Effects of shell scanning and build orientation on dynamic properties of laser powder bed fusion AlSi10Mg alloy

Additively manufactured (AM) products use two scanning strategies to create the central core region and the inner region near the free-surface circumference i.e. the shell. Manufacturers usually machine the shell to meet standard mechanical property testing. However, it's essential to determine how the shell affects an AM product's mechanical properties. This study focused on the dynamic tension and compression mechanical properties of an AlSi10Mg alloy made using the laser powder bed fusion technique. Machined and non-machined samples with and without shells of different build sizes and orientations underwent testing using split Hopkinson bar systems. Machined products displayed anisotropic dynamic behavior, favoring vertically built samples for maximum dynamic stress and horizontally built samples for elongation. However, samples with a shell showed apparent isotropic dynamic behavior due to pore distribution in the shell regime. The high porosity in the shell region resulted from the high intensity of heating energy input during scanning. Differences in shell shape between Z (load parallel to the direction of the building) and XY (load tangential to the direction of the building) samples and a slower, repeated laser scanning process in the shell region contributed to differences in porosity distribution between orientations. High porosity negatively impacted mechanical behavior and reduced dynamic mechanical properties.