Dilatometric analysis of austenite decomposition considering the effect of non-isotropic volume change

One of the important assumptions underlying conventional dilatometric analysis is that volume changes isotropically during phase transformations. However, the volume change does not in fact occur isotropically and thus dilatation data contain non-isotropic contributions. In the present study, we expand the conventional analysis model to take into account the effect of non-isotropic volume change. The contribution of the non-isotropic effect to the dilatation data is quantified and is implemented in the analysis model. Dilatometric analysis is conducted on measured dilatation data of low-carbon steels to validate the suggested model. The phase fractions evaluated with the model show a good agreement with those obtained by metallographic analysis. It can be shown that considering the effect of non-isotropic volume change is critical for quantitative dilatometric analysis.