Q-P-T工艺对20SiMn2MoV钢组织与性能的影响

Influence of quenching-partitioning-tempering process on microstructure and properties of 20SiMn2MoV steel

采用Q-P-T工艺对20SiMn2MoV钢进行热处理，利用扫描电镜、透射电镜研究其微观组织，使用XRD分析残留奥氏体的含量，并通过拉伸试验、冲击试验研究了Q-P-T工艺对钢力学性能的影响。结果表明，20SiMn2MoV钢经Q-P-T处理获得了板条马氏体＋残留奥氏体＋弥散析出碳化物的组织，残留奥氏体含量为4％～7％。淬火介质温度越高，残留奥氏体含量越高，钢的塑性、冲击韧性越好。碳分配时间应适中，过短则奥氏体稳定化不够，过长则发生碳化物析出及残留奥氏体分解。当淬火介质温度为90℃，碳分配60s时，钢的抗拉强度为1344MPa，伸长率达18．8％，强塑积为25267MPa·％，具有优良的强塑性匹配。

Effects of quenching-partitioning-tempering process on mierostructure and mechanical properties of a 20SiMn2MoV steel were studied. The microstructure of the steel was observed by means of scanning electron microscopy and transmission electron microscopy. The volume fraction of retained austenite was studied by X-ray diffraction, tensile and impact tests were carried out to analyze the mechanical properties of the steel. According to the experimental results, the mierostructure, lath martensite with retained austenite film and carbides precipitated in martensite matrix, is obtained. The volume fraction of retained austenite is between 4% and 7%. The higher quench medium temperature, the higher percentage of retained austenite and better performance of ductility and toughness of the steel. It is important to choose proper partitioning-tempering duration. Enough partitioning of carbon is essential for the stabilizing of austenite while excessive holding time leads to the precipitation of carbides and decomposition of austenite. The best mechanical properties of the steel are MPa ultimate tensile strength of 1344 MPa with 18.8% total elongation, and the product of strength and elongation is 25267 MPa% , which are obtained in 90 ℃ quenching medium and 60 s partitioning-tempering duration.