Effects of build orientation and heat treatments on the tensile and fracture toughness properties of additively manufactured AlSi10Mg

The purpose of this study aimed to examine how build orientation and heat treatments affect microstructure, and consequently, the mechanical properties obtained from tensile and fracture toughness tests of additively manufactured AlSi10Mg samples. Samples were manufactured in several orientations using a laser-based powder bed fusion (L-PBF) additive manufacturing (AM) process, following which they were subjected to three separate heat treatments: (i) stress relief at 300 degrees C for 2 h (SR); (ii) homogenization at 540 degrees C for 2 h followed by artificial aging at 170 degrees C for 8 h (HA-1); (iii) homogenization at 540 degrees C for 6 h followed by artificial aging at 170 degrees C for 14 h (HA-2). Tensile tests showed that the AB samples presented the highest mechanical strength; however, low ductility was also observed. Therefore, a model for crack propagation during tensile testing was proposed for LPBF typical microstructure. Samples subjected to fracture toughness tests showed sensitivity to porosity and microstructure. The crack-tip opening displacement (CTOD) of the AB and HA-2 samples showed similar average values of approximately 10 mu m in all three orientations. The SR samples showed the best fracture toughness behavior with average values ranging from 19 mu m to 32 mu m. The HA-1 samples presented average values between 13 mu m and 22 mu m. The fracture toughness values reported in the J-integral ranged from 6.0 to 8.4 kJ.m(-2), 10.4 to 15.5 kJ.m 2, 5.5 to 7.8 kJ.m(-2), and 4.6 to 5.7 kJ.m(-2), respectively, for the AB, SR, HA-1, and HA-2 heat treatments.

Automated summary

This study examined the impact of build orientation and heat treatments on microstructure and mechanical properties of additively manufactured AlSi10Mg samples. Tensile and fracture toughness tests revealed differences in performance under different heat treatments, and a crack propagation model was proposed for a specific microstructure.