Assessment of the methodologies used to determine softening and recrystallization kinetics by means of torsiontests

Different recrystallization models are now available in the literature for plain carbon and microalloyed steels. However, the attempts made to unify these models have been unsuccessful due to the considerable scatter in experimental results that support the corresponding equations. In fact, kinetics results can be separated into different groups depending on the testing procedure. In order to cope with this problem and improve the reliability of the different models, the different methods that are currently applied at laboratory need to be re-analyzed. The present work concentrates on the determination of recrystallization/softening kinetics of austenite from torsion tests. To this purpose the softening results obtained by the application of double hit torsion tests to two Nb microalloyed steels and the fraction recrystallized as determined by metallography have been subjected to a direct and an inverse analysis that takes into account the specificity of the torsiontest.