Effects of Hot Dip Aluminizing and High Temperature Oxidation Process on Surface Microstructure of TWIP Steel

Al₂O₃ film was prepared on TWIP steel by hot-dip aluminizing,annealing and high temperature oxidation.The effects of process parameters and low oxygen pressure on the formation of coating and oxidation structure were studied.The morphologies of the coating and oxide film were observed by scanning electron microscope,and the phase was determined by energy dispersive spectrometer and X-ray photoelectron spectroscopy.The results show that the higher the temperature,the thicker the FeAl₃ diffusion layer.When the coated samples are annealled in vacuum at 900℃for 5 h,the FeAl₃ phase in the initial coating is transformed into FeAl phase with better toughness.With further oxidation,the oxide film appears on the surface of the sample,and the oxide film formed under low oxygen pressure is smoother and denser.XPS analysis shows that the oxide film is Al₂O₃ film.