Abstract
Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM), is assessed from X-ray computed tomography (CT) scans. The results suggest that horizontal struts that are built upon loose powder show particularly high (~20 × 10−3 vol %) levels of pores, as do nodes at which many (in our case 24) struts meet. On the other hand, for struts more closely aligned (0° to 54°) to the build direction, the fraction of porosity appears to be much lower (~0.17 × 10−3%) arising mainly from pores contained within the original atomised powder particles.
Highlights
Additive manufacturing (AM), which proceeds by sequential micro-additions of material following a computer aided design (CAD), allows the fabrication of complex geometries, such as intricate cellular solids, as previously reported [1]
With few AM studies reported in the literature and no reports of porosity entrained within lattice structures, this paper investigates the defects generated by the Selective Electron Beam Melting (SEBM) process for 3 lattice structures of different geometries
From the results for all of the lattice in structures, it can be seen that thepoint buildthroughout conditions the lattice, with no regions the macroscopic scale of the being structure at least)atwhere porosity is more for the diamond lattice are
Summary
Additive manufacturing (AM), which proceeds by sequential micro-additions of material following a computer aided design (CAD), allows the fabrication of complex geometries, such as intricate cellular solids, as previously reported [1]. Selective Electron Beam Melting (SEBM) is one AM route that is becoming increasingly popular This method may be employed to process light-weight structures [2], bio-compatible materials [3] and heat transfer media [4], among other things. A significant fraction of these internal pores is considered to arise from gas entrapped in the atomised powder particle feedstock [6]. Such pores are mobile in the melt pool created when powders are molten, and are re-arranged onto patterns in the resulting solid that appear to correlate to the beam path [7]. This is not the Metals 2017, 7, 300; doi:10.3390/met7080300 www.mdpi.com/journal/metals
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
