Electrochemical reactivation methods applied to PM austenitic stainless steels sintered in nitrogen–hydrogen atmosphere

Abstract

Exposure methods (ASTM A262 Practice A and Modified Strauss Test) and electrochemical reactivation methods such as EPR and EPRDL was applied to PM 304L and PM 316L stainless and comparisons with wrought stainless steels were made. Sintering in vacuum and nitrogen–hydrogen atmosphere was chosen. The latter was the focus of the work and the former was used on comparative basis. It was seen how nitrogen in PM stainless steels plays a relevant role both when is dissolved and when is in intermetallic precipitates. A set of heat treatments were applied: annealing and sensitizing at 375, 675 and 875 °C. The results indicate that the electrochemical reactivation methods are suitable to evaluate the degree of sensitization of PM austenitic stainless steels.