Effects of cryogenic thermal cycling treatment on microstructure, mechanical properties and residual stress of selective laser melted AlSi10Mg alloy

Cryogenic thermal cycling (CTC), a pivotal heat treatment technology for metallic materials, holds promising potential for application in additive manufacturing alloys to improve mechanical properties and reduce residual stress. In this study, the microstructural evolution of selective laser melted AlSi10Mg alloy during CTC treatments, which were conducted at temperatures of −160 °C and 160 °C sequentially, was investigated. Meanwhile, the mechanical properties and residual stress in both the as-built and CTC-treated specimens were also evaluated using microhardness, tensile, and Raman spectroscopy testing. Results indicate that CTC treatment does not have significantly impact on the morphologies of melt pools and eutectic Si networks. However, it does promote the precipitation of Si phases and the formation of atomic clusters in alloy. Realizing a 3 %–8 % enhancement in the microhardness of alloy along with increases of 4 % and 13 % in ultimate tensile strength and yield strength, respectively. Furthermore, a substantial reduction of 71 % in residual stress is obtained in comparison to the as-built condition. With an increase in the number of CTC cycles, the quantity of precipitates increases notably, and the enhancement of mechanical properties intensifies. However, no marked variation is detected in the residual stress levels.