Low-carbon, low-silicon, cold-rolled and hot-galvanized dual-phase steel for extra-deep drawing and preparation method thereof

Abstract

The invention relates to low-carbon, low-silicon, cold-rolled and hot-galvanized dual-phase steel for extra-deep drawing and a preparation method thereof. The dual-phase steel comprises chemical components in percentages by mass as follows: 0.035%-0.045% of C, 0.03%-0.05% of Si, 1.3%-1.75% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.008% of S, smaller than or equal to 0.075% of Al, 0.5%-0.68% of Cr, 0.35%-0.5% of Mo and the balance of Fe and unavoidable impurities, wherein the content of P, S and Al is not 0, texture in the {111}//RD direction in microstructures of the dual-phase steel occupies more than 90 vol.%, the main microstructures adopt ferrite and martensite structures, the tension strength of the dual-phase steel ranges from 485-600 MPa, the elongation is higher than or equal to 32%, and an r value is 2-2.2. The dual-phase steel is matched with the corresponding preparation method. By means of the invention, certain quantity of Cr and Mo elements are added into the low-carbon dual-phase steel, a texture pre-treatment process is adopted, so that the deep drawability of a material is improved remarkably under certain strength condition, and the hot galvanizing performance of the material is improved sufficiently.

Description

technical field [0001] The invention belongs to the field of metal materials, and mainly relates to the preparation of a high-strength, ultra-deep drawn ferrite plus martensitic cold-rolled hot-dip galvanized dual-phase steel, adding Cr and Mo elements to the low-carbon steel, and adopting weaving The structural pretreatment process makes the material greatly improve its deep drawing performance under the condition of certain strength, and at the same time controls the Si content ≤ 0.05% (mass percentage), which fully improves the hot-dip galvanizing performance of the material. Background technique [0002] Cold-rolled dual-phase steel has attracted more and more attention in modern automotive steel because of its high strength, high elongation, high work hardening index and continuous yield. Traditional dual-phase steel is mainly used in reinforcements of automotive products, such as bumpers, profiles, and brackets. In order to reduce the weight of the vehicle to a greater...

AI Technical Summary

Problems solved by technology

However, due to the existence of some interstitial atoms, especially solid solution carbon, it will prevent the development of {111} direction texture during the recrystallization process, and accelerate the development of other textures such as {100}, so for general low carbon steel in After annealing, it is easy to form Gauss texture or brass texture, which are not conducive to the deep drawing performance of the material