A plate heat exchanger is a high-efficiency heat exchanger that is assembled from a series of metal plate（AISI316L,SMO254,Titanium,Nickel) with a certain corrugated shape. A thin rectangular channel is formed between the various sheets, and heat is exchanged through the sheets. Plate heat exchangers are ideal for heat exchange between liquid-liquid and liquid-vapor. The plate heat exchanger of the stainless steel plate will cause the heat exchanger to fail due to stress corrosion. Most of the occurrences are at the bottom of the space where the slab is formed and in the area where the scale is easy to form. The main reason for the occurrence is that the plate will inevitably generate residual stress during the stamping process. It is very difficult to completely eliminate such stress, plus the formation of multiple gaps after the assembly of the plate, the existence of the gap is easy to cause the concentration and enrichment of Cl-, together with the residual stress to form the conditions of stress corrosion, after a period of operation will produce stress corrosion, The plate is subjected to stress corrosion, the plate is perforated, and the plate is cracked in severe cases.