Dynamic Tensile and Compressive Behaviors of Mild Steel at Wide Range of Strain Rates

The purpose of the present paper is to investigate the mechanical behavior of mild steel at quasi-static (0.001s-1) and different rates of dynamic tensile (5-750s-1) and compressive (125-2,350s-1) strain rates. Quasi-static experiments are conducted on a universal testing machine to study the stress-strain behavior of mild steel. A hydropneumatic machine and a modified Hopkinson bar are used to investigate the dynamic tensile behavior of mild steel specimens at medium and high strain rates, respectively, whereas the specimens are tested on a split Hopkinson pressure bar to acquire understanding of the strain rate sensitivity of mild steel under dynamic compression. The effects of a pulse shaper and gauge length of the specimen in the dynamic compression tests are investigated. High-speed photography has been used to monitor the deformation of the specimen at high strain rate experiments. The applicability of the existing Cowper-Symonds and Johnson-Cook material models to represent the mechanical behavior of mild steel in a plastic zone is examined. Finally, the fractographs of the tested tensile specimens are studied using a scanning electron microscope.