Cellular automaton simulation of ferrite-austenite transformation in low-carbon steels

14th International Conference on Modeling of Casting, Welding and Advanced Solidification Processes, MCWASP 2015

Awaji Island, Hyogo

2015.06.11

A two-dimensional (2-D) cellular automaton (CA) model is adopted to simulate ferrite (?±)-austenite (??) transformation in low-carbon steels. In the model, the preferential nucleation sites of austenite, the driving force of phase transformation coupled with thermodynamic parameters, solute partition at the ?±/?? interface, and carbon diffusion in both the ?± and ?? phases are taken into consideration. The model is able to simulate the ferrite-to- austenite transformation during isothermal heating in the ferrite-austenite two-phase region, and the austenite-to-ferrite transformation during continuous cooling. The influences of cooling rate and ?± grain size on the final carbon concentration field are investigated. The results show that after isothermal heating at 815?°C for 300 s, the carbon concentration in both the ?± and ?? phases reach the respective equilibrium values. The simulated microstructures compare well with the SEM images. After cooling to room temperature, the carbon distribution is more uniform when cooled at 1.2?°C/s than at 7?°C/s. The carbon distributions for different ?± grain sizes cooled at 1.2?°C/s are similar. The simulation results are used to understand the mechanisms of the experimental phenomena of an enameling steel.