某2A12铝合金壳体在系统分离试验时发生耳片断裂失效, 为分析其断裂原因对壳体耳片进行了化学成分分析、金相检验, 断口分析以及能谱分析。结果表明: 该壳体耳片断口为典型的木纹状断口, 断裂起源于零件表面的未溶杂质化合物聚集处; 导致其断裂的主要原因是壳体原材料挤压变形量不够, 加之淬火加热温度不足, 使材料显微组织中存在较多铸态枝晶网状不良组织和未溶化合物, 降低了材料的强度和塑性。

2A12 aluminum alloy shell lugs fracture failure occurred during system separation test, and chemical compositions analysis, metallographic examination, fracture analysis and spectrum analysis were done to the fractured shell lugs to find the fracture reason. The results show that the fracture of the shell lugs was typical woody fracture and the fracture originated from the surface gathered undissolved compounds. The main reason for the fracture was that the extrusion deformation and the quenching heating temperature were not enough, which result in a great deal of as-cast network structure and undissolved compounds in microstructure and reducing strength and ductility of the shell lugs.