Abstract:Hot deformation behavior of extrusion preform of the spray-formed Al-9.0Mg-0.5Mn-0.1Ti alloy was studied using hot compression tests over deformation temperature range of 300-450 °C and strain rate range of 0.01-10 s^？1. On the basis of experiments and dynamic material model, 2D processing maps and 3D power dissipation maps were developed for identification of exact instability regions and optimization of hot processing parameters. The experimental results indicated that the efficiency factor of energy dissipate (η) lowered to the minimum value when the deformation conditions located at the strain of 0.4, temperature of 300 °C and strain rate of 1 s^-1. The softening mechanism was dynamic recovery, the grain shape was mainly flat, and the portion of high angle grain boundary (>15°) was 34%. While increasing the deformation temperature to 400 °C and decreasing the strain rate to 0.1 s^-1, a maximum value of η was obtained. It can be found that the main softening mechanism was dynamic recrystallization, the structures were completely recrystallized, and the portion of high angle grain boundary accounted for 86.5%. According to 2D processing maps and 3D power dissipation maps, the optimum processing conditions for the extrusion preform of the spray-formed Al-9.0Mg-0.5Mn-0.1Ti alloy were in the deformation temperature range of 340-450 °C and the strain rate range of 0.01-0.1 s^-1 with the power dissipation efficiency range of 38%-43%.

Key words: spray forming; Al-9.0Mg-0.5Mn-0.1Ti alloy; hot compressing deformation; processing map; dynamic recrystallization