Role of Microstructure in the High Strain Rate Shear Response of 316L SS

Shear localization is characterized by the concentration of plastic deformation within narrow bands of material and constitutes the precursor to failure in materials subjected to high strain rates. These bands have been observed experimentally but classical continuum material models have not been able to capture their development. The ability to predict this material response mechanism and accurately represent the associated deformation modes in numerical simulations is a significant undertaking from both the application and numerical method development perspectives. The aim of this research is to investigate the role of microstructure in the dynamic shear response of 316L SS, looking at natural sources of perturbation in material response such as grain structure and dislocation densities. For that purpose, CFSS-DIC samples of wrought and additively manufactured 316L SS were tested on a Split Hopkinson Pressure Bar in conjunction with in-situ high-speed infrared thermometry measurements at different strains and strain rates. The shear response of 316L SS will be discussed taking into consideration differences in starting microstructure between the wrought and additively manufactured 316L SS. Microstructure characterization and temperature measurements provided important input for the calibration of a thermodynamically-consistent dynamic recrystallization model and shed light on the energy distribution in the material during deformation, which is key for successfully modeling shear deformation.