LAUSR

ABSTRACT The notched U75V steel specimen was treated by a special way called bearing ultrasonic peening on the base of traditional ultrasonic peening. The bearing ultrasonic peening means that ultrasonic peening was applied after fatigue static load was imposed. Severe plastic deformation and work hardened layer were produced in the notched surface. The effect of compressive residual stress induced by ultrasonic peening treatment on fatigue properties was deeply analysed. Results showed that the depth of work hardened layer is around 90 μm and the hardness value of the treated surface is about 1.7 times of base material. Fatigue strength corresponding to 107 cycles of as-notched specimens treated by traditional ultrasonic peening and bearing ultrasonic peening was improved by 71.9 and 81.8%, respectively. The lasting high compressive residual stress during fatigue tests is the main reason of fatigue life improvement for as-notched specimens treated by bearing ultrasonic peening.