High-strength steel sheet, and production method therefor

A high-strength steel sheet and a technology for manufacturing methods, which are applied in the directions of manufacturing tools, chemical instruments and methods, furnaces, etc., can solve problems such as inability to apply to automobile parts, and achieve the effects of high-strength formability, suppression of generation, and excellent platability.

Active Publication Date: 2019-04-16
JFE STEEL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Steel sheets with insufficient stretchability cannot be used for automotive parts due to defects such as cracks during forming

Method used

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  • High-strength steel sheet, and production method therefor
  • High-strength steel sheet, and production method therefor
  • High-strength steel sheet, and production method therefor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0118] For a steel raw material with a wall thickness of 250 mm having the composition shown in Table 1, the balance being Fe and unavoidable impurities, the hot rolling process is carried out under the hot rolling conditions shown in Table 2 to make a hot-rolled sheet, and the The cold rolling step with a cold rolling ratio of 40% to 80% yields a cold-rolled sheet having a thickness of 1.0 to 2.0 mm, and the annealing step is performed under the conditions shown in Table 2 to obtain a steel sheet. Then, hot-dip galvanizing was performed on the obtained steel sheet to form a hot-dip galvanized layer (GI material) on the surface. In addition, for some of the steel sheets on which the hot-dip galvanized layer was formed, after the hot-dip galvanized layer was formed, an alloying treatment was performed at the alloying temperature described in Table 2 to form an alloyed hot-dip galvanized layer (GA material). The steel sheets up to the annealing process were produced on a direct ...

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Abstract

Provided is a high-strength steel sheet which has a tensile strength of 980 MPa or higher, and excellent mouldability. This high-strength steel sheet has a specific component composition, and a structure in which the average grain size of a ferrite phase is 1.5 microns or lower, the area ratio of the ferrite phase is at least 2% but not more than 15%, the area ratio of a tempered martensite phaseis at least 75% but not more than 96%, and the total value of the lengths of interfaces between an untempered martensite phase and the ferrite phase, and the lengths of interfaces between the untempered martensite phase and the tempered martensite phase, per unit area, is at least 6.3*108 microns/m2 but not more than 5.0*1011 microns/m2.

Description

technical field [0001] The invention relates to a high-strength steel plate and a manufacturing method thereof. Background technique [0002] In recent years, from the point of view of protecting the global environment, the entire automobile industry has focused on limiting CO 2 emissions for the purpose of trying to improve the fuel efficiency of the car. To improve the fuel efficiency of automobiles, it is most effective to reduce the weight of automobiles by reducing the thickness of used parts. In recent years, the use of high-strength steel sheets as raw materials for automobile parts has gradually increased. [0003] On the other hand, the formability of steel sheets tends to deteriorate as the strength increases. Therefore, in addition to high strength, a steel sheet excellent in formability is desired. A steel sheet with insufficient stretchability cannot be used for automobile parts or the like due to defects such as cracks during forming. In order to reduce the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D9/46C22C18/00C22C38/38C22C38/58C23C2/06C23C2/28
CPCC23C2/06C23C2/28C21D9/46C22C18/00C22C38/38C22C38/58B32B15/013C21D6/002C21D6/004C21D6/005C21D6/008C21D8/0205C21D8/0226C21D8/0236C21D8/0263C21D1/26C22C38/001C22C38/02C22C38/06C22C38/22C22C38/24C22C38/28C22C38/32C22C38/34C22C38/42C22C38/50C22C38/54C21D2211/005C21D2211/008C23C2/40C23C2/29C22C38/002C22C38/44
Inventor 高坂典晃樱井理孝铃木克一姬井善正
Owner JFE STEEL CORP
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