中文摘要：

在商用热成形钢B1500HS成分基础上,通过提高Si含量获得一种可适用于淬火-配分（Q＆P）处理的新钢种,研究了其Q＆P处理后的微观组织与力学性能。采用光学电镜（OM）、透射电子显微镜（TEM）对材料的微观组织进行观察分析,采用磁性法（PPMS）测定残留奥氏体含量。结果表明,Si含量高的钢经Q＆P处理后得到板条马氏体＋残留奥氏体组织,而低Si含量钢为全马氏体组织。不同Si含量材料的力学性能差别明显,Si含量由0.25wt%提高至0.89wt%时,屈服强度和抗拉强度提高约80-150 MPa,且Si含量高的钢对Q＆P处理的温度和时间条件比低Si含量钢更敏感。结果显示Si含量较低的钢进行不同条件的Q＆P处理后,材料的强塑积基本不变,而Si含量的提高使热成形钢适于进行Q＆P处理,260℃×300 s条件下获得强塑积高于20 GPa·%的综合力学性能,比水淬试样强塑积高约71%。

英文摘要：

A new type of Si-modified hot stamping steel （HSS） with higher Si content compared to the commercial B1500HS steel was used.The microstructure and mechanical properties after one-step quenching ＆ partitioning （Q＆P） treatment process were investigated. It wasobserved by OM and TEM that the microstrueture of high Si content specimen comprises lath martensite and residual austenite, while themierostructure of low Si content specimen is fully martensite. In addition, the study of mechanical properties of those two kinds of steelspresents that Si content has a great impact on the elongation and strength with the 0.89wt%Si steel possessing 80-150 MPa higher tensilestrength than the 0.25wt%Si one. Meanwhile, it is demonstrated that increasing Si content to more than 0.8wt% is required when applyingQ＆P treatment process to hot stamping steel. Under the condition of 260 ℃ for 300 s Q＆P treating, the product of strength and elongation ismore than 20 GPa % , which is almost 71% higher than that of water quenching specimen.