This article explores how post-processing treatments affect the fatigue limit of additive manufactured Ti-6Al-4V in the presence of a stress gradient. Additive manufacturing (AM) technology enables manufacturers to create customized designs that can withstand specific loads, but it often results in complex shapes with stress gradients. Investigation into the influence of microstructure, internal porosity, and surface integrity on the fatigue limit of AM Ti-6Al-4V was conducted. Infrared imaging was used to detect and measure self-heating from which an estimate of the materials fatigue limit was derived. The study indicated that surface integrity is the most important factor to the fatigue life limit, and showed that the infrared thermography analysis provides a quick and accurate way to determine the fatigue limit, compared to the conventional staircase method.