Reassessment of low-temperature Gibbs energies of BCC and FCC in steel for T₀-temperature evaluation

Abstract

In this work, we present an improved thermodynamic modeling of the mc_fe multicomponent database on the Fe-rich side at low temperatures. This is of special interest for the prediction of bainite and martensite start temperatures. The Fe–Ni, Fe–Mn, and Fe–Cr subsystems of the Fe–Al–C–Cr–Mn–Ni–Si steel system are reassessed with particular focus on the magnetic contributions to Gibbs energies. Moreover, the predicted C dependence of the T0 line in various extensions of the Fe–C system needed improvement, which is realized by the revision of the Fe–C base in terms of the solubility limit of C in ferrite (BCC). Ternary system descriptions are adapted to the changes made in the binaries.