610MPa automobile girder steel and production method thereof

Abstract

The invention discloses a 610MPa automobile girder steel, and the weight percentage (wt%) of the chemical composition of the steel is as follows: C: 0.08 to 0.12; Si: 0.10 to 0.30; Mn: 1.40 to 1.60; P: less than or equal to 0.010; S: less than or equal to 0.005; Nb: 0.040 to 0.060; V: 0.020 to 0.030; Ti: 0.010 to 0.030; Al: 0.030 to 0.060; Ca: tiny amount; and the rest is iron and residual trace impurities. The invention also discloses a production method for the 610MPa automobile girder steel, which adopts a 2250mm hot rolling line, and a continuously cast slab is heated to 1200 DEG C to 1250 DEG C; after rough rolling, the temperature is 1000 DEG C to 1050 DEG C, the continuously cast slab enters a finishing mill via a heat cover and is rolled, the finish rolling temperature is 820 DEG C to 880 DEG C, and the rolled steel coil is rapidly cooled to 530 DEG C to 580 DEG C by way of laminar cooling, and is then coiled. Since the chemical composition and the production technique are adopted, the tensile strength of an automobile girder is larger than 610MPa, the yield strength is larger than 500MPa, the specific elongation is larger than 20 percent, minus 60 DEG C longitudinal impact energy AKV is larger than 70J, and the automobile girder has excellent cold formability and high fatigue strength. The product is applicable to heavy-duty automobile members such as side members and cross members, which are produced by cold-roll forming and stamping forming techniques.

Description

technical field [0001] The invention relates to the technical field of continuous hot-rolled metal strips, in particular to a steel material for high-strength automotive structural parts such as automotive longitudinal beams and beams and a manufacturing method thereof. Background technique [0002] Automobile girder is the most important safety component of the vehicle, and its material must have comprehensive properties such as good forming, welding, and fatigue resistance while requiring high strength. At present, the materials used in domestic commercial vehicle beams are mostly 510MPa and 550MPa beam plates. In the invention patent K with the application number CN200510024059.5, a kind of steel for elongated automobile beams and its manufacturing method is disclosed. The tensile strength can reach 580MPa by adding Nb, V, Ti multi-element micro-alloying elements, and the scope of application is only for manufacturing automobile beams by rolling process. The invention pa...

AI Technical Summary

Problems solved by technology

For general high-strength steel, when the strength reaches 600MPa, the plasticity is significantly reduced, and it is difficult to meet the forming process requirements of different automobile beam users.

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