Localization phenomenon investigation on Smated stainless samples by speckle interferometry

Abstract

In-plane Electronic Speckle Pattern Interferometry (ESPI) has been successfull y used during tensile tests on SMA-treated (Surface Mechanical Attrition Treatment) and as received 316L stainless steel in order to measure the strain rate field. The heterogeneity in the strain rate field can be observed from a stage of deformation which doesn’t coincide with the classic Considère’s criterion (dF=0) for the diffuse neck initiation (or plastic instability). The initiation of this heterogeneity strongly depends on treatments undergone by the material. In this paper, a comparison was performed about the heterogeneity initiation of specimens SMATed during 30 minutes with 2 mm shot, 3 mm shot and a non-treated sample. The formation of the two slip band system until fracture of the tensile specimen was also studied.