DP780冷轧汽车用钢冲压开裂失效分析  

Failure analysis of stamping cracking of DP780cold rolled automobile steel

作　　者：韩世绪 赵轶哲 薛仁杰 董伊康 张馨月 程吉顺 HAN Shixu;ZHAO Yizhe;XUE Renjie;DONG Yikang;ZHANG Xinyue;CHENG Jishun(HBIS Material Technology Research Institute,Shijiazhuang 050023,China;Tangshan Iron and Steel Group Co.,Ltd.,Tangshan 063001,China)

机构地区：[1]河钢材料技术研究院,河北石家庄050023 [2]唐山钢铁集团有限责任公司,河北唐山063001

出　　处：《轧钢》2025年第1期71-77,92,共8页Steel Rolling

基　　金：河北省创新能力提升计划项目(23561006D);中信铌钢发展奖励基金项目(2023FWNB-30122)。

摘　　要：针对汽车用钢冲压开裂的问题,以1.5mm厚度DP780带钢为研究对象,采用金相显微镜、扫描电镜、拉伸试验机等设备,对其在冲压成形过程中出现开裂的原因进行了研究,并提出了改善措施。结果表明:DP780带钢在冲压过程中剪切间隙为0.3mm时,其剪切面冲压光亮带占比为30%,剪切边无缺陷,冲压质量最优;带钢组织中铁素体、马氏体体积分数比为7:3,且带钢屈强比不高于0.6时,铁素体、马氏体双相组织的协同变形能力对DP780双相钢成形性更有利;提高退火温度,可降低DP780双相钢奥氏体中的C浓度,提高铁素体组织占比,降低马氏体强度;提高过时效温度,可以促进淬火马氏体中位错的回复,降低马氏体硬度。当退火温度提高20℃,过时效温度提高40℃时,DP780带钢屈服强度均值降低了30MPa,n值提高了0.02,r值提升了0.15。经剪切间隙调整、退火工艺优化后,DP780带钢冲压零件剪切面质量显著提升,断面未发现有明显的撕裂带,零件不发生开裂,冲压成材率由82%提升到98%以上。Aiming at the problem of stamping cracking of automobile steel,taking DP780dual-phase steel strip with thickness of 1.5mm as the research object,the causes of cracking during stamping forming were studied by means of metallographic microscope,scanning electron microscope,tensile testing machine and other equipment,and the improvement measures were put forward.The results show that when the shear clearance is 0.3mm in the stamping process of DP780dual-phase steel strip,the proportion of stamping bright band is 30%,the shear edge has no defects,and the stamping quality is the best.When the volume fraction ratio of ferrite and martensite is 7:3,and the yield ratio of strip is not higher than 0.6,the synergistic deformation ability of ferrite+martensite dual phase is more favorable for forming.Increasing the annealing temperature can reduce the carbon concentration of austenite,increase the proportion of ferrite and reduce the strength of martensite.Increasing the overaging temperature can improve the recovery of dislocations in quenched martensite and reduces the hardness of martensite.When the annealing temperature is increased by 20℃and the overaging temperature is increased by 40℃,the average yield strength of DP780dual-phase steel strip is reduced by 30MPa,the nvalue is increased by 0.02,and the r value is increased by 0.15.After adjusting the shear clearance and optimizing the annealing process,the quality of the shear surface of DP780dual-phase steel stamping parts is significantly improved,no obvious tearing zone is found in the section,and no cracking of parts.The stamping yield is increased from 82%to more than 98%.

关 键 词：DP780双相钢 冲压开裂 显微组织 力学性能 剪切间隙 退火工艺 

分 类 号：TG3[金属学及工艺—金属压力加工]