1500MPa级酸洗热成形钢开发

DEVELOPMENT OF 1500 MPa GRADE PICKLED HOT STAMPING STEEL

汽车轻量化已经成为汽车行业新的发展趋势,而轻量化的最重要途径之一是采用高强或超高强度钢,从而在不降低碰撞安全性时大幅降低汽车重量。高强钢在冷成形过程中易存在开裂、回弹大等问题,热成形技术可将高温成形与淬火强化相结合,有效解决强度与成形性两者间的矛盾。本文以此为思路,采用C-Mn-Cr-Nb-Ti复合微合金成分设计,结合TMCP控轧控冷工艺,成功开发了1.8~8.0 mm厚度规格1500 MPa级酸洗热成形钢。经检测,热成形前基板显微组织为铁素体、珠光体,屈服强度350~480 MPa,抗拉强度490~630 MPa,断后延伸率16%~27%;热冲压成形后显微组织近乎全部为板条马氏体,屈服强度1000~1200 MPa,抗拉强度≥1500 MPa,断后延伸率≥5%。将该热成型钢板应用于汽车零件B柱,冲压过程中钢板成形性良好,无开裂起皱等缺陷,完全满足客户的使用要求。

Automotive lightweight has become a new development trend in the automotive industry,and one of the most important ways to lightweight is to use high-strength or ultra-high-strength steel,to significantly reduce the weight of the vehicle without reducing the crash safety.High-strength steel is prone to cracking and rebound in the cold forming process,and hot forming technology can combine high-temperature forming with quenching strengthening to effectively solve the contradiction between strength and formability.Based on this idea,this paper successfully developed 1.8~8.0 mm thickness 1500 MPa grade pickled hot stamping steel by using C-Mn-Cr-Nb-Ti composite micro alloy composition design and TMCP controlled rolling and cooling process.After testing,the microstructure of the substrate before hot forming was ferrite and pearlite,the yield strength was 350~480 MPa,the tensile strength was 490~630 MPa,and the elongation after breaking was 16%~27%;After hot stamping,the microstructure is almost all slatted martensite,the yield strength is 1000~1200 MPa,the tensile strength is≥1500 MPa,and the elongation after breaking is≥5%.The hot-stamped steel plate is applied to the B-pillar of automobile parts,and the steel plate has good formability during the stamping process,without cracking and wrinkling and other defects,which fully meets the requirements of customers.