LOCALIZED CORROSION RISK OF STAINLESS STEELS UNDER EVAPORATIVE CONDITIONS

摘要

Localized corrosion of stainless steels can sometimes cause unexpected failures even in environments considered harmless. A basically harmless environment can change dramatically if there is a possibility of concentration due to evaporation of water. Due to evaporation, some salts may start to precipitate and thus the ionic ratios of solution in contact with stainless steel can change. Precipitation of sulfur compounds changes the ionic relationship between chlorides and sulfates and thus enhances the risk of localized corrosion. The aim of this study is to define the dependences of localized corrosion risks on the chloride content, temperature, oxidation state and sulfate content of the solution. Special attention has been paid to such concentrations and such compositions which can form due to extensive evaporation and in situations where precipitation is also possible. A quantitative approach to model the relationships between various variables is described. The effect of concentration on aggressiveness of water is illustrated with the help of an example.