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 ^∘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 47μm was successfully melted with laser energy density of 53.7J/mm3. 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.