Minimizing Residual Stresses in Gamma-TiAl Produced by Electron Beam Melting Process

Gamma titanium aluminide (Gamma-TiAl) alloy is a potential material for manufacturing turbine blades in advanced aircraft engines. One of the challenges the industry faces today is how to shape this material. This is because the conventional machining and casting routes have proved to be insufficient when dealing with the brittle nature of this alloy, typical of an intermetallic compound. Recent attempts suggest that electron beam melting (EBM) which is an additive manufacturing technique could successfully build 3D components from Gamma-TiAl. The process has an extremely intense beam that can melt this alloy despite the alloy’s very high melting point and at the same time contamination from atmosphere can be avoided as the entire build is enveloped in vacuum.

Electron beam melting of Gamma-TiAl is not entirely without challenges. For example, because of the sensitive nature of the alloy to heating and cooling cycle, residual stresses build up in EBM produced parts. In this work, experiments would be carried out on EBM to produce Gamma-TiAl, and understand how different settings influence residual stresses. Heat treatments that could further reduce the residual stresses without affecting the microstructure would also be investigated. Simulation of EBM process would be taken up to understand where and how these residual stresses in fact start to occur within a given geometry.

'This work was supported by NSTIP strategic technologies program number (11-ADV1494-02) in the Kingdom of Saudi Arabia