Yuya Sakurai 1 and Koji Kakehi 1
1 Department of Mechanical Engineering, Graduate School of Science and Engineering, Tokyo Metropolitan University
Additive manufacturing(AM)is the relatively recent process suitable for small - volume production in great varieties. The microstructure of Ti-6Al-4V melted by selective laser melting(SLM)using laser as a heat source and the relationship between the microstructure and mechanical properties were investigated comparing with electron beam melting(EBM)and conventional mill-annealed specimens. The effects of built direction and heat treatment on the tensile and creep properties of Ti-6Al-4V, fabricated by SLM, were also examined. The compositional image in BSE mode and electron backscatter diffraction(EBSD)analysis revealed SLM and EBM specimens were found to consist of acicular α grain transformed from α′ martensite and very fine β distributed in α/α grain boundary. Prior β boundaries were also observed. α+β equiaxed grains were observed in the conventional mill-annealed specimen. Conventional standard heat treatment(954°C/2 h(WQ)+538°C/4 h(AC))improved tensile and creep strengths in the mill-annealed specimen, however it did not improve the strengths in the SLM specimens so much. The tensile and creep strengths were comparable between the horizontal-direction and the vertical-direction specimens, i.e., SLM specimen showed isotropic mechanical properties.
titanium-6 aluminum-4 vanadium, selective laser melting, electron beam melting, microstructure, tensile properties
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