The Influence of As-Built Surface Conditions on Mechanical Properties of Ti-6Al-4V Additively Manufactured by Selective Electron Beam Melting
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Achieving a high surface finish is a major challenge for most current metal additive manufacturing processes. We report the first quantitative study of the influence of as-built surface conditions on the tensile properties of Ti-6Al-4V produced by selective electron beam melting (SEBM) in order to better understand the SEBM process. Tensile ductility was doubled along with noticeable improvements in tensile strengths after surface modification of the SEBM-fabricated Ti-6Al-4V by chemical etching. The fracture surfaces of tensile specimens with different surface conditions were characterised and correlated with the tensile properties obtained. The removal of a 650-μm-thick surface layer by chemical etching was shown to be necessary to eliminate the detrimental influence of surface defects on mechanical properties. The experimental results and analyses underline the necessity to modify the surfaces of SEBM-fabricated components for structural applications, particularly for those components which contain complex internal concave and convex surfaces and channels.
Y.Y. Sun acknowledges the support of the China Scholarship Council (CSC) for a CSC scholarship. M. Qian acknowledges the support of the Australian Research Council (ARC) through the Discovery Project Grant of DP150104719. Useful discussions with Prof. H.P. Tang, Director of the State Key Laboratory of Porous Metal Materials, Northwest Institute for Nonferrous Metal Research, Xi’an, China, are acknowledged.
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