Manganese Influence on Equilibrium Partition Coefficient and Phase Transformation in Peritectic Steel

The equilibrium partition coefficient (k) affected by chemical component, phase constitution and temperature is a critical parameter related to solutes distribution during steel solidification. In this study, the effect of Mn on equilibrium partition coefficient and phase transformation was quantitatively analysed. A technique according to the relative amount of δ-Fe and γ-Fe to determine the equilibrium partition coefficients of solutes in L, δ-Fe, and γ-Fe three-phases coexistence zone was proposed. Results showed that Mn promotes the generation of γ-Fe and its effect on peritectic reaction zone is significant. The equilibrium partition coefficients were determined based on the phase change and relative amount of δ-Fe and γ-Fe according to the solidification paths which undergo difference phase coexistence zone. All of \( k_{C}^{\delta } \), \( k_{Si}^{\delta } \), \( k_{Si}^{\delta + \gamma } \), \( k_{P}^{\delta } \), \( k_{P}^{\delta + \gamma } \), \( k_{S}^{\delta } \), and \( k_{S}^{\delta + \gamma } \) decrease with Mn increasing, while \( k_{C}^{\delta + \gamma } \) increases due to solute Mn promote the generation of γ-Fe forming from peritectic reaction.