Effect of heat treatment time on the microstructure and mechanical deformation behavior of additive-manufactured AlSi10Mg components

The AlSi10Mg alloy was developed using a selective laser melting (SLM) process, followed by stress relieving at \(300^\circ \hbox {C}\) for 2 and 4 h respectively. The effect of the heat treatment time on the microstructural and mechanical properties was determined. AlSi10Mg powder with an average particle size of \(47\,\upmu \hbox {m}\) was successfully melted with laser energy density of \(53.7\,\hbox {J/mm}^{3}\). The samples were examined using both a scanning electron microscope and an optical microscope, to determine their microstructural properties. The samples were subjected to a tensile test and nano-indentation in order to determine the effect of heat treatment time on the microstructures and mechanical properties. The 2-h stress relieved alloy revealed fine silicon precipitates within the semi-elliptical track. The 4-h stress relieved alloy formed coarser silicon precipitates without semi-elliptical tracks. The results showed: improvement in deformation behaviour, with an increase in stress-relieving time; while the strength was compromised. The 2-h stress relieved sample showed higher strength, due to the fine silicon precipitates, when compared to the 4-h stress relieved sample, which showed excellent ductility. The lower strength was attributed to coarser silicon particles within the microstructure.