Prediction of Microstructure in Laser Deposition of Titanium Alloys

Laser deposition of titanium alloys is under consideration for aerospace applications, and offers significant increases in efficiency and flexibility compared to conventional manufacturing methods. However, its ultimate success will depend on the ability to predict and control the microstructure and resulting mechanical properties of the deposit. In this study, both 2-D continuum finite element modeling and 3-D cellular automaton finite element modeling of a thinwall geometry are used to investigate the effects of deposition process variables on microstructure in laser deposited Ti-6Al-4V. Numerical results for cooling rate and thermal gradient obtained from the 2-D models are used to provide insight into grain size and morphology, while the 3-D cellular automaton models are used to provide direct predictions of deposited microstructure. The numerical model predictions are subsequently compared with observed microstructures in LENSTM deposited Ti-6Al-4V.