Quantitative Analysis of Intermetallic Precipitates in High Mo Superaustenitic Stainless Steel

Abstract

Influence of ageing temperatures and ageing time intervals on the intermetallic phases of high Mo superaustenitic stainless steel (SASS) is studied. To form the intermetallic phases the alloy was aged for 1 hour and 10 hours at different temperatures in the range of 500-1000°C. Chi forms at temperatures up to 800°C. Sigma forms above 900 or 1000°C depending upon the ageing time. A property diagram is simulated using Thermo-calc software to corroborate the formation of chi and sigma phases as a function of ageing temperatures. EDS of sigma indicated its higher Mo content compared to the chi phase. Chi is enriched in chromium while sigma is enriched in Mo.