Cause of Leakage on 316L Stainless Steel Plate Heat Exchanger

The leakage accidents of 316L stainless steel plate heat exchanger occurred frequently after using for about half a year. The causes of leakage were analyzed by means of scanning electron microscope, energy spectrum analysis, metallographic examination, microhardness test and finite element simulation analysis. The results show that stress corrosion cracking occurred in 316L stainless steel plate, resulting in leakage. Large residual tensile stress and Cl^- corrosion medium existed in the environment after cold working, leading to cracks and corrosion pits at the wave crest and valley with large residual stress, which were the main reason for the early cracking of plate. High temperature working environment accelerated the generation of pitting corrosion and the initiation and propagation of cracks, and finally the plate leaked.