Precipitation of TiN during solidification of AISI 439 stainless steel

Precipitation behavior of TiN in AISI 439 ferritic stainless steel was investigated using both thermodynamics and experiments. Calculated results using equilibrium approaches show that TiN can precipitate only when the solid-phase fraction reaches 0.2. However, TiN was observed at the surface of the water-cooled samples in our experiments, which indicates that TiN can precipitate at the initial stage of solidification when the cooling rate is sufficiently high. Therefore, in order to predict efficiently the precipitation behavior of TiN during rapid solidification, non-equilibrium effect has to be taken into account during the calculations. In this work, a model, which relates the interface temperature with the composition and growth rate at the solid/liquid interface under non-equilibrium conditions, has been developed. It is shown that the calculated results using this model are in agreement with the experimental results. •A model of non-equilibrium solidification was developed using thermodynamics.•The calculated results by the model are in agreement with the experimental results.•A solute redistribution model with incomplete diffusion in liquid was established.