Pitting corrosion resistance of a new type of stainless steel in hot tap water

The traditional materials for the heating tubes of electric water heaters are 310S and 840 stainless steels, which are prone to corrosion and damage during service. To enhance the reliability and service life of the water heaters, we added Mo and optimized other components in 310S stainless steel to develop a new type of stainless steel, named “MD stainless steel”, specifically for heating tubes of electric water heaters. The pitting corrosion resistance of 310S, 840, and MD stainless steels in hot tap water was analyzed using electrochemical tests and surface analysis techniques. The results indicate that the pitting corrosion resistance of MD stainless steel is superior to that of 310S and 840 stainless steels, which is primarily attributed to the Mo element forming MoO, MoO2, MoO3, and promoting the formation of Cr2O3, thereby enhancing the passive film quality.