Effects of Mn addition on oxidation behaviour of heat-resistant steel in a high-temperature steam environment

A comparative study of high chromium (Super304H) and high manganese low chromium heat-resistant steel (HT630) was carried out at 650°C in steam. Results indicate that the high manganese content in HT630 significantly improved its oxidation resistance. It is ascribed to the formation of a dense protective MnCr2O4 oxide layer during oxidation. MnCr2O4 layer effectively inhibits the diffusion of iron, suppresses the growth of iron-rich oxides, promotes the formation of an iron-rich protective interface with the matrix, and improves the overall oxidation resistance.