900MPa-grade hot-rolled complex-phase steel and production method thereof

Abstract

The invention relates to the technical field of hot-rolled complex-phase steel, in particular to 900MPa-grade hot-rolled complex-phase steel and a production method thereof. The 900MPa-grade hot-rolled complex-phase steel comprises the following components in percentage by weight: 0.070%-0.158% of C, 0.08%-0.85% of Si, 1.15%-2.50% of Mn, 0.10%-0.30% of Al, 0.10%-0.75% of Cr, 0.08%-0.65% of Mo, 0.0020%-0.0050% of B, 0.025%-0.070% of Nb and / or 0.030%-0.155% of V, less than or equal to 0.020% of P, less than or equal to 0.007% of S and the balance Fe and inevitable impurities. The production method comprises the following steps that (1) a continuous casting sheet billet with the thickness of 80-300mm is heated in a heating furnace, and the temperature is kept for 5-6 hours; (2) the initial rolling temperature of rough rolling is not higher than 1080 DEG C, the thickness of an intermediate billet is 25-50 mm, the finish rolling temperature is controlled, the thickness of a finished product is 2.0-5.0 mm, and the total reduction rate is larger than or equal to 80%; (3) after finish rolling, front-section rapid continuous laminar cooling is adopted, and coiling is conducted; and (4) after being coiled, the steel plate immediately enters a slow cooling cover to be slowly cooled to 140 DEG C or below, the slow cooling speed is not larger than 13 DEG C / h, and a steel coil is taken out and air-cooled to the room temperature. The 900MPa-grade hot-rolled complex-phase steel has ultrahigh strength and good formability, is suitable for manufacturing automobile components such as structural pieces, reinforcement pieces and safety pieces, and is particularly suitable for manufacturing bumpers and B pillar reinforcement pieces.

Description

Technical field [0001] The present invention relates to the technical field of hot rolling reciprocating steel, and more particularly to a 900 MPa-level hot rolling reciprocating steel and its production methods. Background technique [0002] The new generation of automotive trends is energy saving, consumption, environmental protection and security. Advanced high-strength steel is widely used in automotive manufacturing purposes to achieve its lightweight goals. The R & D and application of advanced high and high strong steel is the leading direction of future material technology development. Advanced high strength steel is mainly composed of five major categories, low alloys, high-strength steel, double phase steel, phase steel, phase-induced plastic steel, Martensg steel, etc., its strength ranges from 500 ~ 1600MPa, both high strength and better Formability, in automotive manufacturing applications, high weight loss potential, high collision absorption energy, high moldabilit...

AI Technical Summary

Problems solved by technology

[0004] The existing hot-rolled multiphase steel has low yield strength, low tensile strength, low elongation, and high yield ratio, which do not meet the requirements of high-strength formed automotive structural parts

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