Heat-hardened steel with excellent crashworthiness and method for manufacturing heat-hardenable parts using same

Abstract

Disclosed are heat-hardened steel with excellent crashworthiness and a method for manufacturing heat-hardenable parts using the same. The heat-hardened steel according to the invention comprises, based on wt%, C: 0.12-0.8 %, Cr : 0.01-2 %, Mo: 0.2 % or less, B: 0.0005-0.08 %, Ca: 0.01 or less, Sb: 1.0 % or less, and Ti and / or Nb: 0.2 %, and the reminder being Fe and inevitable impurities. In addition, the heat-hardened steel satisfies any one of following conditions i)-iv), wherein condition i) comprises Si: 0.5-3 %, Mn: 1-10 % and Al: 0.05-2 %, condition ii) comprises Si: 1 % or less, Mn: 0.5-5 %, Al: 0.1-2.5 %, and Ni: 0.01-8 %, condition iii) comprises Si: 0.5-3 %, Mn: 1-10 %, Al: 0.1 % or less, and Ni: 0.01-8 %, and condition iv) comprises Si: 0.5-3 %, Mn: 1-10 %, Al: 0.1-2.5 %, and Ni: 0.01-8 %.

Description

technical field [0001] The present invention relates to a technique for manufacturing a high-strength member using heat-treated hardened steel, and more particularly, to a heat-treated hardened steel having high strength and crashworthiness after heat treatment and a method for manufacturing a heat-treated hardened member using the same. Background technique [0002] Recently, lightweight and high-strength automotive components have been developed to improve fuel efficiency. [0003] Recently, hot stamping has been developed with the development of technology for manufacturing automotive components. Hot stamping is the process of manufacturing high-strength components by quenching to form a martensitic microstructure once a material with a tensile strength of about 500 MPa is heated to about 900°C to form the desired shape. Hot stamping can be used to produce high-strength components with a tensile strength above 1000MPa. [0004] Steel for hot stamping contains C: 0.23%; ...

AI Technical Summary

Problems solved by technology

[0007] However, the components produced by this process have the disadvantage of having a low elongation of 6% to 7% due to the close to full martensitic microstructure which is conducive to ensuring high strength

[0008] When an external impact is applied to the above member, this low elongation leads to brittle fracture of the member due to insufficient absorption of the impact

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