Prediction of Macrosegregation in Fe–C–Cr Alloy Casting through Coupling with Thermodynamic Phase Transformation Path

Abstract

The continuum macroscopic transport approach combined with a tabulated thermodynamic phase transformation path is established to predict the macrosegregation in Fe‐1.05 wt% C‐1.65 wt% Cr hypereutectoid steel castings. A combined partial‐equilibrium (PE) and para‐equilibrium (PA) thermodynamic approximation is developed to retrieve the phase transformation path in steels. PA routine is performed on both austenite to stoichiometric cementite transition and austenite to α‐ferrite transition in eutectoid transformation. The approach is also applied to a hypoeutectoid alloy to predict austenite to α‐ferrite transition as well as δ‐ferrite to austenite transition in mushy zone. Thermodynamic properties in macroscopic transport approach are updated by group interpolation from tabulated phase transformation path. Results show that the interaction between substitutional solute Cr and interstitial C weakens the segregation of C and the amount of cementite in the center of casting, making the C distribution more consistent with that obtained by original position statistical distribution analysis in GCr15SiMn alloy castings. This implies that including the contribution of more components can make the estimate more reasonable. The results indicate the potential of macroscopic transport prediction coupled with tabulated phase transformation path through PE + PA approximation.