Martensitic steel with delayed fracture resistance and manufacturing method

一种耐延迟断裂、马氏体钢的技术，应用在耐延迟断裂性的完全马氏体级别钢领域，能够解决没有教导耐延迟断裂、耐延迟断裂性没有记载等问题

Active Publication Date: 2016-11-23
ARCELORMITTAL INVESTIGACION Y DESARROLLO SL
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the application is silent in relation to delayed fracture resistance, the application does not teach how to obtain delayed fracture resistant steel

Method used

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  • Martensitic steel with delayed fracture resistance and manufacturing method
  • Martensitic steel with delayed fracture resistance and manufacturing method
  • Martensitic steel with delayed fracture resistance and manufacturing method

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Embodiment Construction

[0054] In order to obtain the martensitic steel sheet according to the invention, the chemical composition as well as the production parameters are important in order to achieve all objectives and obtain excellent delayed fracture resistance. Nickel content below 0.5% is required to reduce hydrogen embrittlement, carbon content between 0.3% and 0.5% is required for tensile properties and Si content above 0.5% is also required for improved hydrogen embrittlement resistance.

[0055] The following chemical constituent elements are given in weight percent.

[0056]Regarding carbon: increasing the content above 0.5 wt% increases the amount of grain boundary carbides, which is one of the main causes of deterioration in delayed fracture resistance of steel. However, a carbon content of at least 0.30 wt% is required to achieve the target steel strength - ie, a tensile strength of 1700 MPa and a yield strength of 1300 MPa. Therefore, the carbon content should be limited within the ra...

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Abstract

A cold rolled and annealed martensitic steel sheet is provided. The steel sheet includes by weight percent, 0.30 greater than or equal to C smaller than or equal to 0.5%, 0.2 greater than or equal to Mn smaller than or equal to 1.5%, 0.5 greater than or equal to Si smaller than or equal to 3.0%, 0.02 greater than or equal to Ti smaller than or equal to 0.05%, 0.001 greater than or equal to N smaller than or equal to 0.008%, 0.0010 greater than or equal to B smaller than or equal to 0.0030%, 0.0 greater than or equal to Nb smaller than or equal to 0.1%, 0.2 greater than or equal to Cr smaller than or equal to 2.0%, P smaller than or equal to 0.02%, S smaller than or equal to 0.005%, Al smaller than or equal to 1%, Mo smaller than or equal to 1% and Ni smaller than or equal to 0.5%. The remainder of the composition includes iron and unavoidable impurities resulting from melting. The microstructure is 100% martensitic and a prior austenite grain size is lower than 20(mu)m. The steel sheet has a delayed fracture resistance of at least 24 hours during an acid immersion U-bend test. A method, part, structural member and vehicle are also provided.

Description

technical field [0001] The present invention relates to a martensitic steel for vehicles, which exhibits excellent delayed fracture resistance. This steel is intended to be used as a structural member and reinforcement material mainly for automobiles. The invention also relates to a method of producing a fully martensitic grade of steel with excellent delayed fracture resistance. Background technique [0002] Steel parts of automobiles are often exposed to environments that can form and absorb atomic hydrogen. The absorbed hydrogen may be in addition to hydrogen that has been absorbed during part fabrication. Hydrogen can cause detrimental effects in steel by reducing the failure stress of the steel, limiting ductility and toughness, or even accelerating crack growth in the steel. Failure of steel due to hydrogen attack may occur instantaneously upon loading or after a delayed period of time. This behavior makes failure due to hydrogen embrittlement exceptionally difficu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/40
CPCC22C38/40C22C38/001C22C38/02C22C38/04C22C38/06C22C38/26C22C38/28C22C38/32C22C38/34C21D8/0226C21D8/0236C21D8/0273C21D2211/008C21D8/0205C21D8/021C21D8/0263C21D8/0278C22C38/002C22C38/08C22C38/12C22C38/14C22C38/16C21D9/46C21D8/02C22C38/54
Inventor 宋荣杰纳拉扬·波托里妮娜·方斯泰因
Owner ARCELORMITTAL INVESTIGACION Y DESARROLLO SL
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