High-temperature flow softening behavior of additively manufactured AlSi10Mg alloy

This work is centered on the hot-deformation behavior of selective laser melted AlSi10Mg alloy through conducting hot-compression tests at temperatures of 150, 250, 350 and 450°C under the initial strain rate of 0.001s⁻¹. Dynamic recrystallization is observed across all thermomechanical conditions, resulting in a significant portion of flow softening. The initial microstructure exhibits an average grain size of 12.8 µm, which undergoes a reduction to 8.3, 7.1, and 7.9 µm when subjected to deformation at temperatures of 250, 350, and 450°C, respectively. In addition, the proportion of fine grains with a size smaller than 10 µm rises from 31.8% to approximately 60.6, 65.4, and 61.9% in the corresponding deformed samples. The alloy demonstrates a remarkable ability to develop substructures, with continuous dynamic recrystallization identified as the primary restoration mechanism responsible for refining the grain size of the material. The rationalization of the transition from low angle to high-angle boundaries is evident in deformed microstructures, where the microstructure consists of undeveloped grains undergoing recrystallization. These grains were adorned with both high angle and low-angle boundaries concurrently. The softening behavior of the alloy is also influenced by the mechanisms of geometrical recrystallization and fragmentation of the continuous silicon eutectic network, which occur during thermomechanical processing.