Evaluation of microstructural development in electron beam melted Ti-6Al-4V

In the current work an investigation of the microstructures of EBM built Ti-6Al-4V test bars has been performed using OM, SEM, TEM and XRD. It has been found that the prior β phase, that formed during the initial solidification, possesses a column shaped morphology with growing direction parallel to built direction. Typical (α + β) structures namely Widmanstätten α platelets with rod-like β phase formed on the interfaces of the fine α grains, have been observed in the columnar prior β grains. Grain boundary α phase was found to be formed around the boundaries of the columnar prior β grains. Different phases present in the parts, especially the BCC β phases have been characterized. The TEM/EDX results indicate very high V composition in the β phase. Results of TEM/SAED and XRD also revealed that a superlattice structure could be present in the β phase. Phase transformation sequence is discussed according to the processing history and the microstructures observed.