Applied heat input during Directed energy deposition (DED) process can significantly effect both microstructural and mechanical properties of Ti-6Al-4V builds. In order to reveal heat input impact on Additively manufactured (AM) builds,different laser powers, 1500W, 2000W and 3000W are applied to Ti-6Al-4V builds and are investigated through microstructural, and tensile properties. According to the results, changes in power have a significant impact on alpha-lath size and strength properties on the build structures. The relationship analyzed with an employed empirical strength model to unravel underlying working mechanisms such as Hall-Petch, Hardening, Taylor Hardening, Solid solution hardening, and intrinsic strength. The research findings suggest that samples build with high power showed less strain accumulation in the structure, which lowered dislocation density and Taylor hardening, hence impacted the ultimate strength of the build structures. Another finding of this study is α-laths size is coarsened with increased power, that is lowered the Hall-Petch hardening of total strength properties.