Additive repair process for Ti-structures


Titanium and its alloys are interesting for industries because of their high strength-to-weight ratio, their specific strength values at high temperature and elevated corrosion resistance. Hence, to decrease the fuel consumption, titanium alloys are the candidates to replace many components in aircraft engines production. Because of their high strength, which compromises the formability, laser additive manufacturing is one of the most attractive technique to produce titanium-based components. The aim of the present work is to investigate the achievability of laser metal deposition(LMD) as a repair process using Ti6Al2Sn4Zr2Mo (Ti6242) and γ-TiAl (TNM™) powder. The generation of single layer and multilayer deposition is examined. Ti6Al4V (Ti64) is used as a substrate for single and multilayer deposition. For the repair process, Ti6242 is used as a substrate. The influence of LMD parameters on the structures is examined. The achievability of crack-free TNM™ samples without using any preheating device is investigated. A powder distribution of 15 - 45 μm and 25 - 90 μm is used for Ti6242 and TNM™ powder, respectively. The experimentation is conducted in a Glovebox, which is not flooded, using a Nd:YAG laser source with a maximum power of 2.2 kW. Results highlights the achievability of crack-free 40 mm long single layer structures of Ti6242 and TNM™, with low porosity. 8-layers structures are achieved using Ti6242 powder. 4-layers structures are performed with TNM™ powder. Performing multilayer samples with more than 4 layers using TNM™, presents an inhomogeneous distribution of material. Parameter sets to refill a notch for both powder are successfully determinate.
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