Micro-carbon high-strength deep-punching steel with niobium and chromium, and preparation method thereof

Abstract

The invention belongs to the technical field of alloy, and particularly relates to micro-carbon high-strength deep-punching steel with niobium and chromium, and a preparation method thereof. The micro-carbon high-strength deep-punching steel with niobium and chromium comprises the following ingredients, by mass, 0.01% to 0.03% of C, 0.1% to 0.5% of Si, 1.5% to 2.0% of Mn, 0.01% to 0.06% of P, equal to or smaller than 0.015% of S, 0.1% to 0.5% of Cr, 0.01% to 0.05% of Nb, smaller than 0.01% of N, the balance Fe and unavoidable impurities, wherein the molar ratio of Nb to C ranges from 0.05 to 1to 0.3 to 1, and the molar ratio of Cr to C ranges from 1 to 1 to 3 to 1. According to the micro-carbon high-strength deep-punching steel with niobium and chromium, the tensile strength is 510 MPa, the elongation is 29.1%, the strain hardening index is 0.22, the plastic strain ratio is 1.5, and the good strength and the good deep punching performance are achieved as well.

Description

technical field [0001] The invention belongs to the technical field of alloys, in particular to a micro-carbon high-strength deep-drawing steel containing niobium and chromium and a preparation method thereof. Background technique [0002] The development trend of the new generation of automobiles is safety, environmental protection, energy saving and emission reduction. Therefore, the car must rely on reducing its own weight to reduce fuel consumption and reduce emissions under the premise of ensuring safety. Ferritic and martensitic dual-phase (Dual Phase, DP) steel has a series of excellent mechanical properties, such as high strength, high elongation and high work hardening index, etc., and has attracted more and more attention in modern automotive steel. At present, the research and application of DP steel has developed from 590MPa level to 1180MPa level, and the elongation rate has reached 12%. However, in the traditional dual-phase structure, the existence of a rela...

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Problems solved by technology

[0004] Chinese invention patent CN102517492A discloses a preparation process of ultra-deep drawing dual-phase steel, by adding alloy element V, adding sub-temperature annealing before continuous annealing to improve the initial structure of dual-phase steel, so as to obtain suitable martensite and structure structure; but its process control is difficult, the sub-temperature range is difficult to control, and the strength needs to be improved

[0005] Chinese invention patent ZL201110258213.0 mentions the use of alloying elements Cr and Mo to improve deep drawing performance, and give full play to the effects of low-temperature precipitation of carbon fixation and high-temperature re-dissolution of such elements, which can not only develop the matrix texture, but also can be used in the annealing process. Ensure a certain carbon content to form a martensitic phase; however, fine and dispersed precipitation is unfavorable to the optimization of the matrix texture, especially in the recrystallization process, this adverse effect is to reduce the strength of the matrix texture

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