多段超音波ショットピーニングによるオーステナイト系ステンレス鋼の疲労特性

抄録

The effect of multi-step ultrasonic shot peening (M-USP) on the fatigue characteristics of austenitic stainless steel was investigated. It is known that austenitic stainless steels in the atmosphere are hard to rust because they are covered with a passive film. However, the peening effect on stainless steel has not been well investigated. The test materials are four types of commercially available austenitic alloys SUS304, 304L, 316, 316L. The shot used was a bearing steel ball with a hardness of 800 HV and a diameter of 1, 2, and 3 mm. By M-USP, the surface roughness was reduced and the hardness near the surface was increased. Moreover, as the shot diameter increased, a hardened layer was formed deep inside the material. The fatigue limit of M-USP treatment increased by about 87 MPa compared with that of USP treatment. It was found that M-USP treatment was effective for improving fatigue characteristics.