Evaluation of plastic deformation of a high strength alloy steel in compression at high strain rate

Thermo-mechanical instabilities leading to strain localization and occurrence of adiabatic shear bands (ASBs) significantly affect the strength of most materials at high strain rates. Adiabatic shear bands are usually harder than the bulk material and provide preferred crack initiation sites at high strain rates. It has been shown both experimentally and by finite element analysis that ASBs initiate at inhomogeneties, thus alloy steel, containing fine precipitates are more susceptible to the formation of ASBs as well as significant rise in temperature than plain carbon steels. In this study, the plastic deformation behavior of a high strength alloy steel was investigated at high strain rates. The influence of strain rate and impact momentum on shear strain localization was obtained using direct impact Hopkinson Pressure bar. The microstructure of steel specimens and the occurrence of adiabatic shear bands was analyzed using optical microscopy. It was found that the width and the hardness of the adiabatic shear bands that are formed in the steel are influenced by the applied impact momentum. The width of the shear bands becomes wider and the hardness of the shear bands increases as the impact momentum increases. © AES-Advanced Engineering Solutions.