Reduction of friction of steel covered with oxide scale in hot forging

The hot ring compression test of chrome steel covered with an oxide scale film is carried out to examine the effects of the oxide scale film on the hot forging characteristics through experiment and finite element analysis. The nominal coefficient of shear friction of the scale is estimated from the plastic deformation behavior of the chrome steel covered with oxide scale film. The estimated coefficient of shear friction of the oxide scale is found to be lower than that of the chrome steel. The plastic deformations and temperature changes of the chrome steel workpiece and the oxide scale layer are calculated using finite element analysis method to investigate the mechanism underlying the reduction in the friction during the hot forging of chrome steel covered with an oxide scale film. Low friction and thermal conductivity values of the oxide scale lead to low forging load in the hot forging of chrome steel covered with an oxide scale film.