Cr Austenitic Stainless Steel Research Articles

The nucleation and growth of widmannstätten m 23c 6 precipitation in an austenitic stainless steel

A 24% Ni, 25% Cr austenitic stainless steel containing 0.03% C has been quenched from 1150°C. and aged at 650°C and 750°C. for periods up to 2500 hr. M 23C 6 carbide precipitation occurs upon dislocations and also as random dot-like particles which show matrix strain contrast. Denuded grainboundary regions suggest that vacancies play a significant role in the formation of the dot-like particles. The particles lose coherency as they grow, forming a Widmannstätten precipitate of needles lying along 〈110〉. The precipitates are in parallel orientation with the matrix, and are bounded by two conjugate sets of {111} interface planes contained in their growth direction. Their habit is accounted for by the good atomic correspondence of the relevant planes and directions in the M 23C 6 and austenite lattices.