The role of internal defects on anisotropic tensile failure of L-PBF AlSi10Mg alloys

This paper investigates the effects of defects on tensile failure of additive manufactured AlSi10Mg alloy focusing particularly on the role of large pancake shaped loss of fusion (LOF) defects lying perpendicular to the build direction (BD). Time-lapse in situ synchrotron radiation X-ray micro-computed tomography during straining reveals how, when tested parallel to the BD, the LOF defects extend laterally with straining connecting to other defects and giving rise to low plasticity and an essentially brittle failure mode. When they are aligned edge-on to the straining direction, failure is characterised by a ductile cup-cone failure with significant elongation of the defects axially and extensive necking prior to failure. The soft fish-scale melt pool boundaries were also found to affect the fracture path. These results highlight the anisotropic effect of loss of fusion defects in controlling tensile ductility and the need to minimize their size and aspect ratio. In cases where these cannot be fully eliminated the component should be fabricated such that the BD is not aligned with the dominant in-service loading direction.

Automated summary

This study investigates the effects of defects on tensile failure of additive manufactured AlSi10Mg alloy, with a focus on large pancake shaped loss of fusion (LOF) defects lying perpendicular to the build direction (BD). The results show that when tested parallel to the BD, LOF defects lead to low plasticity and brittle failure, while when aligned edge-on to the straining direction, the defects exhibit ductile failure with significant elongation and necking. The findings emphasize the importance of minimizing the size and aspect ratio of LOF defects to control tensile ductility.