failure analysis of combined heat and power steel-based expansion joint used in distribution generation

Some expansion joints bellows used in buried gas engine in tehran city cracked after 1～2 years service, the cracks usually located at top of the bellows, the material of the bellows was austenitic stainless steel plate. in order to research the crack causes, one typical failure bellows was chosen in this work, the specimen cut near the crack were analyzed by the macro-analysis, micro-analysis, chemical composition analysis, optical microscopy and electron microanalysis. the results showed the interaction effects of aggressive and high stress lead to stress corrosion crack of the top of bellows