Anti-delayed-cracking martensite type ultra-high strength cold-rolled steel strip and production method thereof

Abstract

The invention relates to an anti-delayed-cracking martensite type ultra-high strength cold-rolled steel strip and a production method thereof, wherein the chemical components comprise, by weight, 0.10-0.24% of C, 0.5-1.0% of Si and Al, 1.4-2.0% of Mn, 0.05-0.25% of W, 0.04-0.12% of Mo, less than or equal to 0.012% of P, less than or equal to 0.003% of S, less than or equal to 0.003% of N, 0.05-0.3% of Al, 0.001-0.003% of Ca, one or two selected from 0.02-0.04% of Ti and 0.02-0.04% of Nb, and the balance of Fe and inevitable impurities. According to the present invention, the steel has characteristics of excellent cold bending performance and good delayed-cracking resistance, has the strength of more than 1180 MPa, cannot produce delayed cracking in the case of the preset stress of more than one time tensile strength after being soaked in a 1 mol / L hydrochloric acid of for more than 300 h, and is especially suitable for the manufacture of vehicle safety structure members.

Description

technical field [0001] The invention relates to a martensitic ultra-high-strength cold-rolled steel strip resistant to delayed cracking and a manufacturing method thereof. Background technique [0002] The automotive industry requires the use of higher strength steel plates for weight reduction and safety needs. Among them, ultra-high-strength steel with a tensile strength of 1000Mpa and above has great potential for weight reduction and safety performance, and can be used in the manufacture of safety parts, reinforcements and structural parts. However, high-strength steel above 1000MPa naturally has the characteristics of stress corrosion cracking (delayed cracking), that is, the process of slow cracking under the action of stress and corrosive media, which causes considerable trouble to the application and greatly limits the performance of ultra-high-strength steel. steel application. The so-called delayed cracking refers to the problem that cracking does not occur when ...

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