Structural Modifications in Ferritic-Austenitic Steel Induced by Heat Treatment from 600-1150 degree C.

Transformations have been studied of a ferritic-austenitic stainless steel (27 Cr, 4 Ni, 1,5 Mo) during ″solubilization″ (900-1150 degree C) and heat treatments between 600 and 900 degree C. Solubilization produces a reduction of austenite content and partial carbides dissolution. Transformations between 600 and 900 degree C follow a complex sequence: carbides precipitation along austenite-ferrite boundaries, and growth of austenite areas; independent transformation of unstable ferrite in austenite laths; nucleation and growth of sigma phase from ferrite. The kinetics of various developments in transformation has been studied by TEM and X ray diffraction.