Economical Nb-containing cold-rolling medium manganese steel and preparation method thereof

Abstract

The invention discloses economical Nb-containing cold-rolling medium manganese steel and a preparation method thereof. The economical Nb-containing cold-rolling medium manganese steel is prepared fromthe following chemical components in percentage by mass: 0.15 to 0.20 percent of C, less than or equal to 0.20 percent of Si, 3.8 to 4.2 percent of Mn, 0.10 to 0.20 percent of Nb, less than or equalto 0.01 percent of P, less than or equal to 0.01 percent of S, and the balance Fe. According to the economical Nb-containing cold-rolling medium manganese steel and the preparation method thereof provided by the invention, the process parameters are reasonably controlled, no any noble metal element is added on the basis of traditional medium manganese steel, meanwhile, the Mn content is reduced, so that on one hand, the smelting and continuous casting performances are improved, and the occurrence of segregation and cracks is reduced; on the other hand, through the reasonable matching of the reduction of the Mn content and a hot rolling process, the deformation resistance during cold rolling is reduced, so that the processes such as intermediate annealing are reduced, and the technologicalprocess is shortened; and a large number of metastable austenite, ultra-fine ferrite and carbide structures are obtained through a reversal transformation annealing process, so that the strength and the plasticity of the steel are improved, and the development demands of high strength and plasticity, good welding performance, resource conservation, cost reduction and the like of the steel for an automobile are met.

Description

technical field [0001] The invention relates to the technical field of cold-rolled steel for automobiles, in particular to an economical Nb-containing cold-rolled medium-manganese steel and a preparation method thereof. Background technique [0002] With the development of society, people put forward higher requirements and standards for the collision safety, energy saving effect and cost of automobile steel. First of all, the improvement of safety is mainly through the rational design of the body and the selection of materials with high impact energy absorption capacity; in addition, under the premise of ensuring the safety performance of the car, the lightweight of the car is an important way to achieve energy saving and cost reduction. Therefore, the future development of automotive steel should develop in the direction of high strength, high plasticity, low cost and easy processing. [0003] In recent years, the development of medium manganese steel satisfies the perfor...

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Problems solved by technology

Both of these patents have achieved a high-strength plastic product of 30-45GPa·%, but the heat treatment process is complicated, and the composition design with a high Mn content is not suitable for mass production of the process

[0006] The strength-plasticity product of the first generation of advanced high-strength steel is only 10-15GPa·%. In order to pursue a high strength-plasticity product, very high content of alloying elements is often used, or technological means that are difficult to achieve with existing equipment