On the interactions between strain path reversal and dynamic recrystallisation in 316L stainless steel studied by hot torsion

A 316L austenitic stainless steel was subjected to hot cyclic torsion tests to the same total accumulative von Mises equivalent strain of 2.0 with different amounts of reversals in order to study the effect of strain path on dynamic recrystallisation (DRX) behaviour. Both the macroscopic flow stress and corresponding microstructural analyses revealed that there is a strong influence of applied strain path on the DRX kinetics. In the case of higher deformation per pass and less strain path reversals, the combination of three effects, i.e. higher stored energy, enhanced grain boundary serration and bulging through increased grain boundary area and more developed strain-induced high angle boundaries together facilitated DRX. On the contrary, deformation of more strain path reversals combined with lower strain per pass lead to a complete suppression of DRX even at the high accumulative strain of 2.0. Proper understanding of the strain path effects on hot deformation behaviour of steels is a key factor in control and optimisation of the microstructure and properties of semi-final and final products. (C) 2013 Elsevier B.V. All rights reserved.