Carbon Content and Grain Size Effects on the Sensitization of AISI Type 304 Stainless Steels

The sensitization domains of three AISI 304 austenitic stainless steels, differing only by their carbon content or grain size, have been determined using the ASTM A 262 Practice E and the EPR tests, in order to study the carbon content and grain size effects on sensitization kinetics in the temperature range 600 to 800 C. It has been found that increasing the grain size delays the beginning of the sensitization at the lower temperature considered in this study (600 C) and considerably delays desensitization. Decreasing the carbon content lowers the maximum temperature for sensitization (T_K), but the discrepancies found between the results of the above-mentioned tests did not allow any other conclusion. As a consequence, the performance of these two tests has been compared, but some disagreements remain unexplained.