A kind of cold-rolled dual-phase steel and preparation method thereof

Abstract

The invention provides a cold-rolled dual-phase steel and a preparation method thereof, comprising the following components in weight percent: C: 0.06% to 0.10%, Si: 0.3% to 0.6%, Mn: 2.2% to 2.6%, P: ≤ 0.02%, S: ≤0.02%, Alt: 0.03%~0.08%, Cr: 0.8‑1.1%, Nb: 0.03‑0.06%, Ti: 0.01‑0.03%, N≤0.005%, the balance is Fe and impurity elements . The tensile strength of the dual-phase steel of the present invention reaches 1000MPa level. In the composition design, Cr is used instead of Mo and trace Nb elements are added, which basically does not increase the cost of the alloy; by reducing the C content and tempering at low temperature in the annealing stage, the hardness of the martensite is improved. Reduce the hardness difference between the soft and hard two phases, thereby improving the hole expansion performance of the material. In addition, the yield strength of the material is increased.

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and in particular relates to a cold-rolled dual-phase steel and a preparation method thereof. Background technique [0002] With the increasingly stringent fuel standards of automobiles and the gradual advancement of lightweight body design, new automobile models have begun to use a higher proportion of advanced high-strength steel, especially high-strength steel with a tensile strength of more than 1000MPa and above has been applied more and more. In the past few years, the growth of the amount of advanced high-strength steel in each vehicle has been higher than expected. Although there are alternative automotive materials such as aluminum, magnesium, and carbon fiber, from the perspective of the entire life cycle of production, use, and scrap recycling, the steel’s It has the lowest carbon dioxide emission and has incomparable competitive advantages over other materials. It wil...

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