Heterogeneous Distribution of Microstrain Evolved During Tensile Deformation of Polycrystalline Plain Low Carbon Steel

On a macroscale, the stress–strain curve of polycrystalline steel exhibits perfectly linear behavior in the elastic tension region. We observed that the strain distribution within grains is inhomogeneous in the range of the elastic deformation region. Microstrain concentrates at some local sites which are at and near the grain boundaries or in the interior of the grains. The microstrain is pseudo-periodic, and its period increases with applied stress, tending to approach the grain size. In addition to the tension-strain concentration, the compression-strain concentration is even present in the elastic region. The pseudo-periodic and inhomogeneous microstrain is attributed to the orientation heterogeneity of grains in polycrystalline steel.