The development of non-destructive and non-contact techniques for evaluating metallic materials represents a great value in the metal characterization field. These techniques have a significant advantage over the traditional material characterization and sometimes, they are used to monitor industrial or in-lab processes in real time. Infrared photocarrier radiometry (PCR) has not been widely used to characterize metals, especially steels. In the case of metals such as carbon steel, thermal and electrical properties depend on the electron excitation movement. PCR images were obtained through thermal changes analyses of different carbon content steels. PCR amplitude and phase images were used to analyze thermal changes, in order to explain the relationship between the PCR signal and the carbon content of steel samples. An X-ray diffraction (XRD) analysis was also used to characterize structural changes produced in steel samples. Full width at the haft medium (FWHM) changes of each peak, as well as peak shifts were used to evaluate the crystalline quality after the annealing heat treatment.