Mechanism of huge Luders-type deformation in ultrafine grained austenitic stainless steel

A remarkable Luders-type localized deformation having a huge Luders strain of 0.4 was observed in tensile deformation of an ultra-fine grained austenitic stainless steel fabricated by two-step cold rolling and annealing processes. It was clarified that the Luders-type deformation in the material was essentially the same as necking caused by plastic instability, but the enhanced strain hardening by deformation induced martensitic transformation realized the stable propagation of the strain localized band, leading to the huge Luders strain as well as high strength and large ductility of the material. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.