A kind of ultra-high strength cold-rolled phase transformation induced plasticity steel and its preparation method

Abstract

The invention discloses ultrahigh-strength cold-rolled transformation-induced plasticity steel and a manufacturing method thereof. The ultrahigh-strength cold-rolled transformation-induced plasticitysteel is prepared from 0.5-1.0% of C, 0.3-1.0% of Si, 1.0-3.0% of Mn, 0.03-0.12% of P, less than or equal to 0.03% of S, 0.8-2.0% of Al, one or more of 0.05-0.3% of V, 0.05-0.3% of Ti, 0.05-0.3% of Nb, 0.1-0.5% of Cr and 0.05-0.3% of Mo, and the balance Fe and inevitable impurities. The initial rolling temperature of hot rolling is 1,000-1,150 DEG C, the final rolling temperature of hot rolling is850-1,000 DEG C, and the coiling temperature is 400-700 DEG C; the reduction rate of cold rolling is 40-80%; the continuous annealing temperature is 700-900 DEG C, and the annealing time is 120-400 s; the cooling rate is 15-60 DEG C per second; the aging temperature is 300-450 DEG C; the aging time is 300-800 s; and the temperature is decreased to the room temperature at the rate of 10-30 DEG C per second. Steel plates have ultrahigh strength and good ductility.

Description

technical field [0001] The invention belongs to the field of steel manufacturing for automobiles, and in particular relates to a cold-rolled phase-change-induced plasticity steel with ultra-high strength and high elongation and a preparation method thereof. Background technique [0002] At present, with the improvement of energy saving, emission reduction and safety performance requirements, automotive steel is developing towards higher strength and higher elongation. The elongation of traditional automotive steel decreases with the increase of strength, especially when the tensile strength of the steel plate exceeds 1470MPa, the elongation decreases more obviously. [0003] Patent CN102181788A discloses an ultra-high-strength steel with a yield strength of 1100-1200MPa and its production method. When the tensile strength reaches 1250-1340MPa, the elongation is only 11%-13.5%, which is difficult to meet the strength requirements of automobile factories. [0004] Patent US 2...

AI Technical Summary

Problems solved by technology

The disadvantage is that the formability is low and it is difficult to punch out complex parts

[0006] Patent CN 102134680 A discloses a super high-strength steel with a yield strength of 960MPa and its production method. The steel grade has a yield strength of more than 960MPa, a tensile strength of more than 1000MPa, and an elongation of 12.5% ​​to 15.5%. It is difficult to meet the strength requirements of automobile factories

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