Fundamental aspects of AE monitoring on corrosion fatigue processes in austenitic stainless steel

It has been shown that AE activity during crack growth is related to the stress state in the crack tip plastic zone. It is known that the maximum stress in the plane strain plastic zone can be as high as three times the uniaxial yield stress because of the plastic constraint. Because the effective yield stress in plane strain is much larger than the uniaxial yield stress, higher AE activity is expected from a crack growing under plane strain conditions than from one growing under plane stress. This aspect is observed for a 304 austenitic stainless steel in the present study.