Al-Si镀层硼钢板热冲压模具磨损失效分析

Wear failure analysis on hot stamping die of boron steel sheet with Al-Si coating

针对热冲压生产过程中模具易磨损失效的问题,以Al-Si镀层板冲压用CR7V-L钢磨损退役模具镶块为分析对象,利用扫描电镜、能谱仪及显微硬度计对镶块磨损表面和剖面进行微观形貌分析、化学元素测试及硬度测量,对热冲压生产工况下模具的磨损机理进行研究.研究结果表明Al-Si镀层板热冲压模具存在特殊的磨损过程：板料镀层会粘附在模具表面,并在冲压循环中发生脱落、再粘附;同时,模具表面发生氧化和疲劳,造成材料损失并随粘附物脱离,这是造成模具磨损失效的主要原因.此外,模具亚表层硬度下降,发生明显的塑性变形,会加剧模具的磨损失效.

According to the problem of die wear failure in hot stamping process, for the wear retired die inserts of steel CR7V-L used for stamping of Al-Si coated plate, the micromorphology analysis, chemical element test and hardness measurement of the wear surface and profile of insert were conducted by scanning electron microscope（SEM）,energy dispersive spectrometer （EDS） and microhardness tester, and the wear mechanisms of die in hot stamping process were studied. The results show that there is a special wear process in the hot stam-ping die of Al-Si coated plate,namely the plate coating adheres to the die surface,and then the adhesion layer falls off and new coating re-peats the adhesion during the stamping process. At the same time,the oxidation and fatigue appeared on the die surface result in the material loss with detachment of the adhesive layer,which are the main wear mechanisms of the hot stamping die. In addition,the hardness on the sub-surface of die decreases,and the large plastic deformation occurs obviously. Thus,the wear failure of the hot stamping die is exacerbated.