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

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Benefits of technology

[0121]The grounds for the limitations with regard to an embodiment of a manufacturing method according to the present invention will now be described below.
[0122]In the present invention, the manufacturing process from steelmaking to cold rolling may be performed in accordance with methods commonly used for manufacturing general non-oriented electrical steel sheets. For example, steel, which was prepared by steelmaking and refined with predetermined components in a converter or electric furnace, may be subjected to continuous casting or blooming after ingot casting to obtain steel slabs, which in turn may be subjected to process steps, including hot rolling, optional hot band annealing, cold rolling, final annealing, insulating coating application and baking, and so on to manufacture steel sheets. In these steps, the conditions for properly controlling the precipitation state will be described below. It should be noted that hot band annealing may optionally be carried out after the hot rolling, and that the cold rolling may be performed once, or twice or more with intermediate annealing performed therebetween.
[0123]The steel slabs composed of the aforementioned chemical compositions are to be subjected to hot rolling at a slab heating temperature of 1000° C. or higher to 1200° C. or lower. That is, if the slab heating temperature is below 1000° C., it is not possible to achieve an effect of inhibiting the growth of crystal grains during final annealing in a sufficient manner due to the precipitation and growth of Ti carbides during slab heating. Alternatively, if the slab heating temperature is above 1200° C., this is not only disadvantageous in terms of cost, but

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

Method used

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