The purpose of this study is to develop an innovative non-destructive methodology for analyzing the thermal effects in metallic materials caused by fatigue. Mechanical stresses induced by cyclic loading in the material cause heat release due to microstructural changes, which results in an increase of the material's temperature. The heat release was quantified as a function of fatigue cycles in carbon steel samples. Mechanical hysteresis phenomena were analyzed to identify the metrics of damage, which relates to thermal parameters characterizing the level of damage of the material as a function of fatigue cycles.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.