マイクロショットピーニングを施したチタン合金の疲労特性

抄録

The effect of microshot peening on the surface hardness and fatigue strength of titanium alloy was investigated. Shot peening is a widely used surface treatment method for improving fatigue life. This process imparts compressive residual stresses on the surface, thus improving the fatigue life of the machine parts. In the peening process, the equipment were used an air-type machine and ultrasonic peening machine. The microshot used were high-carbon cast steel with an average diameter of 0.1mm. The surface hardness data showed that, in the case of microshot peening, work hardening extended deeper than the mean diameter of the media. In addition, in the case of ultrasonic peening, the surface hardness increased slowly with the projection time. The rotary bending fatigue tests were carried at a frequency of 3150 cycles/min. Improvement of the fatigue strength was observed by both treatments. The higher effect was found in the ultrasonic peening treatment, because a work-hardened layer was formed deeper in the material.