Acoustic-emission investigations on the austenite decomposition in a medium-carbon steel

Continuous cooling of the austenitic phase is important in controlling the microstructure and properties of steel. At high cooling rates, the initial formation of allotriomorphic ferrite undergoes a transition to bainite and martensite. Modelling and understanding the transformation process does therefore not only involve the ferrite formation, but also the bainite and martensite formation, and especially the mechanisms of phase formation and the conditions at which the transition occurs. In the present study the acoustic-emission technique is used to obtain more information on the varying transformationprocesses in different temperature regimes. The experimental results are combined with dilatometry and metallographic data in order to gain a full view of the transformation processes and kinetics.