某大型调质输入轴放置约9个月后开裂, 采用宏观分析、化学成分分析、低倍检验、断口分析、金相检验以及力学性能测试等手段对输入轴开裂原因进行了分析。结果表明: 该输入轴为在组织应力及氢析出所造成内应力共同作用下的氢致延迟开裂; 输入轴原材料氢含量高、偏析严重、非金属夹杂物含量高以及锻造不充分, 引起零件内部发生了氢气积聚, 形成了较大的内应力, 这是导致输入轴发生氢致延迟开裂的主要原因。

Cracking was found in a heave-duty thermal refined input gear axle after 9 months storage period. Analysis was performed on the cracking zone by chemical compositions analysis, macroscopical and microscopical examination, fracture analysis and mechanical properties testing to find the cracking reason of the input gear axle. The results show that the input gear axle failure resulted from hydrogen induced cracking. The main reason for the cracking was high hydrogen content, serious segregation and many nonmetallic inclusions in the raw material, and insufficient forging, which made large interior stress form and hydrogen gather in the input gear axle, and hydrogen induced cracking happen finally.