Experimental research on mechanical property size effects of AISI D2 steel

Quasi-static and dynamic shear deformation of hat shaped specimen with three different widths of shear zone (800, 400, 50 μm respectively) were performed by electronic universal testing machine and Split Hopkinson Pressure Bar(SHPB)at room temperature. The size effects of AISI D2 steel mechanical property were studied. The experimental results show that the flow stress and failure strain of material increase with the decrease of shear zone widths, however the shear zone widths which induce the size effect of flow stress and failure strain are different. Based on the Johnson-Cook constitutive model, the constitutive relation of material with different shear zone widths was fitted by the experiment results. The item of strain rate sensitivity is modified, and the modified Johnson-Cook constitutive model agrees well with the experimental results.