A kind of 600mpa grade multi-phase steel with good flanging performance and its production method

Abstract

The invention relates to a 600 MPa grade multiphase steel with good flanging performance, and the 600 MPa grade multiphase steel with the good flanging performance comprises the compositions of, by weight, 0.060-0.100% of C, 0.060-0.400% of Si, 1.20-2.00% of Mn, 0.020% or less of P, 0.010% or less of S, 0.015-0.070% of Als, 0.15-0.35% of Cr, 0.010-0.035% of Ti, 0.010-0.035% of Nb and 0.006% or less of N; A production process comprises the steps that according to the composition setting, blank casting is conducted after conventional smelting is conducted; hot rolling process is performed; coldrolling process is performed; the blank casting is naturally cooled to room temperature, and the blank casting is waiting for used. Yield strength is 360 - 440 MPa, tensile strength is 600 ~ 700 MPa,elongation is 19% or above, the hole expansion rate is 45% or above. The microstructure of the 600 MPa grade multiphase steel is pearlite, bainite, ferrite, a small amount of martensite and residual austenite, thus it is ensured that the good forming performance, flanging performance and collision energy absorption performance are achieved while the high strength is achieved.

Description

technical field [0001] The invention relates to a steel for automobile safety structural parts and a production method thereof, which precisely belongs to the steel for automobile safety structural parts of 600MPa grade with good flanging performance and a production method. Background technique [0002] The automobile industry is a pillar industry in industrially developed countries, and it is also the largest user of steel companies. Under the requirements of energy saving, environmental protection, safety and sustainable development, high-strength and ultra-high-strength steels have become the mainstream of steel for automobile bodies, thus reaching the automotive industry. In order to develop high-strength steel plates for automobiles and promote the lightweight of automobiles, a large number of researches on related automobile lightweight projects have been started in the world in recent years. The common point of their research is to reduce the weight of automobiles. 2...

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Problems solved by technology

This document also does not involve the hole expansion rate data to evaluate the important flanging performance, and this invention is to quickly cool the steel to the bainite point after austenitization to undergo bainite isothermal phase transformation, and then quench it in water to The method of obtaining martensite at room temperature obtains ultra-high strength, so its strength is high, but its formability is poor, and problems such as cracking and severe springback of parts are prone to occur during the forming process. At the same time, it has relatively large limitations according to its production process , not suitable for industrial production

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