Effect of Chromium Content on Anodic Polarization Characteristics of Fe-Cr-Al and Fe-Cr-Si Alloys

Abstract The effect of Cr, Al, and Si on the anodic polarization characteristics of Fe-Cr alloys was studied, with Cr content ranging from 10% to 18% in sulfuric acid (H2SO4) and sodium chloride (NaCl) aqueous solutions. It was shown that the effect of Al depended on Cr content while the beneficial effect of Si was found to be independent of Cr content in the Fe-Cr alloys studied. In Fe-Cr-3%Al alloys, the critical current density for passivation and the passive current density decreased as Cr content was increased up to 16%, but these values increased in the Fe-18%Cr alloy. The pitting potential moved in the noble direction when 3% Al was added to the Fe-12%Cr alloy. The pitting potential, however, moved in a less noble direction in Fe-16%Cr and Fe-18%Cr alloys with the addition of 3% Al. The addition of 1% Si helped improve the pitting corrosion resistance of Fe-Cr-3%Al alloys. The repassivation potential of crevice corrosion of Fe-Cr-3%Al alloys was higher than that of Fe-Cr alloys up to a Cr content o...