Effect of Shakedown on the Fatigue Limit of Ultrasonic Shot Peened Steel

摘要

We performed in-plane bending fatigue tests under controlled load conditions on ASTM 309 stainless steel specimens with surface compressive residual stress. The results provide a fatigue limit of 415 MPa, which agrees with the value of 404 MPa calculated based on a modified Goodman line considering shakedown. Therefore, the surface layer was clearly restricted by the internal bulk and was relieved under controlled displacement, after which shakedown occurred. Then, the fatigue limit of the metal material with surface compressive residual stress should be estimated by using a modified Goodman line considering shakedown to avoid unexpected fractures that could occur by following a modified Goodman line that does not consider shakedown.