Video: SEAM Youtube Channel
Additively manufactured intricate designs often involve internal features or surfaces that are difficult to post-process for an improved surface finish. Their existence affects the performance of the manufactured part, especially under cyclic loading conditions. The topography of an as-built metal surface by powder-bed-fusion additive manufacturing (PBF-AM) is complex and determined by a myriad of factors, beginning with the slicing of the STL file to the removal of support structures from the part after AM. Using the PBF-AM of the Ti-6Al-4V alloy as an example, the first part of this article discusses the formation of different types of surfaces by PBF-AM. Representative surface features are outlined through selected examples. The second part presents a systematic investigation of the influence of the as-built surface condition on the tensile and fatigue properties of Ti-6Al-4V additively manufactured by selective electron beam melting (SEBM). Four distinctly different surface finish conditions are studied, without or with subsequent hot isostatic pressing (HIP) to eliminate the influence of internal defects. A range of useful observations are made from these detailed experimental studies. On this basis, the last part of this article discussed essential design considerations in order to achieve consistent as-built surface conditions for desired mechanical performance.
Professor Ma Qian currently holds a Distinguished Professor appointment at RMIT University. His research is centred on metallic materials and their manufacturing by various approaches, including additive manufacturing, solidification processing, powder metallurgy, dealloying and surface deposition. With his team members and collaborators, he has published 240 journal papers and 62 other peer-reviewed articles, which have attracted nearly 10,000 Scopus citations. He is a highly ranked metallurgist based on a published study of the research impact of author outputs in Scopus from 1996 to 2017.
Distinguished Professor Ma Qian (RMIT University)
29 July 2020