Identification of prior β grains of additive manufactured Ti-6Al-4V alloy using electron backscatter diffraction

Prior columnar β grains are an important microstructural feature of laser powder bed fusion (LPBF) Ti-based alloys and affect the properties. The objective of this study was to reconstruct the prior β grains of heat-treated LPBF Ti-6Al-4V alloy using crystallography data of α grains from electron backscatter diffraction. The reconstruction shows that the orientation relationship in β to α transformation is close to the Burgers orientation relationship but not rational. Besides, the results clearly confirm the orientation inheritance between the reversed β phase and the prior β phase. An accidental finding is that the α boundaries, having with misorientation ranges of 15°–56° and 67°–88°, are nearly identical to the high-angle grain boundaries of prior β phase. This can be a simple approach to identify high-angle grain boundaries of prior β phase when reconstruction algorithm cannot be obtained.