The Effect of Zr on the High‐Temperature Oxidation Resistance of 12Cr Ferritic/Martensitic Steels

Abstract

The high‐temperature oxidation resistance of 12Cr ferritic/martensitic steels with Zr contents in the range of 0–1.3607 wt% is investigated at 650 and 800 °C in air. The results show that the oxidation resistance of steels is improved by adding Zr. The oxide layer on the surface of steels after oxidation is mainly composed of MnCr2O4 and Cr2O3, where traces of Mn2O3 and ZrO2 oxides can also be detected there. The oxide layer of steels consists of two layers, that is, the outer Mn‐rich oxides (MnCr2O4, Mn2O3) and the inner Cr‐rich oxides (Cr2O3). For none‐Zr steels oxidized at 650 °C, Cr2O3 oxides are also formed in the outer layer. The addition of Zr promotes the outer oxides to change from Cr2O3 oxides to MnCr2O4 oxides and reduces the growth rate of MnCr2O4 oxides. The effect of Zr on the high‐temperature oxidation resistance of steels can be attributed to its promoting effect on the formation of outer Mn‐rich oxides, which can refine the size of outer Mn‐rich oxides and form a dense outer oxide layer. The dense outer oxide layer can inhibit the inward diffusion of oxygen and improve the oxidation resistance of steel.