The effect of carbon percent on the corrosion of steel in ethanol – aqueous H₂SO₄ solution has been studied by using weight loss technique. The effect of presence of foreign atoms in steel composition on the corrosion resistance has been investigated. Beside that, the effect of heat treatment on the corrosion rates has been interpreted. The inhibitive action of N, N-dihydroxy ethyl acryl-amide on the corrosion rate of steel appears high efficiency for all samples in all cases under study. The corrosion behavior is interpreted in view of the microstructure of samples before and after heat treatment. There are two wet corrosion processes that affected by carbon percent in the localized area. Before heat treatment the corrosion rate is more dependent upon inter-granular corrosion type while, increasing C % or by quenching regime the corrosion rate is more dependent upon allotropic–galvanic corrosion type. The corrosion rate in absence of inhibitors classified as cathodic control while it classified as cathodic–anodic control in presence of inhibitor.