Heat treatment influences densification and porosity of AlSi10Mg alloy thin-walled parts manufactured by selective laser melting technique

The fully dense thin-walled structures are very important for manufacturers and customers. Selective laser melting (SLM) is mainly employed for the fabrication of thin-walled and lightweight structures of aluminum alloys, titanium alloys, etc. The goal of the paper is to study the effect of heat treatments, i.e., solution heat treatment (SHT) and artificial aging (AA) on the densification and porosity of the thin-walled specimens. Thin-walled specimens with various wall thicknesses (i.e., from 0.50 to 5.0 mm) were fabricated using AlSi10Mg alloy powder with optimal process parameters on the SLM system. The relative densities of the heat-treated specimens were compared with the as-built test specimens. The porosity development during the process and their relationship with the relative density are also studied critically by applying Archimedes’ method and optical microscopic analysis. Results showed that the densification and porosity distribution behavior is changing with the variations in the wall thickness of specimens. The lowest relative density of 93.42% was obtained for 1.50-mm-wall-thickness specimen in SHT condition. The maximum relative density of 98.61% was achieved for 5.0-mm-wall-thickness specimen in the AA condition. Finally, it is concluded that the AA has a significant influence on the low-wall-thickness (i.e., from 0.50 to 2.0 mm) specimens, and the densification is improved, and porosities are reduced due to fine grain structure and strong bonding between particles.