Deformation behavior and microstructure characterization of the radially forged 2A50 aluminum alloy at high-temperature solid and semi-solid states

The deformation behavior of a radially forged 2A50 aluminum alloy was investigated by thermal compression test at high-temperature solid (300–500 °C) and semi-solid (565–585 °C) states with strain rates of 0.01–0.5s–1. A strain-compensated Arrhenius constitutive equation was established to describe the relationship between flow stress and compression parameters. The inhomogeneous deformation and microstructure evolution of the specimen were explored. Results reveal that the strain-compensated Arrhenius model can accurately predict experimental flow stress in both two temperature states. In the high-temperature solid state, the equilibrium between the softening effect (dynamic recovery and dynamic recrystallization) and work hardening leads to a steady stage of the flow curves after peak. In the semi-solid temperature, the softening mechanisms mainly include the high level of dynamic recrystallization (DRX), lubrication of liquid phases, and partial collapse of solid-phase skeleton, contributing to a declining stage of flow stress after peak. Strain and temperature profoundly influence DRX. At high-temperature solid state, coarse and elongated grains predominate in the regions with small strain, whereas DRX and numerous subgrains massively occur in the regions with large strain. The entire sample compressed in semi-solid temperature is subjected to DRX, attributed to the elevated temperature compared to the high-temperature solid state. Fine DRX grains are concentrated at the center of the large deformation zone (with large strain) due to the frequent DRX. Elevating semi-solid temperature leads to the formation of large equiaxed grains. DRX facilitates the weakening of deformed textures, demonstrated by the presence of deformed textures (<111> and <100>//X0 fiber textures, <111>//Z0 fiber texture, and {110}<111> texture) in the sample at high-temperature solid state, contrasted with the absence of pronounced preferred orientation in semi-solid compressed sample.