Effect of heat treatment on AlSi10Mg lattice structure manufactured by selective laser melting: Microstructure evolution and compression properties

Abstract

In this paper, the effect of artificial aging (AA), solution heat treatment (SHT) and solution heat treatment + artificial aging (SHA) at different time and temperature on the microstructures and compression properties of AlSi10Mg lattice structures manufactured by selective laser melting (SLM) were systematically investigated. The microstructure of as-built sample consists of elongate cellular α-Al matrix decorated with eutectic Si network boundaries. After AA, the cellular structure is still maintained and there are a lot of nano-sized Si precipitates of the cellular structure. After SHT and SHA, the unique microstructural characteristic of as-built disappear, whereas the Si-rich cellular boundaries are transformed into Si particles and Si particles become coarse. The Si particles inhibit grain growth in the α-Al matrix, the samples have a strong 〈001〉 orientation. The digital image correlation (DIC) method was adopted to analyze the strain field and strain distribution during the compressive process. The results reveal that the SHA has the best compression properties and stable deformation mode. And the fracture mode changed from the initial brittle fracture to ductile fracture. The correlation between the microstructure evolution and the compression properties and the strengthening mechanism were discussed. Finally, the finite element analysis was carried out to simulate the static response of the lattice structure based on the optimal heat treatment parameters. The results can be used as a reference for control of the microstructure characterization and compression properties of AlSi10Mg lattice structure after heat treatment. • The correlation between the microstructure evolution and the strengthening mechanism are discussed. • With the increase of temperature and time, the Si-rich cellular boundaries are transformed into Si particles. • The precipitate of needle-like AlFeSi have a negative effect on the compression properties of AlSi10Mg lattice. • The Si particles inhibit grain growth in the α-Al matrix, the samples have a strong <001> orientation.