Abstract: Wire and arc additive layer manufacturing (WAALM) is a novel manufacturing technique in which metal components can be fabricated layer by layer. In this study, microstructural characteristics of TC4 components after CMT-WAALM deposition were investigated. During arc additive manufacturing process, epitaxial growth of prior columnar β-grain boundaries that were from the high temperature, horizontal stripes, martensite and basket weave microstructures formed due to the heat input, multi heat cycles and cooling rates. The microhardness values at the middle and bottom regions (about 336 HV0.1) were higher, while those at the top regions were significantly decreased (about 323.3 HV0.1).