In-situ measurement of local strain partitioning in a commercial dual-phase steel

This paper presents the results of an in-situ Scanning Electron Microscopy study of the local strain partitioning between ferrite- and martensite-rich regions in a commercial dual-phase steel. A Scanning Electron Microscopy tensile micro-stage, coupled with strain measurement methodologies based on gold micro-grids and digital image correlation, has been used to measure inhomogeneous strain fields at the micron scale. It has been found that when martensite is distributed non-uniformly, local strain partitioning depends significantly on the local spatial phase distribution and morphology. Strain distribution maps can be developed which provide valuable information about local strain paths for both phases. The results suggest that a rather detailed description of the two-phase microstructure of such materials is needed in order to fully understand their mechanical behaviour.