Dynamic tensile behavior of multi phase high yield strength steel

Highlights: → Experimental study on the strain rate sensitivity of multi phase 800 High Yield strength steel. → Fractographs of the broken specimens by scanning electron microscope. → The suitability of Cowper-Symonds and Johnson-Cook material models for MP800HY steel. -- Abstract: Results of uni-axial tensile testing of multi phase 800 High Yield strength steel (MP800HY) at different strain rates (0.001-750 s-1) are reported here. Flat specimens having gauge length 10 mm, width 4 mm and thickness 2 mm were tested to determine the mechanical properties of MP800HY under tensile loads. The quasi-static tests (0.001 s-1) were performed on electromechanical universal testing machine, whereas, hydro-pneumatic machine and modified Hopkinson bar apparatus were used for testing at intermediate (5 s-1, 25 s-1) and high strain rates (250 s-1, 500 s-1, 750 s-1) respectively. Based on the experimental results, the material parameters of existing Cowper-Symonds and Johnson-Cook models are determined. These models fit the experimental data well in the plastic zone. The fracture surfaces of the broken specimens are studied from their fractographs taken by scanning electron microscope (SEM).