High-strength steel sheet excellent in workability and cold brittleness resistance, and manufacturing method thereof

A manufacturing method and steel plate technology, applied in the direction of manufacturing tools, furnace types, furnaces, etc., can solve the problems of insufficient assurance of low-temperature brittleness and deterioration of low-temperature brittleness, and achieve the effect of excellent strength and ductility and excellent balance

Inactive Publication Date: 2012-12-19
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, if the strength is increased, the low-temperature brittleness will deteriorate. Therefore, in the above-mentioned steel sheets that have been provided for the purpose of improving the strength and workability, the low-temperature brittleness cannot be sufficiently ensured, so further improvement is required.

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  • High-strength steel sheet excellent in workability and cold brittleness resistance, and manufacturing method thereof
  • High-strength steel sheet excellent in workability and cold brittleness resistance, and manufacturing method thereof
  • High-strength steel sheet excellent in workability and cold brittleness resistance, and manufacturing method thereof

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Embodiment Construction

[0022] The inventors of the present invention have made intensive studies in order to improve the workability and low-temperature brittleness of high-strength steel sheets having a tensile strength of 1180 MPa or more. As a result, it was found that in order to obtain a high-strength steel sheet that not only maintains a high strength of 1180 MPa or more, but also has excellent workability and low-temperature brittleness, if the composition is properly controlled, the metal structure of the steel sheet can be changed to ferrite in a specific ratio. body, retained austenite (hereinafter referred to as "retained γ"), MA structure, bainitic ferrite and / or tempered martensite, if the metal structure is properly controlled, both strength and workability can be ensured , and can improve the low-temperature brittleness, thereby completing the present invention. In particular, the present invention is characterized in that it is found that a mixed structure (MA structure: Martensite-A...

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Abstract

The invention relates to a steel sheet having a tensile strength of 1180 MPa or more, the steel sheet excels in workability and cold brittleness resistance. The high-strength steel sheet contains 0.10% to 0.30% of C, 1.40% to 3.0% of Si, 0.5% to 3.0% of Mn, 0.1% or less of P, 0.05% or less of S, 0.005% to 0.20% of Al, 0.01% or less of N, 0.01% or less of O, as well as Fe and inevitable impurities. The steel sheet has: (i) a ferrite volume fraction of 5% to 35% and a bainitic ferrite and / or tempered martensite volume fraction of 60% or more; (ii) a MA constituent volume fraction of 6% or less (excluding 0%); and (iii) a retained austenite volume fraction of 5% or more.

Description

technical field [0001] The present invention relates to a high-strength steel sheet excellent in workability and low-temperature brittleness, and particularly relates to a high-strength steel sheet exhibiting excellent workability and low-temperature brittleness in a tensile strength region of 1180 MPa or higher, and a method for producing the same. Background technique [0002] In order to achieve lower fuel consumption of automobiles and transport aircraft, it is desired to reduce the weight of automobiles and transport aircraft. For example, in order to reduce the weight, it is effective to use a high-strength steel plate and reduce the thickness of the plate. In addition, automobiles are particularly required for crash safety, and structural members such as pillars, and reinforcement members such as bumpers and crash beams are also required to be further strengthened. However, if the strength of the steel sheet is increased, the ductility deteriorates, so the workabilit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D8/02
CPCC21D9/46C22C38/14C22C38/002C22C38/005C22C38/12C22C38/04C21D2211/005C21D1/20C21D2211/002C21D8/0463C21D2211/008C22C38/06C22C38/02C21D8/02C21D8/0447C22C38/08C22C38/16C21D8/0473C22C38/001C22C38/18C22C38/00
Inventor 水田纱江二村裕一内海幸博
Owner KOBE STEEL LTD
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