980-MPa-grade cold-rolled alloyed galvanized quenched partition steel and preparation method thereof

Abstract

The invention relates to 980-MPa-grade cold-rolled alloyed galvanized quenched partition steel and a preparation method thereof. The steel is prepared from the chemical components including, by weight, 0.1%-0.17% of C, 0.60%-1.0% of Si, 1.50%-2.50% of Mn, less than or equal to 0.05% of P, less than or equal to 0.05% of S, less than or equal to 0.05% of Als, one of Nb, Ti and V as well as the balance Fe and inevitable impurities; the content of Nb is less than or equal to 0.02%, the content of Ti is less than or equal to 0.02%, and the content of V is less than or equal to 0.05%; meanwhile, C+Si / 4 is less than or equal to 0.4%; a metallographic structure is a ferrite, tempered martensite and retained austenite structure, and the austenitizing temperature of the steel is lower than or equal to 840 DEG C. The production technology comprises the steps of smelting, hot continuous rolling, pickling cold rolling and alloying galvanization. Through alloy and technology design, the hole expansion rate of 60% or above is achieved with the low alloy cost, and the product has higher market competitiveness.

Description

Technical field [0001] The present invention relates to the field of automotive steel manufacturing techniques, and more particularly to a 980 MPa-level cold rolled alloying galvanized quenching distribution steel and a preparation method thereof. Background technique [0002] With the development of the automobile industry, automobile high-strength steel is in white car (referring to the body structure and coverage welding assembly, including front wing, door, hood, luggage cover, but not including accessories and decorative parts The application ratio on the paint body is gradually increased, and the intensity level has gradually increased. For example, the application ratio of 980MPa above the domestic car is not 3% in 2014, an increase of about 10%. At the same time, the application ratio of hot galvanized steel plates and alloying galvanized steel sheets is also continuously increased. [0003] Up to now, high-strength steel, 980MPA, including DP steel (double phase steel), ...

AI Technical Summary

Problems solved by technology

The technical solution adopts the technological idea of ​​reducing the hardness difference between soft and hard phases through bainite, and obtains mechanical properties with a yield strength of more than 700MPa, a tensile strength of more than 980MPa, an elongation after fracture of more than 12%, and a hole expansion rate of 25-32%. However, a large increase in the proportion of microalloying significantly increases the cost of the alloy, and at the same time, the inhomogeneity of its own bainite phase structure is not conducive to the uniform distribution of strain in the hole expansion stage.

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