Influence of Oxide Scale Formed on Chrome Steel Surface in Steam Atmosphere on Deformation Behavior of Chrome Steel in Hot Ring Compression

Hot forging characteristics of chrome steel and carbon steel covered with oxide scale formed in steam atmosphere were investigated with the ring compression test. In oxidation of the steels in steam atmosphere, the oxide scale with high porosity was formed in oxidation of the steels, while the oxide scale with thick FeCr2O4 layer around the oxide scale–chrome steel interface was formed in oxidation of the chrome steel. The nominal coefficient of shear friction of the steels covered with oxide scale was derived from the plastic deformation behavior of the steels covered with oxide scale during the ring compression test. The oxide scale of the chrome steel formed in steam atmosphere provided low friction characteristic, compared with the oxide scale formed in air atmosphere. The mechanism of reduction of friction of the steels covered with oxide scale was discussed from the viewpoints of heat transfer and interfacial friction at oxide scale–chrome steel interface by the experiment and finite element analysis.