Sigma phase precipitation is known to have detrimental effects on mechanical and corrosion propertiesin 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 usefulfor a good planning of industrial heat treatments or welding. A semiempirical model, based on the pioneerwork of Wilson and Nilsson, describing the microstructural evolution of UNS S32760 superduplex stainlesssteels 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 predictsthe transformation kinetics during a cooling process. A good agreement was found between the predicted CCTdiagramand the experimental tests
