Effect of Alloying Elements on Corrosion Resistance of Foundry Fe-Cr Ferritic Stainless Steels in Concentrated Sulfuric Acid

The effects of alloying elements on the corrosion behavior of foundry Fe-Cr ferritic stainless steels in concentrated sulfuric acid were studied by electrochemical techniques, immersion corrosion and energy dispersive spectroscopy (EDS). The results show that the corrosion resistance of Fe-Cr alloys in concentrated sulfuric acid improved with the increase of Cr content. However, the single Cr alloyed Fe-Cr alloy was unable to reach self-passivation in 98% H₂SO₄ at 60℃. Mo addition enhanced the corrosion resistance and promoted the passivation and self-passivaiton of Fe-Cr25-Mo alloys. Elements Ni and Cu can also promoted the passivation and self-passivation of Fe-Cr25Mo2 alloys, whereas Ti and Nb only had a little influence on the passivation.