Effect of ultrasonic rolling strengthening on the bending fatigue
characteristic of 12Cr2Ni4A steel gear
Abstract
To improve the bending fatigue life of gears, a novelty method of the
ultrasonic rolling strengthening is proposed to process tooth roots of
the spur cylindrical gears . The variations in the residual stress,
surface hardness and the depth of hardened layer of the tooth root were
studied. Subsequently, the bending fatigue experiments of the single
tooth were performed, and the relationship among the surface residual
stress σ, surface hardness Hv, the depth of the hardened layer δ and the
bending fatigue life was investigated. The results exhibit that the
tensile residual stress located on the tooth roots is converted to the
residual compressive stress. Compared with the unreinforced condition,
the bending fatigue strength of the strengthened gears is increased by 2
times, and its fatigue life is extended by 15 times.