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Comparative Study on Hot Corrosion Behaviour of Selective Laser Melted Ti-6Al-4V Alloy
K. Antony, Rakeshnath T.R, A. Sankar, Bharath P.B. and J.R. Ebenezer

Ti-6Al-4V is an α+β phase Ti alloy which is widely used because of its microstructural features. Complex three-dimensional (3-D) parts can be created directly from computer models by selectively melting (SLM) the metal powder using additive manufacturing (AM) technology. In this present work hot corrosion experiments were performed on the selective laser melted sample and as received sample in laboratory air and NaCl environment at 600oC for 50 cycles. The parabolic rate constants were calculated for different environments from the thermogravimetric data obtained for the samples and they show that corrosion rate is minimum in laboratory air and maximum for SLM sample in NaCl environment due to the presence of gaseous chlorides. The microstructure morphologies and the oxide scales formed upon hot corrosion was characterized by optical and scanning electron microscope (SEM) while the constituents were determined with energy-dispersive X-ray (EDX) analysis to understand the corrosion mechanisms. The high corrosion rate of SLM compared to the as-received sample was studied by analysing the area percentage of porosity. Since helicopters and planes are used in sea areas this work is practically important in the aeronautical field.

Keywords: Yb fibre laser, Ti-6Al-4V Ti alloy, additive manufacturing (AM), selective laser melting (SLM), corrosion, thermogravimetric analysis, Kp values

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