Failure analysis of cracking in S30408 weld joint between cylinder and flange of pure steam sterilization pot

Abstract

The sterilization pot is widely used in the production and processing of food. The cracking failure of S30408 cylinder-flange weld joint of sterilization pot was analyzed by through the analysis of the composition, macroscopic fracture morphology, metallographic morphology, residual stress, microhardness and finite element modelling. The reasons for cracking and corresponding preventive methods were put forward. The cracking in inner surface of flange is induced by the stress corrosion cracking and accelerated by fatigue. The corrosion resistance deterioration of materials and the existence of dissolved oxygen and chloride ions are the main reasons to induce cracking. The cyclic tensile stress in weld joint accelerated crack propagation in inner surface. In order to avoid crack of sterilization pot, the reduction method on welding residual stresses should be performed and the contents of chloride ion and dissolved oxygen in the medium should be strictly monitored.