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

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 tem-peratures. 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.