Micro-carbon aluminum-killed steel with low yield ratio and good deep drawing property and preparation method thereof

Abstract

The invention provides micro-carbon aluminum-killed steel with low yield ratio and good deep drawing property and a preparation method thereof, belonging to the technical field of automobile steel. The micro-carbon aluminum-killed steel is obtained by adding 0.001-0.008% of B on the basis of the components of the micro-carbon aluminum-killed steel and controlling the hot rolling and coiling temperature and the annealing temperature. The micro-carbon aluminum-killed steel has the following components in percentage by mass: 0.01-0.06% of C, not more than 0.5% of Si, not more than 0.4% of Mn, not more than 0.02% of P, not more than 0.02% of S, not more than 0.07% of Al, not more than 0.06% of N, 0.001-0.008% of B and the balance Fe and inevitable impurities. The element B in the steel is used for fixing N in the steel and is beneficial to obtaining coarse ferrite grains after annealing, thereby ensuring the annealed sheet steel to have low yield strength and high r value. The invention has the advantage of obtaining the micro-carbon aluminum-killed steel with yield strength being not more than 130MPa, yield ratio being not more than 0.39, r value being not less than 1.5 and good deep drawing property by hot rolling and low temperature coiling, cold rolling and continuous annealing.

Description

technical field [0001] The invention belongs to the technical field of steel for automobiles, and in particular provides a micro-carbon aluminum-killed steel with a low yield ratio and good deep drawability and a preparation method thereof. Background technique [0002] The micro-carbon deep-drawing steel plate is developed on the basis of low-carbon aluminum-killed steel. Carbon is the most common strengthening element in steel, which increases the strength of steel and decreases its plasticity. Reducing the carbon content of low-carbon aluminum-killed steel to micro-carbon is the most effective way to improve formability. When the carbon content drops below 0.02%, the spacing of carbides in the steel increases, which is conducive to the formation of <111> / / ND texture and increases the r value. Due to the low carbon and the decrease of the solid solution carbon content in the steel, it also solves the problem of aging. [0003] When the continuous annealing process...

AI Technical Summary

Problems solved by technology

Therefore, when the steel with a certain amount of microalloying element B is hot-rolled, B can preferentially combine with free nitrogen in the steel in the high-temperature austenite to form coarse BN particles, which reduces the mass fraction of solid-dissolved nitrogen in the steel and suppresses the fine particles of AlN. The precipitation of the ferrite structure reduces the fine grain strengthening of the ferrite structure and the precipitation strengthening of AlN, thereby reducing the strength of the material

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