Samples of ASTM A53 steel grade B underwent 500 oxidation cycles at 600°C. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) were performed to study the morphology, composition and phase structure of Fe2O3 y Fe3O4 layers on oxidation surface. Such layers were homogenous and poorly adhesive. Mass loss was significant due to absence of protective oxides and inevitable flaking, leaving the substrate exposed to corrosive environment.