Hot-rolled TRIP steel with tensile strength being 900 MPa level and preparation method thereof

Abstract

The invention provides hot-rolled TRIP steel with tensile strength being the 900 MPa level and a preparation method thereof. The steel comprises, by chemical mass percentage, 0.10-0.30% of C, smallerthan or equal to 0.10% of Si, 4-8% of Mn, smaller than or equal to 0.01% of P, smaller than or equal to 0.008% of S, 1.0-2.0% of Al, smaller than or equal to 0.04% of Nb, smaller than or equal to 0.10% of V and the balance Fe and inevitable impurities. By means of control over chemical components, hot-rolling technology parameters and the heat treatment technology, after ferrite and austenite two-phase areas (Ac1-Ac3) are annealed, the finished product TRIP steel with the texture state being ferrite, bainite and residual austenite, by means of addition of micro alloy element Nb and V, C and Nin the steel can be fixed, the adverse influence of AlN to thermoplasticity is eliminated, and the refined crystalline strengthening and precipitation strength functions are played effectively. The rare earth element is added, and the functions of reducing alloy segregation and refining as-cast structure can be achieved. The tensile strength of the product is larger than or equal to 900 MPa, the ductility after breakage is larger than or equal to 25%, the product of strength and elongation can reach 25-30 GPa%, the requirements for the light weight, energy saving and consumption reducing of car industry are fully met, and the steel has good economy and application prospect.

Description

technical field

[0001] The invention belongs to the technical field of hot-rolled strip steel production technology, and in particular relates to a hot-rolled TRIP steel with a tensile strength of 900MPa and a preparation method thereof. Background technique

[0002] With the development trend of automobile lightweight, energy saving and safety improvement, high-strength steel has become the focus of steel material research in recent years and has been widely used in automobile manufacturing. However, in order to meet the forming conditions of body components, the elongation of high-strength steel must be guaranteed, so the strength level of high-strength steel used is limited, and some parts with complex shapes that require high strength can only be produced by welding after forming .

[0003] The TRIP steel with medium manganese content, that is, the phase transformation induced plasticity steel, induces the TRIP effect during deformation, so that the retained austenite f...

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