High-Temperature Oxidation Behaviors of 321 Steel with Y or Nb Micro-Alloying

Abstract

The effects of Y or Nb addition on the oxidation behavior of 321 steel at high temperatures were investigated by scanning electron microscopy (SEM), energy spectroscopy (EDS) and X-ray diffractometer (XRD). At the same time, the oxidation mechanism and oxidation kinetics of rare earth Y or Nb addition are explored. The results show that temperature greatly influences the high-temperature oxidation resistance of the alloys, and the oxidation phenomenon of the alloy becomes more obvious as the temperature increases. Adding 0.5 wt.% Nb or 0.045 wt.% Y elements can effectively improve the oxidation resistance of 321 stainless steel at high temperatures. The addition of rare earth Y can promote the diffusion of Cr in the matrix, leading to increased Cr content in the oxide film and the eventual formation of a dense Cr2O3 film, which effectively hinders the continuation of the oxidation reaction. As a result of the Nb addition, the outward diffusion of Cr elements can be effectively inhibited, Cr and O ion bond can be strengthened, the oxidation rate can be reduced, the adhesion rate of oxide film can be increased, and the oxidation resistance of 321 stainless steel can be improved.