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

Abstract

. (2016) Quantification and characterisation of porosity in selectively laser melted Al-Si10-Mg using x-ray computed tomography. Materials Characterization, 111 . pp. 193-204. ISSN 1873-4189 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/31972/1/CT_paper_accepted_manuscript.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the Creative Commons Attribution Non-commercial No Derivatives licence and may be reused according to the conditions of the licence. For more details see: http://creativecommons.org/licenses/by-nc-nd/2.5/ A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk ACCEPTED MANUSCRIPT 2 AbstractWe used X-ray computed tomography (CT), microscopy and hardness measurements to study AlSi10-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.

Dynamic compressive response of additively manufactured AlSi10Mg alloy hierarchical honeycomb structures

“…However, the coupon aligned with the 1-axis (or 2-axis) has higher tensile strength and greater ductility than that aligned with the 3-axis. Similar anisotropy has been seen in previous work and ascribed to microstructural anisotropy stemming from the asymmetric heat flux during laser irradiation and cooling and from the preference for flaws to align in this direction [23]. The microstructures of the SLM manufactured AlSi10Mg alloy using the same materials and process as used in this study have been previously reported by Aboulkhair et al [24].…”

Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting

“…These pores could also be formed by the reactions between O2 and C which are present in small amounts during SLM processing, causing CO or CO2 gas entrapment in the SLM-built parts [39]. The non-uniform pore distribution in this process could be caused by one of the following factors: (i) the variation of surface roughness [40]; and (ii) the layer-wise build manner of the AM [41]. The variation in surface roughness results in an inhomogeneous powder distribution that leads to an inconsistent melt flow and an unstable molten pool in the successive layers [42].…”

Numerical study on load-bearing capabilities of beam-like lattice structures with three different unit cells

“…It is a widely used alloy for casting and in AM [41,42]. The hypoeutectic alloy is near the eutectic composition (12.5% Si) which is responsible for the excellent casting properties.…”