Limitations on the hardness increase in 316L stainless steel under dynamic plastic deformation

The aim of this study was to probe the limits of hardness elevation with increasing compressive strains under dynamic plastic deformation (DPD) conditions in an austenitic stainless steel of low stacking fault energy. 316 L was compressed at a strain rate of 80 s(-1) at engineering strains ranging from 20% to 80%. A combination of twin boundaries, dislocation networks and grain refinement led to a hardness increase of 150% at a compressive strain of 80%. However, the strength versus strain behavior was observed to be asymptotic and thus did not provide benefits of strength elevation with strain at strains beyond 60%. At such high strains, strong texture development towards {110} plane was observed in this study. This texture has a low Schmid factor for deformation twinning. Twin formation and twinning induced grain size refinement was experimentally observed to have saturated with higher strains verifying the critical role of Schmid factor in limiting the deformation by twinning. Dislocation activity was found to level off at strains beyond 60%. This implies that beyond an optimum value of strain, no significant strengthening can be achieved with additional straining under DPD conditions in 316L. Moreover, texture development has serious implications for the mechanical and corrosion properties of 316L.