Crack closure and crack growth behaviour in shot peened fatigued specimen

摘要

Fatigue crack propagation behaviour after shot peening was investigated in compact tension specimens of AISI 304 stainless steel. The test specimens were exposed. to shot stream at Almen intensity of 12C on the specified regions of both sidesurfaces. These regions were located behind, around. and ahead of the fatigue crack tip as well as adjacent to the starter notch Subsequently, re-initiation life, propagation rate, closure level and the resulting crack growth retardation were studied.Both crack closure and the attendant growth retardation were shown. from the, experimental observations to be dependent on the location of peened regions. Closure effect was stronger in the case of peening process behind the crack tip, and an order of upto 560,000 cycles was assigned for an extension of the specimen life.