利用光学显微镜、扫描电镜、硬度仪、冲击试验机等对铝合金成形用H13钢压铸模具的早期失效原因进行了分析。结果表明: 该模具的失效形式为整体脆断, 其主要原因是模具钢中存在较为严重的带状偏析、非金属夹杂物、液析碳化物等组织缺陷, 同时热处理工艺也不合理; 非金属夹杂物和液析碳化物周围在热应力及机械力作用下形成了裂纹, 而带状偏析和不合理的热处理工艺降低了模具的冲击韧性, 使得裂纹迅速扩展, 最终导致了模具的早期失效。

The failure of a die casting die made of H13 steel for aluminum alloy forming was analyzed by optical microscopy, scanning electronic microscopy (SEM), hardness testing and impact testing. The results show that the failure mode of the die was brittle fracture, due to the microstructural defects including banding segregation, nonmetallic inclusion and carbide liquation in the die steel and inappropriate tempering treatment. The cracks formed around the nonmetallic inclusion and aliquation carbide due to the thermal stress and mechanical force and the rapid propagation of cracks resulting from the reduced impact toughness due to the banding segregation and inappropriate tempering treatment then led to the die′s early failure.