Abstract:Impact behavior of aluminum alloy 2519A was investigated at strain rates of 600−7 000 s−1 and temperatures of 20−450 ℃ by a split Hopkinson pressure bar. The results show that the flow stress is dominated by temperature, and it increases with strain rate and decreases with deformation temperature. The serrated flow curves show the dynamic recrystallization occurs. The strain rate sensitivity exponents m determined are 0.066, 0.059 4, 0.059 0 and 0.057 3 at 20, 150, 300 and 450 ℃, respectively. Cowper- Symonds constitutive equation expressing the plastic flow behavior was calculated by analysis and regression of the experimental results. The fracture characteristics under the experimental conditions were observed by optical microscopy(OM) and scanning electron microscopy(SEM). It is determined that the tested material fails as a result of adiabatic shearing.

Key words: aluminum alloy 2519A; split Hopkinson pressure bar; dynamic recrystallization; strain rate; adiabatic shearing