Effects of Heat Treatment on Mechanical Properties of Selective Laser Melted AlSi10Mg Alloy

Additive manufacturing has been widely used in industries. The plasticity and fatigue behaviors of AlSi10Mg alloy parts manufactured by selective laser melting (SLM) are generally poor. Thus, this paper studies the microstructure and mechanical properties of SLM-manufactured AlSi10Mg alloy under aging, annealing, solution and T6 heat treatments. The results demonstrate that these heat treatments enhance the plasticity of the material, especially for the T6 treatment, which exhibits a plasticity 3.2 times greater than that of the as-deposited alloy. However, the tensile and yield strengths of the AlSi10Mg alloy decrease. The T6 treatment exhibits the highest fatigue life, which is five times higher than that of the as-deposited alloy. The microstructure of the annealing treatment consists of reticulated eutectic Si, while the aging treatment displays reticulated Si fractures and an increased presence of spherical Si particles. In contrast, the solution and T6 treatments exhibit blocky Si structures and micropores. The microstructural alteration of the silicon state after heat treatment is attributed to the enhanced fatigue life.