c for one hour and then quenching in the oil of 60 u00b0 c and finished by grinding to the surface roughness of about 0 01 u03bcm ra similar inner and outer bearing rings were formed from scm435 and subjected to carbonitriding treatment i e carbonitriding at 850 u00b0 c for eight hours and thereafter quenching in the oil of 60 u00b0 c and tempering at 160 u00b0 c for two hours then only the raceway surfaces of the bearing rings were subjected to shot peening and finished by grinding to the surface roughness of about 0 0 u03bcm ra in the meantime the shot peening was performed by using an air nozzle type shot peening machine and round cut wires of the average particle size of 0 3 to 0 4 mm in diameter and of the hardness of 700 to 800 hv as shots balls and under the condition of the arc height of 0 48 mma and coverage of 300 or more on the other hand similar rollers were formed from suj2 and subjected to refining i e heating at 850 u00b0 c for one hour and thereafter quenching in the oil of 60 u00b0 c and finished.