电解水制氢不锈钢碱液过滤器开裂失效分析

Failure Analysis of Stainless Steel Filter of During Electrolysis Producing Hydrogen

摘要: 针对某电厂压滤式电解水制氢不锈钢碱液过滤器焊缝区出现腐蚀破裂情况，对截取开裂试样进行宏观、微观检查、金相检验、化学成分分析、X-射线衍射分析等检测，对焊缝区开裂进行失效分析。结果表明，电解水制氢装置碱液过滤器系碱化物溶液中引起碱脆。碱液过滤器裂纹萌生于近焊缝区的焊接热影响区部位和焊缝母材交界面的熔合线区域，以该点为起点，沿晶扩展、向金属表面深处扩展。在碱化物介质中，奥氏体不锈钢表面形成Fe₃O₄等保护膜受残余焊接应力作用而遭受破坏，再钝化过程交替进行时，发生了阳极溶解型应力腐蚀开裂。

Abstract: In order to analyze the corrosion rupture in the weld zone of stainless steel alkali solution filter during electrolysis producing hydrogen in a power plant, the cracked parts of the filter were ana-lyzed by macroscopic and microscopic examination, chemical composition analysis, X-ray diffraction analysis and other tests. The results show that: during electrolytic water producing hydrogen, the cracking in the alkali solution filter system was caused by alkali embrittlement in alkaline solution. Alkali solution filter cracks appeared between the welding heat-affected zone and the fuse line area. The crack generated in this area and propagated along grain boundaries, and then extended to the depth of the steel. In the alkali medium, the formed protective film such as Fe₃O₄, etc. on the surface of austenitic stainless steel would be destroyed by residual welding stress. The passivation and the anodic dissolution process occurred alternately, which resulted in the stress corrosion cracking.