研究了经一步淬火C配分(Q&P)工艺处理的双马氏体实验钢的微观组织与力学性能, 并与经直接淬火及淬火回火(Q&T)工艺处理的实验钢进行对比, 初步探讨了一步Q&P工艺对材料微观组织和力学性能的影响规律. 结果表明, 显微组织主要由板条马氏体、片状马氏体和板条间薄膜状残余奥氏体组成, 且随着保温时间的延长, 片状马氏体含量先增加后减小, 残余奥氏体含量逐渐增大且趋于稳定. 与传统的直接淬火及Q&T工艺相比, 经一步 Q&P工艺处理后的实验钢具有良好的综合力学性能, 即具备高强度的同时也具备良好的塑性, 其强塑积、抗拉强度和延伸率分别可达21774.2 MPa%, 1442 MPa和15.1%, 且随着保温时间的延长, 抗拉强度逐渐减小, 延伸率逐渐增大且趋于稳定.

In accordance with the demand for reduced fuel consumption and CO2 emissions in automobiles, and with the increasing high demand for vehicle lightweight and safety, advanced high- strength steels (AHSS) have received more attentions in recent years. The recent trend for the development of AHSS has been concentrated on the complex microstructure with multiphase. Quenching and partitioning (Q&P) steel with carbon-enriched austenite within martensitic matrix as a competitive candidate of AHSS have been developed widely. It has high strength and good ductility depending on the multiphase microstructure. Therefore, the relationship of the mechanical property and the microstructure of the Q&P steels should be studied in detail. In the present work, the microstructure characterization and mechanical properties of the experimental steel treated by one step Q&P process were investigated, as well as the direct quenching and Q&T processes. The results show that the microstructure of the steel treated by one step Q&P process mainly consists of lath martensite, plate martensite and residual austenite films between martensite laths. With a increase in the holding time, the fraction of the plate martensite firstly increases and then reduces, while that of the retained austenite firstly increases and then becomes constant. The combination of strength and elongation of the steel processed by one step Q&P is much better than the one processed by the other two, that is to say, the former one can possess good strength and ductility at the same time. The product of tensile strength and elongation, the tensile strength and the elongation can achieve 21774.2 MPa·%, 1442 MPa and 15.1%, respectively. Along with the holding time increasing, tensile strength decreases but elongation rises and finally be stable.