Quenched partitioned cold-rolled steel sheet with tensile strength of greater than 1180 MPa, and production method thereof

Abstract

The invention relates to a quenched partitioned cold-rolled steel sheet with tensile strength of greater than 1180 MPa, and a production method thereof. During annealing heating, a steel plate is partially austenitized, so the enrichment of carbon in an austenite structure is realized; the two-phase-region slow cooling is employed for adjusting the volume fractions of an austenite phase and a ferrite phase, carbon is further enriched in the austenite; then rapid cooling at a cooling rate of 30-40 DEG C/s is carried out to partially convert the austenite into martensite; then heating and heat preservation are carried out; and finally, air-cooling to room temperature is carried out to obtain a multi-phase structure of ferrite, martensite and metastable austenite. The invention has the advantages that the production method is used for batch production of the quenched partitioned cold-rolled steel sheet with the tensile strength of greater than 1180 MPa; the quenched partitioned cold-rolled steel sheet has simple chemical components, no elemental Nb or only a small amount of elemental Nb is added except C, Si and Mn, so smelting cost is low, and process control is simple; two-phase-region heating is employed for continuous annealing; rapid cooling requires a low cooling speed and has low requirements on the equipment capacity of a continuous-annealing unit is low; and the production method is simple.

Description

technical field [0001] The invention belongs to the field of cold-rolled automobile steel manufacturing, and in particular relates to an ultra-high-strength quenched and distributed steel plate for cold-rolled automobiles with a tensile strength greater than 1180 MPa and a production method. Background technique [0002] In recent years, with the improvement of the quality of life, the automobile industry has continued to develop rapidly, and the number of vehicles has increased year by year. While this trend has caused severe pressure on transportation, it has also brought a huge burden on energy and the ecological environment. Data show that every 10% reduction in vehicle weight can save energy consumption by 3% to 7%; the vehicle will be more stable due to the reduction in chassis mass; lightweight materials can absorb impact energy and improve collision safety. Therefore, automobile lightweight has become an inevitable trend. [0003] Advanced high-strength steel is an...

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Problems solved by technology

[0005] In the existing public literature: Wang Chenglin, Li Wei, Jin Xuejun published a new type of high silicon hot forming steel quenching-partition treatment and its properties [J]. Journal of Materials Heat Treatment, 2015 (05); Wan Decheng, Feng Yunli, Li The effect of isothermal temperature on the microstructure and properties of direct quenching and partitioning ultra-high strength steel published by Jie [J]. Thermal Processing Technology, 2015 (10); Zhou Yedong, Zhou Shu, Ding Chen, Zhang Jianwei, Li Hetian, Fang Jian published QP980 steel low temperature toughness Research on brittleness[J].Journal of Plastic Engineering,2015(03);Zuo Dungui,Yan Qi,Wang Li,Study on microstructure and properties of laser welded seam of ultra-high strength QP980 steel[J].Metal Processing (Hot Processing), 2015 (04); Zheng Debing, Liu Yifan, Wu Chunming, Yu Huanqing's research on the stamping stability of the third generation high-strength steel QP980 [J]. Mold In

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