Effect of heat treatment on the dynamic impact response of Cu–Cr–Zr alloy manufactured by laser powder bed fusion

Abstract

This study investigates the effect of heat treatment on the dynamic impact behavior of a Cu–Cr–Zr alloy fabricated via high-power laser powder bed fusion (LPBF). Experiments utilized a split Hopkinson pressure bar (SHPB) setup with firing pressures of 100 kPa and 250 kPa, corresponding to maximum strain rates of 4400 s^-1 and 11300 s^-1 for as-built samples, and 1700 s^-1 and 4700 s^-1 for heat-treated samples. True stress-strain curves reveal a significant difference in strain accommodation mechanisms between as-built and heat-treated samples. Heat treatment markedly enhances the ultimate compressive strength (UCS) and work hardening rate under dynamic loading conditions, likely due to the Orowan strengthening mechanism by finely dispersed precipitates formed during heat treatment. The heat-treated samples exhibit continuous strength gains with increasing strain, reflecting pronounced strain hardening. In contrast, as-built samples show a plateau after reaching their UCS, where the activation of softening mechanisms, such as adiabatic shear band (ASB) formation, reduces the effectiveness of strain hardening. Despite the substantial changes in mechanical behavior, macro-texture analysis reveals minimal differences between as-built and heat-treated samples, suggesting that the performance disparities stem primarily from microstructural changes, such as precipitate formation and distribution in heat-treated samples, rather than shifts in crystallographic orientation.