the growth of grains and the mobility of domain walls. Thereby, a non-oriented electrical steel sheet of the highest quality having excellent magnetic properties and very low hardness can be stably produced. Also customer workability and productivity are superior, and the unit cost of production of products can be decreased, thus reducing the cost.

Problems solved by technology

If the amount of Si is excessively increased, processability is decreased making it difficult to perform cold rolling.
Furthermore, the lifetime of a mold may decrease upon punching by the customer.
However, the magnetic properties of non-oriented electrical steel sheet of the highest quality are not obtained, and such sheets have not yet been actually produced because of difficulties in mass producing them.
However, the control of impurities to the minimum is not easy in a typical production process of electrical steel sheets, and the cost of a steel making process may undesirably increase.
The inclusions that are precipitated in typical non-oriented electrical steel sheets include MnS and AlN, which are observed to have a small average size of about 50 nm, and such fine inclusions may hinder the growth of grains upon annealing thus increasing hysteresis loss and obstructing the movement of domain walls upon magnetization, undesirably lowering permeability.

Method used

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  • Non-Oriented Electrical Steel Sheet Having Superior Magnetic Properties and a Production Method Therefor
  • Non-Oriented Electrical Steel Sheet Having Superior Magnetic Properties and a Production Method Therefor

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0098]Vacuum melting was performed in a laboratory, thus preparing steel ingots having the components shown in Table 1 below. As such, the amount of each of impurity elements C, S, N, Ti was controlled to 0.002%, and 0.3˜0.5% of Al was added to molten steel to facilitate the formation of inclusions, after which the remainder of Al, and Si and Mn were added thus making steel ingots. Each of the ingots was heated to 1,150° C., and finish hot rolled at 850° C. thus manufacturing a hot rolled sheet having a thickness of 2.0 mm. The hot rolled sheet was annealed at 1,050° C. for 4 min and then pickled. Subsequently, cold rolling was conducted so that the thickness of the sheet was 0.35 mm, followed by carrying out final annealing at 1,050° C. for 38 sec.

[0099]The size and distribution density of inclusions of respective sheets, the core loss, the magnetic flux density and hardness were measured. The results are shown in Table 2 below. A sample for use in observing the inclusions was manu...

example 2

[0102]Vacuum melting was performed in a laboratory, thus preparing steel ingots having the components shown in Table 3 below. As such, the components of steel were controlled while variously adjusting the amounts of impurity elements N and S, and 0.3˜0.5% of Al was added to molten steel to facilitate the formation of inclusions, after which the remainder of Al, and Si and Mn were added thus making steel ingots. Each of the ingots was heated to 1,1500, and finish hot rolled at 850° C. thus manufacturing a hot rolled sheet having a thickness of 2.0 mm. The hot rolled sheet was annealed at 1,050° C. for 4 min and then pickled. Subsequently, cold rolling was conducted so that the thickness of the sheet was 0.35 mm, followed by carrying out final annealing at 1,050° C. for 38 sec.

[0103]The size and distribution density of inclusions of respective sheets, the core loss, the magnetic flux density and hardness were measured. The results are shown in Table 4 below. A sample for observing the...

example 3

[0106]Vacuum melting was performed in a laboratory, thus preparing steel ingots having the components shown in Table 5 below. As such, 0.3˜0.5% of Al was added to molten steel to facilitate the formation of inclusions, after which the remainder of Al, and Si, Mn and P were added thus making steel ingots. Each of the ingots was heated to 1,150° C., and finish hot rolled at 850° C. thus manufacturing a hot rolled sheet having a thickness of 2.0 mm. The hot rolled sheet was annealed at 1,050° C. for 4 min and then pickled. Subsequently, cold rolling was conducted so as to form sheets having different thicknesses in the range of 0.15˜0.35 mm, followed by carrying out final annealing at 1,050° C. for 38 sec. The core loss and magnetic flux density of respective sheets having different thicknesses were measured. The results are shown in Table 6 below. A sample for observing the inclusions was manufactured using a replica method that is typical in the steel industry, and a transmission ele...

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Abstract

Provided are: a non-oriented electrical steel sheet having outstanding magnetic properties and comprising, as percentages by weight, from 1.0 to 3.0% of Al, from 0.5 to 2.5% of Si, from 0.5 to 2.0% of Mn, from 0.001 to 0.004% of N, from 0.0005 to 0.004% of S and a balance of Fe and other unavoidably incorporated impurities, wherein the Al, Mn, N and S are included so as to satisfy the compositional formulae {[Al]+[Mn]}≦3.5, 0.002≦{[N]+[S]}≦0.006, 300≦{([Al]+[Mn]) / ([N]+[S])}≦1,400; and a production method therefor. By optimising the Al, Si, Mn, N and S added components in this way, the distribution density of coarse inclusions is increased, thereby making it possible to improve crystal-grain growth properties and domain wall mobility and so produce the highest grade of non-oriented electrical steel sheet having superior magnetic properties, low hardness, and superior customer workability and productivity.

Description

TECHNICAL FIELD[0001]The present invention relates to the production of a non-oriented electrical steel sheet, and particularly to a non-oriented electrical steel sheet of the highest quality, wherein the components of steel are optimally designed to increase the distribution density of coarse inclusions in steel and to improve growth of grains and mobility of domain walls, so that magnetic properties are enhanced, and low hardness is ensured, thus improving productivity and punchability, and to a method of producing the same.BACKGROUND ART[0002]The present invention pertains to the production of a non-oriented electrical steel sheet useful as a material for iron cores of rotation devices. This non-oriented electrical steel sheet is essential in terms of converting electrical energy into mechanical energy, and thus the magnetic properties thereof are regarded as very important. The magnetic properties mainly include core loss and magnetic flux density. Because the core loss is energ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C21D8/02C22C38/06C22C38/04C22C38/02C22B9/00
CPCC21D8/12C21D2211/004C22C38/001C22C38/02C22C38/04H01F1/16C22C38/002C22C38/004C22C38/008C22C38/14C22C38/60C22C38/06
Inventor KIM, JAE-HOONKIM, JAE-KWANKIM, YONG-SOOBONG, WON-SEOG
Owner POHANG IRON & STEEL CO LTD
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