In order to determine the influence of matrix structure on the corrosion rate of spheroidal graphite cast iron, a corrosion test was performed in sulfuric acid solution of pH 2. The pearlite matrix area was changed by heat treatment. The corrosivity of spheroidal graphite cast iron was evaluated by corrosion potential, corrosion rate and observation of the surface of the specimens by SEM. Ferrite in the lamellar structure of pearlite dissolved preferentially. The corrosion rate of the pearlite matrix was higher than that of ferrite. The corrosion potential became less noble with the increase of the prarlite area. These results indicate that the increase of pearlite promotes both cathodic and anodic reactions.
