Spall response and microstructure evolution of additively manufactured AlSi10Mg alloy with different states

Abstract

The spall response and microstructure evolution of additively manufactured AlSi10Mg alloy with different states were investigated systematically through plate impact experiments, microstructure and texture characterization and quasi-static tensile tests. The results show that the microstructure, texture and spall response are related to the impact velocity and material state. Before deformation and fracture failure occur, the as-built and annealed specimens possess the same <001> texture along the building direction; the former consists of numerous networks, columnar grains and fine equiaxed grains, and the latter is comprised of coarser grain structure and coarse particles. For both the as-built and annealed specimens, as the impact velocity increases, the Hugoniot elastic limit (HEL) stress and spall strength are slightly affected by the impact velocity; however, the peak shock stress tends to increase. Under the same impact velocity conditions, compared with the as-built specimen, the annealed specimen corresponds to a similar peak shock stress but a lower Hugoniot elastic limit stress and spall strength. Independent of the material state, as the impact velocity increases, the damage gradually increases, namely, from incipient spall to complete spall; the grain structure, including size and shape changes; and the texture remains almost unchanged. Under the same impact velocity conditions, compared with the as-built specimen, the annealed specimen has a coarser grain structure and a similar texture. Voids tend to nucleate at grain boundaries (at the bottom of the melt pool) and large particles. Compared with the as-built specimen, the annealed specimen has greater strain rate sensitivity. The effect of the material state on the tensile strength is dependent on the strain rate, and the annealing treatment may significantly decrease the tensile strength under low strain rate conditions; and weakly decrease it under high strain rate conditions. Finally, the spall strength dependence on the material state and the effect of the strain rate on the spall behavior were discussed.