Hot-rolling phase change induction plasticity steel with 750MPa-level extension strength and preparation method thereof

Abstract

The invention discloses a hot rolled transformation induced plasticity steel of 750MPa in tensile strength and the manufacture method which comprises the following procedures of 1) smelting, casting and blocking, the mass percentage compositions are: 0.08 to 0.20 percent of C, no more than 0.8 percent of Si, 0.5 to 2.0 percent of Mn, 0.8 to 2.5 percent of Al, no more than 0.03 percent of Nb, no more than 0.010 percent of N, no more than 0.020 percent of P, no more than 0.008 percent of S, 0.001 to 0.005 percent of Ca and the balance iron. 2) The blooms are heated to between 1150 and 1250 DEG C; keep the temperature and the holding time is in proportion to thickness 1 to 1.5min / mm; 3) Rolling: deformation occurs between the temperature ranges for austenite recrystallization, one pass or multi passes are adopted and the blooms are rolled into inner slabs. When deformation occurs between the temperature ranges lower than the Tnr temperature without austenite recrystallization but higher than Ar3 transformation point, blooms are rolled into steel plates of final thickness, and the finishing rolling temperature 800 to 880 DEG C.4) cooling. The invention has economical components, lower silicon contents, no Cr, Ni, Mo or other noble metal alloy elements, simple and applicable hot rolling technique, and steel slates of good surface quality, high strength and good plasticity.

Description

technical field [0001] The invention relates to a method for manufacturing iron and steel materials, in particular to a hot-rolled transformation-induced plasticity steel (TRIP) with a tensile strength of 750 MPa and a method for manufacturing the same. Background technique [0002] There are many varieties of automotive steel. Traditional low-strength steel (LSS) and high-strength steel (HSS) mainly include interstitial-free steel (IF), high-strength interstitial-free steel (IF-HS), ordinary carbon mild steel (MILD), and isotropic steel ( IS), bake-hardening steel (BH), carbon-manganese steel (C-Mn) and low-alloy high-strength steel (HSLA), dual-phase steel (DP), transformation-induced plasticity steel (TRIP) and other three types of parts Low strength grade varieties. With the development of the automobile industry, the requirements for vehicle safety are getting higher and higher, and the weight of vehicles is also required to be lighter and lighter to improve fuel econ...

AI Technical Summary

Problems solved by technology

Although this component is an economical component system, but the silicon content is high, it is easy to produce sticky and thick red oxide scale during the heating process, it is not easy to descale, and it is easy to press into the steel plate during rolling, resulting in poor surface quality

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