Owing to the high cooling rates and thermal gradients, additive manufacturing (AM) of metals results in the formation of hierarchical microstructures such as melt pools, grains, cellular/dendritic structures, and copious amounts of dislocations. These features govern the complex layer-wise solidification within a melt pool and epitaxial growth of grains between layers which results in the formation of potentially strong textures. In this work, we use laser powder bed fusion (LPBF) technique to produce two in-situ alloyed β Ti-Nb alloys (bcc crystal structure) with differing textures i.e., a <100> cube texture and a near random texture. We use our newly designed, fully automated 3D electron backscattered diffraction (EBSD) system, ELAVO 3D, to understand the complex solidification and grain selection mechanisms within the 3D volume of a melt pool that eventually results in the texture of the bulk part. We display and analyze the results from the ELAVO 3D investigations by using the in-house version of QUBE software. We also identify the role of inclusions in obstructing the epitaxial growth of grains. The results from this work provide insights to advance the current knowledge on texture formation mechanisms in metal AM.