Quantification and characterisation of porosity in selectively laser melted Al–Si10–Mg using x-ray computed tomography

Maskery, Ian; Aboulkhair, N.T.; Corfield, M.R.; Tuck, Christopher; Clare, A.T.; Leach, Richard K.; Wildman, Ricky D.; Ashcroft, Ian; Hague, Richard J.M.

Abstract

We used X-ray computed tomography (CT), microscopy and hardness measurements to study Al–Si10–Mg produced by selective laser melting (SLM). Specimens were subject to a series of heat treatments including annealing and precipitation hardening. The specimen interiors were imaged with X-ray CT, allowing the non-destructive quantification and characterisation of pores, including their spatial distribution. The specimens had porosities less than 0.1%, but included some pores with effective cross-sectional diameters up to 260 μm. The largest pores were highly anisotropic, being flat and lying in the plane normal to the build direction. Annealing cycles caused significant coarsening of the microstructure and a reduction of the hardness from (114 ± 3) HV, in the as-built state, to (45 ± 1) HV, while precipitation hardening increased this to a final hardness of (59 ± 1) HV. The pore size and shape distributions were unaffected by the heat treatments. We demonstrate the applicability of CT measurements and quantitative defect analysis for the purposes of SLM process monitoring and refinement.

Citation

Maskery, I., Aboulkhair, N., Corfield, M., Tuck, C., Clare, A., Leach, R. K., Wildman, R. D., Ashcroft, I., & Hague, R. J. (2016). Quantification and characterisation of porosity in selectively laser melted Al–Si10–Mg using x-ray computed tomography. Materials Characterization, 111, https://doi.org/10.1016/j.matchar.2015.12.001

• Journal Article Type: Article
• Publication Date: Jan 1, 2016
• Deposit Date: Feb 25, 2016
• Publicly Available Date: Feb 25, 2016
• Journal: Materials Characterization
• Print ISSN: 1044-5803
• Electronic ISSN: 1873-4189
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 111
• DOI: https://doi.org/10.1016/j.matchar.2015.12.001
• Keywords: Selective laser melting; Aluminium alloy; Additive manufacture; X-ray computed tomography; Non-destructive testing
• Public URL: https://nottingham-repository.worktribe.com/output/979017
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S1044580315300711