First-principles study on pitting corrosion of Al deoxidation stainless steel with rare earth element (La) treatment

Abstract

In this work, the first-principles calculation is employed to study the pitting corrosion of Al deoxidation steel with rare earth element (La) treatment. Firstly, we compare the calculation results using GGA-PBE and LDA functions to experimental phenomena. The results indicate that PBE function is suitable for subsequent calculations. And then we find that, for different inclusions, the mechanisms of improving corrosion resistance by doping rare earth element (La) are different. The Cr oxide is modified into Al oxide, which is an important reason that the addition of La improves the corrosion resistance of Cr2O3. Both Al2O3 and LaAlO3 inclusions show poor conductivity due to their relatively wide band gap structures. The microcrevices is an important reason that induces the pitting corrosion. The LaAlO3 inclusion shows relatively excellent corrosion resistance compared to Al2O3 due to the reduction of microcrevices. Inclusion clusters including MnS have a greater effect on corrosion properties than single inclusions. In addition, the doping of La element refining inclusions size is an important and common reason that improves resistance to corrosion properties of microalloyed steels.