Precipitation in a High Nitrogen Superaustenitic Stainless Steel

Abstract

Precipitation in a superaustenitic stainless steel of composition 24Cr-22Ni-7.3Mo-3Mn-0.5N (wt%) has been investigated. Heat treatment at 1050°C for 5 min caused a precipitate structure fairly well resembling that observed in the heat-affected zone after welding. Four different types of precipitates were identified: σ and X with size 200 to 500 nm, accompanied by Laves and R with size 50 to 200 nm. Precipitates of σ and X with faceted shapes appeared in some grain boundaries, while Laves and R with more rounded shapes coexisted in other grain boundaries and with more uniform distribution.