Impact of different pore types on the tensile and fatigue properties of AlSi10Mg parts produced by laser powder bed fusion

The mechanical properties of laser powder bed fusion (PBF-LB) parts such as fatigue strength or tensile strength are greatly influenced by the porosity occurring in the material. While it is common to achieve relative densities over 99.5% for the aluminum alloy AlSi10Mg, in practice, the formation of statistically occurring oxide pores cannot be avoided completely. Due to their irregular shape, these pores are detrimental for the mechanical properties. It is hypothesized that oxide pores can be avoided by increasing the energy input. This in turn leads to the formation of spherical keyhole pores. However, it is not sufficiently understood how keyhole porosity affects the mechanical properties with regard to oxide pores. Therefore, this work investigates the impact of keyhole pores, lack of fusion pores and oxide pores on the mechanical properties of PBF-LB AlSi10Mg parts. Results show the importance of single critical defects for the fatigue behavior compared to the impact of relative porosity and reveal the less detrimental nature of keyhole pores compared to oxide pores. Despite a much higher relative porosity, the tensile strength of specimens containing keyhole pores is comparable to that of highly dense parts whereas the fatigue strength has even improved.