Sigma phase precipitation modelling in a UNS S32760 superduplex stainless steel

摘要

Sigma phase precipitation is known to nave 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 industriai 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 modifiedfohnson-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 CCT-diagram and the experimental tests.