Influence of Fatigue Damage on the Polythionic Acid Corrosion-resistance of Bellows

In connection with the polythionic acid stress corrosion problems on the bellows used in the catalytic cracking unit,the polythionic acid stress corrosion properties of solid solution Incoloy825 bellows were investigated.Surface topography and corrosion characteristics of the bellows were analyzed by means of metallographic microscope,scanning electron microscopy(SEM),energy disperse X-ray detector(EDX).The results indicate that cumulative fatigue damage and design fatigue life have remarkable influence on the corrosion sensitization.The greater the fatigue damage accumulated and the shorter the fatigue life designed,the more easily the stress corrosion cracking forms.