The effect of transformation path on the final microstructure of high- and low-silicon 0.1 wt.% C steels

Two low-carbon steels with low (0.16 wt.%) and high (1.4 wt.%) Si contents were studied using laboratory simulations of thermomechanically controlled processing. Continuous cooling and discontinuous cooling schedules were utilised to evaluate the transformation behaviour of these steels. It has been found that both the transformation history and the state of austenite prior to transformation have a significant effect on the final microstructure. Both the prior austenite condition and the amount of ferrite prior to a change in cooling rate influence the morphology of second phase. The results have shown that to predict the final microstructure and mechanical properties it is not sufficient to model the process based only on average austenite composition and solute partitioning during austenite decomposition.