Root-cause Analysis of Tearing in Repoussé Panels
浮雕撕裂缺陷的冶金根因分析
标签：撕裂, 根因分析, 加工硬化, 金相
背面顶鼓时撕裂很少是单一原因：对裂纹起点取样金相显示，破裂几乎都落在减薄超过 35% 的过渡带，且粗晶显著加剧开裂——0.6 mm 紫铜退火超过 700 ℃ 即有晶粒长大风险。排查三步：①超声或千分尺测厚，圈出减薄带；②复核退火记录与测温方式；③放大检查錾面与坯面划痕，磨料压入的划痕常是裂纹源。补救方案是挖除撕裂点、氩弧焊补片后重退火再錾，切忌在脆化区直接修錾。
Tearing during pushing is rarely one-cause: metallography at crack origins shows failure almost always in transition bands thinned over 35%, made worse by coarse grain—0.6 mm copper annealed above 700 °C risks grain growth. Investigate in three steps: map the thinned zone by ultrasonic or micrometer; audit anneal records and temperature control; magnify punch and blank surfaces, since embedded abrasive scratches seed cracks. Repair by cutting out the tear, argon-welding a patch, re-annealing and re-chasing—never chase into the embrittled zone.