Transformation of ferrite in duplex stainless steel

Transformation of f e r r i t e to austenite and si^ma phase in a duplex f e r r i t i c - a u s t e n i t i c stainless steel containing the equivalent of 25% Cr and 1% Ni was investigated by optical and electron microscopy. The morphologies of the product structures and kinetics of transformation were determined over the temperature range D O 1200 C to 600 C using specimens that had been isothermally treated. The nucleation and difiusional growth of austenite into a Widmanstatten plate morphology was found to occur f i r s t on the f e r r i t i c grain boundaries followed by intergranular precipitation. The kinetics of formation of austenite was determined