Numeric simulation of the α/γ-phase ratio of ferritic-austenitic duplex steels

In the past, the necessity to predict the alpha/gamma-phase ratio in duplex steels gave rise to a number of empirical equations and diagrams, which, however, do not guarantee a reliable prediction. Due to the insufficient agreement between experiment and empirical calculation, the new and further development of duplex steels is still carried out by means of very time-consuming and costly experiments. The CALPHAD method (CALculation of PHAse Diagrams) [1], whose calculational realization is effected by the software program Thermo-Calc [2] in connection with the optimized thermodynamic database TCFE2 (Thermo-Calc FErrum Database, Version 2), can now be used to establish a reliable (parameter optimization), thermodynamic database for duplex steels and to estimate the phase ratio.