Grain Growth of Ti–6Al–4V Alloy Predicted with Cellular Automaton-Finite Difference (CAFD) Model

The grain growth mode of titanium alloys remains controversial. In this study, ANSYS and cellular automaton-finite difference code μMatIC were coupled to simulate the multi-scale solidification process of commercial purity titanium and two types of titanium alloys with different solute concentrations. Investment casting of Ti–6Al–4V was carried out in counter-gravity casting method in vacuum environment. Results showed that the grain growth mode of titanium alloys depended on the solute compositions. Grain growth mode of titanium alloys transfers from planar to dendritic with the increased solute. The grain growth morphology of Ti–6Al–4V alloy presents cellular dendritic due to slight solute segregation in the solidification. The predicted grain structure was validated by comparison with the microstructural observation results. Both the prediction and experimental results revealed that equiaxed grains were obtained in investment casting of Ti–6Al–4V regardless of the thickness. The grain size increased with the wall thickness of the cast part.