Modelling the CCT-diagram of intermetallic phase precipitation in duplex stainless steels from isothermal experiments

Background/aims:σ-phase and other intermetallic phases in substantial quantities may have detrimental effects on mechanical and corrosion properties in stainless steels. Owing to experimental difficulties, the information describing the kinetics of intermetallic phase transformation is limited especially for non-isothermal processes. Methods: A computer model, which is based on an Avrami type of equation was developed. The model uses information from isothermal experiments of σ-phase transformation and predicts the transformation kinetics during a cooling process. For instance, the computer program is capable of predicting a continuous cooling transformation (CCT)-diagram. Results and conclusions: After optimisation based on direct measurements of volume fractions of σ-phase in dilatometer specimens, the model was found to predict CCT-diagrams for σ-phase transformation in duplex stainless steels with satisfactory accuracy. The program provides a powerful tool for optimising the manufacturing of such steels.