Necking propagated deformation behavior of layer-structured steel prepared by co-warm rolled surface nanocrystallized 304 stainless steel

Surface nanocrystallized 304ss sheets prepared by surface mechanical attrition technique were co-warm rolled at 500 °C to obtain layer-structured steel with alternate nanocrystalline layer and coarse grained layer. Tensile test results revealed that a novel tensile deformation behavior characterized by sliding and necking propagation were presented compared to the base material. In the process of tensile deformation, a sliding band occurred firstly when the stress reached the highest value, and then a necking propagated slowly at a constant speed to both ends of the sample gauge. After the first necking extended to the gauge ends, the second necking occurred before the sample cracked. The mechanical properties of the layer-structured steel exhibited both high strength and good ductility. © 2007 Elsevier B.V. All rights reserved.