Effect of grain size in compression deformation on the microstructural evolution of an austenitic stainless steel

Highlights: ► Increasing the starting grain size retards the dynamic recrystallization process. ► Forming compatibility is achieved by grain fragmentation in coarser structures. ► The stored GND density increases for smaller starting grain sizes. ► Nucleation process of new grains is driven by the stored deformation energy. ► Cast structured state promotes dynamic recovery as softening mechanism. - Abstract: The influence of initial grain size on the dynamic recrystallization behavior has been investigated in a commercial austenitic stainless steel. Compression tests were performed at constant temperatures of 810, 980 and 1150 °C at an average strain rate ε. of 0.01 s−1 and 0.1 s−1. In order to capture the microstructural evolution after the deformation the electron back scatter diffraction technique (EBSD) was used. The results show that nucleation of new grains is strongly grain size dependent. Increasing the grain size of the material reduces the stored energy measured in terms of kernel average misorientation, well known as driving force for dynamic recrystallization. This leads to the problem of grain refinement in coarse structured materials. Applying large plastic strains or using static recrystallization in a double hit forming process seems promising for an efficient refinement strategy.