冲裁工艺对超高强钢边部拉伸性能影响的试验研究  

Experimental Investigation on the Effect of Blanking Process on Tensile Properties of UHSS Edge

作　　者：李亚 刘渊媛 连昌伟 LI Ya;LIU Yuanyuan;LIAN Changwei(Central Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China;State Key Laboratory of Automotive Steel Development and Application Technology(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试验室(宝钢),上海201900

出　　处：《精密成形工程》2024年第11期100-107,共8页Journal of Netshape Forming Engineering

基　　金：国家重点研发计划(2017YFB0304403)。

摘　　要：目的冲裁加工后的超高强钢板材在成形过程中会因边部开裂而显著影响生产的稳定性,针对这一问题,对超高强钢板材冲裁边部开裂行为的影响因素进行研究。方法选用DP980与QP980材料,采用模具冲裁拉伸试样,用DIC的剪切边拉伸试验研究了不同的冲裁间隙以及打磨试样边部、模具磨损情况对超高强度钢力学性能和边部拉伸能力的影响,并采用DIC方法追踪拉伸试验的断裂过程,分析边部裂纹的扩展过程和断口形貌。结果通过对比试验结果发现,冲裁试样很容易发生边部开裂,冲裁间隙越大,断裂时刻越提前,断裂伸长率越小,边部成形性能越低,在冲裁间隙为材料厚度的9%~10%时,2个钢种断裂应变均最大,边部拉伸性能相对优异,材料的边部断裂也容易受到轧制方向的影响,边部断裂最先沿着轧制方向出现在边界处。模具磨损使冲裁的试样在拉伸试验过程中更容易断裂,打磨冲裁试样边部可以提高拉伸性能。在断裂形式上,2个钢种的冲裁试样均容易从边部开裂,QP980形成横-斜裂纹,冲裁间隙增大使横向裂纹变长,而DP980试样断口则均为斜裂纹。结论相同强度等级QP980钢和DP980钢均对冲裁边敏感,冲裁边对边部拉伸性能的影响较大,可以通过选择良好的模具工况、合适的冲裁工艺参数以及增加打磨工艺等,提高材料的力学性能和边部拉伸性能。The stability of the blanking UHSS sheet is significantly affected by edge cracking during the forming process,so the work aims to study the edge cracking behavior of UHSS sheet.Shear edge tensile tests were performed by DIC method to investigate the effects of different blanking clearance,polished edges,and mold wear on the mechanical properties and the ten-sile capacity of blanking edge of DP980 and QP980 steel.The propagation process of edge cracks and fracture morphology was revealed by tracking of the fracture process on DIC.Through comparison of test results,the blanking specimen was prone to edge cracking.The larger the blanking clearance,the earlier the fracture time,and the smaller the fracture elongation and the lower the edge formability.When the blanking clearance was 9%-10%of the material thickness,both steel had the max fracture strain and the edge tensile properties were relatively excellent and stable.The edge fracture of materials was also easily affected by the rolling direction,and the edge fracture firstly appeared along the rolling direction at the blanking edge.Mold wear made the blanking specimen more easy to fracture during tensile test.Polishing the blanking edge could improve the edge quality and significantly enhance tensile properties.In terms of fracture mode,the blanking specimen was easy to crack from the edge,and QP980 formed a transverse-oblique crack form and the increasing blanking clearance made the transverse crack longer.The fracture surface of DP980 exhibited all oblique cracks.QP980 and DP980 steel with the same strength grade are both sensitive to blanking edge,and the blanking edges is easy to affect the mechanical properties of the steel.Selecting good working condi-tions and appropriate blanking process parameters and adding polishing process can improve the mechanical properties and ten-sile properties of the edge.

关 键 词：DP钢 QP钢 DIC 冲裁 模具间隙 剪切边拉伸试验 边部开裂 断裂应变 

分 类 号：TG386.2[金属学及工艺—金属压力加工]