27th IFHTSE CONGRESS & EUROPEAN CONFERENCE ON HEAT TREATMENT 2022

Steel rebars are widely applied in the construction field. They are combined with concrete to obtain one of the most used construction composite material: reinforced concrete. The steels are responsible for the high tensile properties. In special chemical environments they suffer from corrosion. With low pH’s caused by carbonation they exhibit uniform corrosion, while in the presence of NaCl salts they show localized corrosion, which in turn may have detrimental effects on the rebar sections. The properties of steels can be modified by several thermal treatments. The corrosion resistance may also be affected by the temperature. Changes on the surface and in the microstructure takes place. In this work a conventional rebar B 500 type with a diameter of 12 mm is exposed to shock heat treatments with the temperature ranging between 900 oC to 1400 oC for a time period between 5 minutes to 120 minutes and water quenched. Hardness measurements were carried out to evaluate the local changes from the surface to the interior of the rebar and the related modification of the microstructure. The specimens were subsequently exposed to a 10 wt. % HCl solution up to 30 days to determine the intensity of the localized corrosion phenomena. The changes in the microstructure and in the corrosion properties of the rebars were investigated by means of visual inspection, optical microscopy and scanning electron microscopy with EDAX.