热成形配分工艺对超高强钢组织和力学性能的影响

Effects of hot formation and partitioning process on microstructure and mechanical properties of ultra-high strength steel

用热冲压模具研究了超高强度钢30CrMnSi2Nb热冲压配分工艺,测试了两步法淬火和配分处理工艺对超高强度钢的组织演变和强塑性能的影响规律。利用光学电镜(OM)、扫描电镜(SEM)进行了微观组织观察,用X射线衍射仪(XRD)研究了残余奥氏体含量的变化规律。结果表明:热成形配分工艺可明显提高钢的塑性和强塑积;配分过程中,碳配分和均匀化在几十秒内可完成;残余奥氏体含量是决定淬火马氏体钢塑性的主要控制因素。证实了热冲压淬火和配分工艺是一种可获得超高强度兼具高塑性汽车钢板的新型热成形处理工艺。

The hot stamping and partitioning process of ultra-high strength steel 30CrMnSi2Nb was investigated by a hot stamping die. The microstrueture evolution and mechanical properties of the steel during two step quenching and partitioning process were studied in detail. Optical microscopy （OM） and scanning electron microscopy （SEM） were utilized for room temperature observations of the microstructures. The volume fractions of retained austenite in specimens were determined by X-ray diffraction （XRD）. The results indicate that quenching and parti- tioning treatment is highly effective for increasing the ductility and product of strength and ductility. The carbon partitioning process can finish in tens of seconds. The volume fraction of retained austenite is a prime factor that determines the ductility of the quenched martensitic steel. It is suggested that hot stamping-quenching-partitioning treatment is an innovative technology for automotive plate in achieving excellent combination of ultra-high strength and ductility.