The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate‐type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25‐μm deep surface pit produced by an electrospark machine. The importance of studying these cracks which closely approximate naturally occurring fatigue cracks is briefly discussed.

Topics
Materials degradation, Crack initiation and detection
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© 1985 American Institute of Physics.
1985
American Institute of Physics
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