Mesostructure of the localization in prestrained mild steel

Abstract

In polycrystals, strain localization, i.e., sets of narrow bands carrying a large amount of plastic deformation, corresponds to an instable phenomenon, frequently observed during cold forming processes. In order to simulate such processes and their effect on localization, changes in loading path were extensively investigated at macroscopic and microscopic scales, but only little information is available on the evolution on the local strain field during localization. The aim of this paper is to analyze the evolution of local strain fields within the macroscopic bands of localization and to describe an intermediate scale, called meso-scale. This evolution was investigated at the surface of the samples, thanks to microextensometry techniques developed within a scanning electron microscope (SEM). The studied material was a mild steel, prestrained in plane tension parallel to the rolling direction, then tested in uniaxial tension parallel to the transversal direction.