Prediction on phase evolution during cooling of plain C-Mn steel in solid state: a numerical study

This study presents the solid-phase transformation of a plain C-Mn steel by modelling heat transfer during its cooling. The governing equation is discretised and solved numerically. The CCT of the material is modelled to identify phases in transformation. The sum of time steps presents the total cooling time. In a time-step, isothermal transformation is considered using the Avrami equation, and the overall transformation is subsequently predicted. A real-time phase evolution is evaluated, along with temperature distribution and cooling rate in this study. The present prediction is validated with existing literature under different cooling rates. At a cooling rate of 3.33°C/s, austenite transforms into 79% ferrite in 100s, 4.8% bainite in 15s, and 16% pearlite in 33s. A good agreement is found with the existing experiments. The parametric study indicates that as the cooling rate increases, the ferrite fraction decreases, the bainite fraction increases, and the pearlite fraction remains constant.