Computational analysis of austenite film thickness and C-redistribution in carbide-free bainite

Abstract

In this work, a methodology for the computational analysis of some essential microstructural features of a bainitic microstructure is developed. The focus lies in the accurate prediction of the ferritic subunit size, the thickness of the residual austenite films, their corresponding C-enrichment and the accompanying stabilization of the residual austenite. Basis of the approach is the T0-temperature concept in combination with the numerical simulation of C-diffusion profiles utilizing the cell diffusion module of the thermokinetic software package MatCalc. This methodology gives the opportunity to predict the C-distribution under consideration of consecutively forming subunits, which is necessary to estimate the C-content of austenite films. The simulations also take into account the effect of C trapping at the dislocations formed inside the ferritic platelets due to plastic deformation and its influence on the chemical potentials. Good agreement is achieved between measured and predicted retained austenite layer thickness and the C-enrichment of the layers accompanying the C redistribution process.