Interface segregation study by Auger electron spectroscopy of cold-worked AISI-304 and -304L stainless steels

Abstract

It is well known that, as a result of neutron irradiation, stainless steels experience changes in the microchemistry at grain boundaries, such as nickel and phosphorus enrichment and chromium and iron depletion. In this study, Auger electron spectroscopy (AES) has been performed on grain boundaries of two austenitic stainless steels of type AISI-304 and AISI-304L in order to study grain boundary microchemistry after simulating neutron irradiation effects by cold work followed by heat treatments. Auger results from AISI-304 showed that phosphorus was present at grain boundaries in the material with and without cold work followed by heat treatments at 500°C, In the cold-worked condition, nickel enrichment and iron depletion were observed. On the other hand, Auger results from AISI-304L showed that phosphorus was present at interfaces in all material conditions and sometimes phosphorus was accompanied by molybdenum and by chromium enrichment. Cold work increased the segregation of phosphorus at grain boundaries and induced chromium diffusion away from grain boundaries in this material.