Role of Inclusions in the Atmospheric Pitting of Stainless Steel

Abstract

The fate of non-metallic inclusions in stainless steels during various periods of exposure to an industrial atmosphere was determined photographically. In addition, the rate of pit propagation was also followed. The results showed that whilst many inclusions are lost from Type 430 steel the holes left by them do not necessarily propagate as pits. It was also found that pits grow to their maximum size in a relatively short time and that increasing exposure time leads to an increase in the number of pits formed. No pitting was observed on Types 304 and 316 steel during the same exposure period of 27 months.