On the use of model alloys as a way to understand the effects of complex deformation conditions on austenite microstructure evolution during hot metal forming processes

Abstract

During industrial hot metal forming processes, deformed metal undergoes complex strain history that in most cases is non-linear. This very often leads to improper prediction of microstructure evolution and properties of final metal forming products by the computer models that are used currently as in most cases, they are not strain-path sensitive. In the present work, effect of strain path changes on the austenite microstructure evolution has been studied using a special group of model alloys that were designed for this purpose. These alloys are characterised by similar stacking fault energy and flow behaviour to low carbon steels at elevated temperatures, and most of all, by the fact, that austenite in these alloys is stable all the way down to room temperature, what in turn, allows to study its behaviour directly. In the current works, the results of the study of the effects of complex strain path changes on the kinetics of static recrystallisation, strain-induced precipitation process and development of grain boundaries of deformed austenite are shown. Presented results will be very useful as an input data for the computer simulation of metal forming processes towards their improvement in order to take into account full strain path history during deformation processes at elevated temperatures.