Evaluation of austenite reformation in duplex stainless steel weld metal using computational thermodynamics

This paper provides a theoretical study of austenite reformation during cooling of duplex stainless weld metal using computational thermodynamics and kinetics. Model alloys of the superduplex 2509 weld metal and 2205 base material were used for the study and austenite reformation was calculated at equilibrium conditions and at cooling rates from 0.01 to 2,000 K/s. The calculations also provided the possibility to study the distribution of the alloying elements at ferrite and austenite phase boundaries. The importance of nitrogen for austenite reformation at rapid cooling was studied by comparing with simulations for a low-nitrogen alloy. The results were also compared with experimental and model results from the literature providing good correlation and the unique possibility to study the distribution of alloying elements between the growing austenite and the shrinking ferrite.