Cr alloying steel without yield platform and preparation method thereof

Abstract

The invention discloses Cr alloying steel without a yield platform. The Cr alloying steel comprises, by mass, 0.03-0.3% of C, 1.0-9.0% of Cr, 0.01-2.0% of Mn, 0.01-2.0% of Al, 0.01-2.0% of Si, less than or equal to 0.02% of P, less than or equal to 0.02% of S, the balance being Fe and inevitable impurities; and the sum of the weight percentages of Al and Si is greater than or equal to 1.5%. A casting blank is obtained after molten steel smelting, and a hot-rolled coil with good plasticity can be directly used after the casting blank is heated and hot-rolled; austenite with moderate stability is obtained after annealing the hot rolled coil, and the preparation of a high-performance steel plate is finished; and a hot-rolled plate can also be subjected to on-line or off-line heat treatment, the hot-rolled plate is austenitized or partially austenitized by a heating furnace and then cooled to room temperature, the hot-rolled plate is heated and then annealed or directly annealed to obtainthe austenite with moderate stability, and the preparation of the high-performance hot-rolled plate is finished. According to the preparation method, the hot-rolled coil can be subjected to cold rolling again so as to obtain a cold-rolled steel plate with the required performance.

Description

technical field [0001] The invention relates to a Cr alloyed steel with no yield platform and a preparation method thereof, belonging to the technical fields of steel for automobiles and steel for structures. Background technique [0002] Because cold-rolled medium-manganese steel has both good strength and shape, it has received more and more attention in the field of steel for car bodies. However, common cold-rolled medium-manganese steel generally has a long yield plateau and relatively obvious dynamic strain aging after annealing, and these phenomena are unfavorable to the surface quality of the formed automobile sheet. [0003] At present, there are mainly two ways to overcome the yield plateau of cold-rolled medium manganese steel. One is to control the cold rolling reduction to be less than 30%, so that the structure after cold rolling is as similar as possible to the hot rolling structure, that is, the distortion in the structure after cold rolling is controlled as ...

AI Technical Summary

Problems solved by technology

The first method requires a small cold rolling reduction and has low operability

For the second method, since the Mn content in the medium manganese steel is relatively high, the addition of Al must be more than 3% to obtain δ-ferrite. Such a high Al content is difficult to carry out continuous casting smoothly. Therefore, the second method is not very operable under the existing composition system

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