Sigma phase precipitation modelling in a UNS S32760 superduplex stainless steel

Sigma phase precipitation is known to have detrimental effects on mechanical and corrosion properties in stainless steels. Accordingly, heat treatments and welding must be performed carefully. For this reason, computer models which predict the evolution of secondary phases with the temperature are very useful for a good planning of industrial heat treatments or welding A semiempirical model, based on the pioneer work of Wilson and Nilsson, describing the microstructural evolution of UNS S32760 superduplex stainless steels was developed. The computer model, based on the modified Johnson-Mehl-Avrami-Kolmorgorov (JMAK) type of equation, uses information from isothermal experiments of sigma-phase transformation and predicts the transformation kinetics during a cooling process. A good agreement was found between the predicted CCT-diagram and the experimental tests.