a ball bearing for use in a high - temperature , high - speed , light - load environment is proposed which includes inner and outer rings formed of heat - resistant bearing steel m50 . a nitrided layer which is formed of a diffusion layer only is formed on each of the surfaces of the inner and outer rings where the raceways are formed . a chromium nitride film is further formed on the nitrided layer . the layer and film serves to prevent surface - starting peeling and smearing , thus prolonging the life of the bearing .