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Non-oriented electrical steel sheet and method for manufacturing the same

a technology of non-oriented electrical steel and manufacturing method, which is applied in the direction of manufacturing tools, heat treatment process control, heat treatment apparatus, etc., can solve the problems of unavoidable heat generation of rotors, limitations of the design specification of motors, and inability to manufacture until now, so as to achieve the effect of low operability

Inactive Publication Date: 2013-11-21
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a method for manufacturing non-oriented electrical steel sheets with improved magnetic properties. The method involves adding specific elements to the steel composition, such as antimony, tin, boron, calcium, and REM, in small amounts without affecting the overall effect of the invention. The manufacturing process involves steps such as steelmaking, hot rolling, optional hot band annealing, cold rolling, final annealing, insulating coating application, and baking. The resulting steel sheets are then subjected to heat treatment at temperatures between 800°C and 950°C for at least 30 seconds to precipitate titanium carbides and inhibit the growth of crystal grains during final annealing. The technical effects of the invention include improved magnetic properties, strengthening by precipitation, and better control of oxide and sulfide formation.

Problems solved by technology

In the proposals made to date, however, it has not been possible until now to manufacture, with the use of an ordinary facility for manufacturing electrical steel sheets, such a high-strength non-oriented electrical steel sheet in an industrially stable manner with good yield and at low cost that has good magnetic properties in addition to high tensile strength and high fatigue strength, and furthermore, satisfy the quality requirements of steel sheet, such as those relating to surface defects, internal defects, sheet shape or the like.
Particularly, the high-strength electrical steel sheets that have so far been provided for rotors of high speed motors are in a situation where the resulting rotors will be subject to unavoidable heat generation due to their magnetic property, i.e., high iron loss at high frequency, which necessarily poses limitations on the design specification of the motors.
Thus, they are less effective for inhibiting the growth of crystal grains and not useful for crystal grain refinement control intended by the present invention.
However, there is a limit in adding these elements since excessive addition leads to embrittlement of steel and poses difficulty in manufacturing steel.

Method used

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  • Non-oriented electrical steel sheet and method for manufacturing the same
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  • Non-oriented electrical steel sheet and method for manufacturing the same

Examples

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example 1

[0128]Steel samples having compositions shown in Table 3 were obtained by steelmaking in a vacuum melting furnace, heated to 1100° C., and then subjected to hot rolling to be a thickness of 2.1 mm. Then, the samples were subjected to hot band annealing at 900° C. for 90 seconds and further to cold rolling to be finished to a thickness of 0.35 mm. At this moment, an evaluation was made of the occurrence of scab defects on the surfaces of the steel sheets, using the scab size per unit area as a reference. Subsequently, the samples were subjected to final annealing for 30 seconds under two different conditions at 750° C. and 800° C., respectively. Then, test specimens were cut parallel to the rolling direction from the steel sheet samples thus obtained for tensile test and fatigue test. In addition, the magnetic properties were evaluated based on the iron loss with a magnetizing flux density of 1.0 T and frequency of 400 Hz of the Epstein test specimens that were cut from the samples i...

example 2

[0130]Steel samples having compositions shown in Table 5 were obtained by steelmaking in a vacuum melting furnace, heated to 1050° C., and then subjected to hot rolling to be a thickness of 2.1 mm. Then, the samples were subjected to hot band annealing at 850° C. for 120 seconds and further to cold rolling to be finished to a thickness of 0.35 mm. At this moment, an evaluation was made of the occurrence of scab defects on the surfaces of the steel sheets, using the scab size per unit area as a reference. Subsequently, the steel samples were subjected to final annealing at 800° C. for 30 seconds. Then, test specimens were cut parallel to the rolling direction from the steel sheet samples thus obtained for tensile test and fatigue test. In addition, the magnetic properties were evaluated based on the iron loss with a magnetizing flux density of 1.0 T and frequency of 400 Hz of the Epstein test specimens that were cut from the samples in the rolling direction and transverse direction, ...

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Abstract

The present invention provides a non-oriented electrical steel sheet at low cost that has excellent magnetic properties and mechanical properties as well as excellent quality of steel sheet. The non-oriented electrical steel sheet has a chemical composition containing, by mass %, Si: 5.0% or less, Mn: 2.0% or less, Al: 2.0% or less, and P: 0.05% or less, in a range satisfying formula (1), and furthermore, C: 0.008% or more and 0.040% or less; N: 0.003% or less, and Ti: 0.04% or less, in a range satisfying formula (2), with the balance composed of Fe and incidental impurities:300≦85[Si %]+16[Mn %]+40[Al %]+490[P %]≦430  (1)0.008≦Ti*<1.2[C %]  (2),where Ti*=Ti−3.4[N %].

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This is the U.S. National Phase application of PCT / JP2011 / 001074, filed Feb. 24, 2011, the disclosure of which is incorporated herein by reference in its entirety for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to a non-oriented electrical steel sheet, and in particular, to a non-oriented electrical steel sheet having high strength and excellent fatigue properties, and furthermore, excellent magnetic properties that is suitably used for components that are subject to high stress, typically, drive motors for turbine generators, electric vehicles and hybrid vehicles, or rotors for high-speed rotating machinery, such as servo motors for robots, machine tools or the like, and a method for manufacturing the same. Additionally, the present invention provides the above-described non-oriented electrical steel sheet at low cost as compared to the conventional art.BACKGROUND OF THE INVENTION[0003]As recent, advances in mot...

Claims

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Application Information

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IPC IPC(8): C22C38/60C22C38/16C22C38/14C22C38/00C22C38/08C22C38/06C22C38/04C22C38/02C21D8/12C22C38/10
CPCC22C38/60C21D8/12C22C38/16C22C38/14C22C38/10C22C38/08C22C38/06C22C38/04C22C38/02C22C38/008C22C38/005C22C38/004C22C38/002C22C38/001H01F1/16C21D8/1227C21D8/1266C21D8/1272
Inventor KOHNO, MASAAKIZAIZEN, YOSHIAKIODA, YOSHIHIKOFUJITA, AKIRA
Owner JFE STEEL CORP
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