Processing map of as-cast 7075 aluminum alloy for hot working

AbstractThe true stress–strain curves of as-cast 7075 aluminum alloy have been obtained by isothermal compression tests at temperatures of 300–500°C and strain rates of 0.01–10s−1. The plastic flow instability map is established based on Gegel B and Murthy instability criteria because the deformed compression samples suggest that the combination of the above two instability criteria has more comprehensive crack prediction ability. And the processing map based on Dynamic Material Model (DMM) of as-cast 7075 aluminum alloy has been developed through a superposition of the established instability map and power dissipation map. In terms of microstructure of the deformed samples and whether plastic flow is stable or not, the processing map can be divided into five areas: stable area with as-cast grain, stable area with homogeneous grain resulting from dynamic recovery, instability area with as-cast grain, instability area with the second phase and instability area with mixed grains. In consideration of microstructure characteristics in the above five areas of the processing map, the stable area with homogeneous grain resulting from dynamic recovery, namely the temperatures at 425–465°C and the strain rates at 0.01–1s−1, is suggested to be suitable processing window for the as-cast 7075 aluminum alloy