EFFECT OF CARBON AND NITROGEN ON GRAIN-BOUNDARY SEGREGATION IN IRRADIATED STAINLESS-STEELS

SUS304 stainless steels with carbon contents of 0.052%, 0.019% and 0.0 04% and SUS316L stainless steels with nitrogen contents of 0.095%, 0.0 32% and 0.003% were irradiated with 12 MeV Ni ions at 573 K to a dose of 1 dpa at 1 mu m depth. Microstructure and grain boundary chemical c omposition were investigated using a transmission electron microscope with a field-emission-gun (FE-TEM) at the probe size of 0.5 nm. The nu mber density of dislocation loop was higher as the carbon content was higher and was almost independent of nitrogen content. With increasing carbon and nitrogen content, the degree of Cr depletion and Si/Ni seg regation was decreased. Both carbon and nitrogen suppressed the Cr dep letion and Si/Ni segregation. The suppression effect of carbon was lar ger than that of nitrogen. (C) 1998 Elsevier Science B.V. All rights r eserved.