Additive manufactured porous titanium structures: Through-process quantification of pore and strut networks

Titanium and its alloys are successfully used in aerospace through to marine applications. Selective laser melting (SLM) is an additive manufacturing technique, which promises to allow production of novel Ti structures. However, there is still a paucity of accepted methods for quantifying build quality. The viability of using X-ray microtomography (μCT) to quantify and track changes in morphology of SLM Ti porous structures at each stage of the post-laser melting production was tested, quantifying its quality through process. Quantification was achieved using an accessible volume tool to determine pore and strut sizes. Removal of partially sintered struts by cleaning was visualised and quantified. Eighty-eight percent of the struts broken by the cleaning process were found to have connecting neck diameters of less than 180 μm with a mean of 109 μm allowing build criteria to be set. Tracking particles removed during cleaning revealed other methods to improve build design, e.g. avoiding low angle struts that did not sinter well. Partially melted powder particles from strut surfaces were quantified by comparing surface roughness values at each cleaning step. The study demonstrates that μCT provides not only 3D quantification of structure quality, but also a feedback mechanism, such that improvements to the initial design can be made to create more stable and reliable titanium structures for a wide variety of applications. © 2014 The Authors.