1800 MPa热冲压用钢的连续冷却相变组织和性能研究  

Study on Microstructure and Properties of Continuous Cooling Phase Transformation for 1800 MPa Hot Stamping Steel

作　　者：刘浩[1,2] 谭宁 金鑫焱[1,2] LIU Hao;TAN Ning;JIN Xinyan(Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China;State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel),Shanghai 201900,China)

机构地区：[1]宝山钢铁股份有限公司中央研究院,上海201900 [2]汽车用钢开发与应用技术国家重点实验室(宝钢),上海201900

出　　处：《热加工工艺》2025年第6期112-115,121,共5页Hot Working Technology

摘　　要：在传统1500 MPa热冲压用钢22MnB5基础上,通过成分优化开展1800 MPa热冲压用钢研发与样件组织性能评估研究。采用热膨胀仪测量1800 MPa实验钢不同冷却速率下温度-膨胀量曲线,结合扫描电镜微观组织和显微维氏硬度,获得不同冷却速率下实验钢冷却相变规律,并绘制成CCT曲线。结果表明:当冷却速率低于1℃/s时,组织中包含铁素体与珠光体;当冷却速率增加至2℃/s时,组织中出现部分贝氏体;当冷却速率高于10℃/s,组织全部转变为马氏体,同时实验钢基板硬度增加至500 HV以上,且后续不再发生显著变化。根据上述连续冷却相变规律开展保险杠样件热冲压试制与评估,实验钢热冲压零件抗拉强度达到1851 MPa,相对于22MnB5的1525 MPa提升21.3%,其伸长率和弯曲性能良好,热冲压保险杠最大变形量相对于22MnB5零件减少32%,其最大载荷提升20%。On the basis of the traditional 1500 MPa hot stamping steel 22MnB5,the research and development of 1800 MPa hot stamping steel and tissue performance evaluation research of the sample were carried out through the composition optimization.Thermal expansion instrument was used to measure the curve of temperature-expansion at different cooling rates of 1800 MPa experimental steel.Combining SEM microstructure and microhardness,the cooling phase transition law of the experimental steel under different cooling rates was obtained,and the CCT curve was plotted.The results show that when the cooling rate is less than 1℃/s,the microstructure contains ferrite and pearlite.When the cooling rate is increased to 2.0℃/s,partial bainite appears in the microstructure.When the cooling rate is greater than 10℃/s,the microstructure is all converted to martensitic,and the hardness of the experimental steel substrate increases to more than 500 HV,and no significant changes occur later.According to the above results,the hot forming trial production and evaluation of bumper bar samples were carried out.The tensile strength of the hot forming part of the experimental steel reaches 1851 MPa,which is 21.3%higher than that of 22MnB5(1525 MPa),and its elongation and bending performance are good.Compared with that of the 22MnB5 parts,the maximum deformation of the hot-formed bumper is reduced by 32%,and its maximum load is increased by 20%.

关 键 词：热冲压用钢 CCT曲线 显微组织 样件性能 

分 类 号：TG161[金属学及工艺—热处理]