Abstract 

A steel frame installed in a metallurgical plant, subjected to prolonged temperature exposure, presented distortion, cracking and oxidation at areas that could compromise its structural integrity. Further assessment of mechanical properties indicated an acute reduction of tensile strength up to 33%. Metallurgical examination revealed significant microstructural degradation involving cementite spheroidization and graphite formation due to carbon diffusion and coalescence that caused softening. Fractographic evaluation addressed the fracture mechanisms in damaged and unaffected areas, which supported the previously stated differences in mechanical properties, as a result of thermal deterioration processes occurred during service in industrial furnace conditions.