汽车结构钢QSTE420TM冲压开裂分析及控制措施

Analysis andcontrol measures of stamping cracking of automobile structural steel QSTE420TM

针对某主机厂用酸洗板QSTE420TM冲压过程中出现的开裂问题,采用扫描电镜、金相显微镜、万能试验机等检测设备对材料断口形貌、显微组织、力学性能等方面进行系统检测分析。结果表明,QSTE420TM化学成分、力学性能均满足标准要求,显微组织以多边形铁素体+珠光体为主,未见混晶、带状组织等异常组织;开裂件断口处存在较多氧化铝、硅酸盐类等非金属夹杂物,夹杂物破坏钢基体连续性,降低钢板承载能力,夹杂物是造成钢板冲压开裂的主要原因。通过从铁水预处理、转炉冶炼、LF精炼到连铸全过程控制夹杂物的形成,强化夹杂物去除工序,提高钢水洁净度,大幅提升产品质量,有效解决了用户冲压开裂问题。

In view of the cracking problem in the stamping process of the pickling plate QSTE420TM used by a OEM,Scanning electron microscope,metallographic microscope,universal testing machine and other testing equipment are used to detect and analyze the fracture morphology,microstructure and mechanical properties of the material.The result shows,The results show that the chemical composition and mechanical properties of QSTE420TM meet the standard requirements,the microstructure is mainly polygonal ferrite+pearlite,and there is no abnormal structure such as mixed crystal and banded structure;There are many non-metallic inclusions such as alumina and silicate at the fracture of the cracked part,and the inclusions destroy the continuity of the steel matrix and reduce the bearing capacity of the steel plate,and the inclusions are the main reason for the stamping and cracking of the steel plate.Through the whole process from molten iron pretreatment,converter smelting,LF refining to continuous casting,the formation of inclusions is controlled,the inclusion removal process is strengthened,the cleanliness of molten steel is improved,product quality is greatly improved,and the problem of stamping and cracking for users is effectively solved.