Effect of rare earths on oxidation resistance of heat resistant steel

The application of rare earths (RE) in the Ni saving heat resistant steel was studied by metalloscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray difference (XRD). Because the diffusion of chromium was promoted by RE, a dense and adhesive Cr2O3 layer could form rapidly at the early oxidation stage, which played a effective protection role; the pinning effect of silicon dioxide was enhanced by RE in the internal oxidation layer, which had a block effect on the diffusion of metal ions and oxygen ions at later stage of oxidation and resulted in that the high temperature oxidation rate of RE heat resistant steel was decreased.