Dimensional Change of Selectively Laser-Melted and Gravity-Cast AlSi10Mg Alloy During Heat Treatment

Abstract

AlSi10Mg alloy, processed by selective laser melting (SLM) in as-built state and gravity casting in solution-treated state, was heat-treated at several temperatures for different durations, and the resulting dimensional changes were investigated. For the cast AlSi10Mg alloy, the linear dimensional change heat-treated at 200 ˚C was approximately 0.10%, which agreed with that calculated by a theoretical model. The linear dimensional change of the SLM AlSi10Mg alloy heat-treated at 150 ˚C was 0.17%. This indicated that, in as-built state, the concentration of supersaturated solid solution Si in α-Al phase was 1.7 wt% on average, and the lattice constant of α-Al phase was 0.4047 nm. SLM AlSi10Mg alloy contained more than 3 cm3/100 g-Al hydrogen and showed a linear dimensional change of more than 0.6% after the heat treatment at 530 ˚C because of porosity expansion. The relative densities of the SLM AlSi10Mg alloy heat-treated at 150 ˚C for 1800 ks and 530 ˚C for 18 ks were 99.89% and 98.12%, respectively.