Bellows had a leakage problem in the course of its work.By macroscopic and microscopic observation,energy spectrum analysis,composition analysis and metallographic structure analysis,the reasons for the failure of the bellows and the causes of the cracks were analyzed.The results show that the cracks originate from the outside surface of the bellows near the 2nd～3rd peaks from the inlet.The outer surface of the 253MA bellow works in chlorine-containing environments which causes pitting,and crack begins at the pitting point which is a stress concentration point,when exposed to external forces.The cracks extend from the outer surface to the inner surface,and eventually lead to parts leakage.
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