某高温高压J型染色机机头开裂原因

Causes of head cracking of high-temperature and high-pressure J-type dyeing machine

某高温高压J型染色机机头发生开裂,通过宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析等方法,分析了机头开裂的原因。结果表明:J型染色机内染液的氯离子含量较高,氯离子在机头R部位聚集,使其内表面钝化膜遭到破坏而发生点蚀,在机头内部的工作应力和机头冷加工时产生的残余应力的共同作用下,点蚀扩展成为微裂纹,最终导致机头发生应力腐蚀开裂。

The head of a high-temperature and high-pressure J-type dyeing machine was cracked. Causes of head cracking were analyzed through methods such as macro observation, chemical composition analysis, metallographic inspection, scanning electron microscopy and energy spectrum analysis. The results showed that the content of chloride ions in dyeing solution in J-type dyeing machine was relatively high. The chloride ions accumulated in the R part of head, which damaged the passivation film on the inner surface and caused pitting corrosion. Under the combined action of working stress inside head and residual stress generated during cold working of head, the pitting corrosion spread into macro cracks, which eventually led to stress corrosion cracking of head.