硫磺再生塔内件腐蚀失效分析

Corrosion Failure Analysis of Internals in Sulfur Regeneration Tower

目的查明硫磺再生塔内件腐蚀失效的原因,提出避免该内件再次失效的对策。方法采用目测、金相显微镜和电子显微镜以及能谱分析等手段,分析内件腐蚀失效的原因。结果能谱分析表明,该内件基体镍含量偏低,腐蚀产物中硫含量较高。目测可见内件断口表面粗糙,电子显微镜形貌与金相显微分析表明,在晶界处有大量颗粒状碳化物析出。结论导致该内件失效的原因主要是热处理不当,造成了晶间碳化物的析出,从而导致了晶间腐蚀的发生。同时镍含量偏低也降低了材料的耐蚀性,含硫腐蚀性介质的冲刷作用也加重了低耐蚀性内件的晶间腐蚀。应使用化学成分符合国标304不锈钢材料生产的内件,同时要避免内件在生产与使用过程中因热处理不当造成晶间碳化物的析出。

The work aims to find out the failure mechanism of internals in sulfur regeneration tower and put forward the solution to avoid the secondary failure. Visual inspection, metallographic microscope, energy dispersive spectroscopy(EDS) and other methods were used to analyze the corrosion mechanism of internals. EDS showed that the content of nickel in internal substrate was lower, but the content of sulfur in corrosion product was higher. The fracture of the internals was rough. Electron microscopy and metallographic microstructure analysis showed that there were a large number of granular carbides precipitated at the grain boundary. The failure of the internals is induced by improper heat treatment which causes intergranular corrosion due to the precipitation of intergranular carbide. Meanwhile, the low content of nickel element also reduces the corrosion resistance of the material. Besides, the intergranular corrosion is accelerated by the corrosive medium containing sulfur. The 304 stainless steel internals with chemical composition meeting national standard should be used to avoid the precipitation of intergranular carbide due to improper heat treatment during production and use.