一种新型高硅热成形钢的淬火-配分处理及其性能

Microstructure and mechanical properties of high silicon hot stamping steel treated by quenching-partitioning process

研究了不同温度和时间的淬火-配分(Q-P)处理工艺对新型高硅(Si含量为0.82 mass%)热成形钢组织与力学性能的影响,采用光学显微镜(OM)和扫描电镜(SEM)对试样的微观组织进行了观察。结果表明,材料为板条马氏体+残留奥氏体组织,存在较多的M/A岛。当淬火温度为260℃,配分300 s时,材料的强塑积最高,达到22.3 GPa·%,且伸长率为13.3%,远高于商用热成形钢的6.6%。XRD和磁性法测得该处理条件下的残留奥氏体含量分别为5.2%和7.98%,透射电子显微镜(TEM)观察到薄膜状残留奥氏体。分析表明,淬火-配分处理后,保留至室温的富碳残留奥氏体对于提高材料的塑性起到了主要作用。

Microstructure and mechanical properties of a new hot stamping steel with high silicon content( 0. 82 mass%) after quenchingpartitioning( Q-P) treatments with different temperatures and time were studied by OM and SEM. The resules show that the microstructure of the steel consists of lath martensite and retained austenite with some M/A islands. The steel treated by Q-P process at 260 ℃ for 300 s shows the highest product of strength and elongation,which reaches 22. 3 GPa·%,and its elongation is up to 13. 3%,which is much higher than that of commercial hot stamping steel. About 8% retained austenite is detected in the steel by magnetic method,and the morphology of thin film retained austenite is confirmed by TEM observation. The carbon-rich retained austenite of the steel plays a crucial role in the improvement of its mechanical properties.