Tensile stress-strain characteristics of an AC4CH-T6 aluminum casting alloy at high strain rates

摘要

High strain-rate tensile stress-strain characteristics of AC4CH-T6 aluminum casting alloys are evaluated using the split Hopkinson bar. Tensile stress-strain data up to fracture are determined at strain rates of 500-800/s and compared with those at quasi-static and medium strain rates obtained on an tensile testing machine. The effect of Strain rate on the tensile strength, elongation at fracture and absorbed Instron is investigated. It is shown that the tensile strength increases slightly, whereas the elongation at fracture and the absorbed energy decrease considerably with increasing strain rate. Microscopic examination reveals almost no difference between the static and impact fracture surface morphology of tension specimens. The large variation of the tensile properties is primarily attributed to the presence of microshrinkage defects within the aluminum casting alloy.