How defects depend on geometry and scanning strategy in additively manufactured AlSi10Mg

Abstract

• Defect volume and morphology depend on component geometry. • Overhangs and small geometrical features elicit high local porosity levels. • Geometry dependent porosity can be influenced by process settings. • Too small scan line spacing causes melt pool instability. Porosity is an inherent feature of additively manufactured components that impairs the mechanical properties. Since porosity depends not only on the process parameters but also on the component geometry, it is necessary to investigate this dependency. This study reveals relationships between porosity, process parameters and component geometry in AlSi10Mg specimens. Micro-computed tomography images of different geometries built with varying parameters were analysed for pore concentrations. The quantity and distribution of pores at overhangs depends on the laser scan speed and the width of the overhang. Similarly, the scan speed influences the effective bead width and thus the pore formation at thin structures. This relationship is revealed by an in-depth analysis of the laser path together with the μCT images. The investigations show that the process parameters can only be optimal for a specific geometry. The presented interdependencies can be used to derive locally adjusted scanning strategies and machine parameters.