The effect of strain path reversal during hot rolling on austenitic stainless steel

During flat rolling the metal undergoes complex strain paths due to the interaction of the stock with the rolls. These changes in strain path affect the stored energy and hence the recrystallisation behaviour of the material on annealing. The current paper investigates the effect of the roll pass schedule on the recrystallisation kinetics of type 316L stainless steel. By changing the direction of rolling and the reduction on the second pass the effect of the deformation on the recrystallisation kinetics was determined following static annealing. The effect was found to be at a maximum after lower second pass deformation, with the maximum effect at 0.8 from the centre of the sample half thickness. A forward/forward pass gave an increase in the recrystallisation kinetics at this point with more homogeneous recrystallisation seen after a forward/reverse pass. The origins of these differences were investigated by the study of the sub-structure developed during deformation. The differences in the kinetics cannot be attributed to a single microstructural feature, but to a combination of all of them.