900MPa热轧板Q-P-T工艺及其工程可行性的研究

 基于合金设计制备出2种低合金试验热轧板钢，在采用水淬＋盐浴回火的淬火-分配-回火（Q-P-T）工艺处理后，达到了屈服强度900MPa和伸长率15％的设计指标，为后期自行设计的单道次穿水淬火冷却装置用于热轧板的Q-P-T工艺工程可行性的研究奠定了基础。X射线衍射、扫描电镜和透射电镜的微观组织分析表明:与传统的淬火回火（Q&T）工艺相比，Q-P-T先进高强度钢中位错型板条马氏体基体及其内弥散分布的合金碳化物贡献于高的强度，板条马氏体间的薄片状奥氏体贡献于优良的塑性。此外，还进一步探讨了Q-P-T工艺中残余奥氏体的作用和多道次穿水淬火冷却装置用于不同厚度热轧板在线Q-P-T处理的可行性。

Quenching-Partitioning-Tempering Process and Its Engineering Feasibility of 900 MPa Grade Hot-Rolled Plate

Two kinds of experimental low alloy steels were prepared based on composition design.Following Quenching-Partitioning-Tempering(Q-P-T) process with the combination of water quenching plus tempering in salt bath,both the steels exhibited high yield strength of over 900 MPa combined with good elongation of above 15%,which would be the basis of self-designed the single-cycle passing underwater quenching equipment applied in Q-P-T process of hot-rolled plate for engineering feasibility.Microstructure characterization indicates that for Q-P-T steels,high strength is attributed to dislocation-type lath martensite matrix and dispersive distributed alloying-carbides in martensite matrix,while relatively high elongation results from flake-like retained austenite between martensite laths,comparing with the steels treated by conditional Quenching & Tempering(Q&T) process.In addition,the role of retained austenite in Q-P-T steels and the feasibility of online Q-P-T process treated by multi-cycle passing underwater quenching equipment for different hot-rolled plates in thickness were discussed.