Nondestructive Evaluation of Metal Fatigue.
SOUTHWEST RESEARCH INST SAN ANTONIO TEX DEPT OF INSTRUMENTATION RESEARCH
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The important role of nondestructive evaluation NDE methods in complementing the tools of fracture mechanics for preventing catastrophic fatigue failures in engineering structures is discussed. Magnetic perturbation signatures from surface and subsurface fatigue cracks in AISI 4340 steel rod-type axially loaded specimens are illustrated, compared, and considered in terms of the plastic zone and residual stresses in the vicinity of the fatigue cracks. Also, magnetic records from drilled holes and fatigue cracks in 4340 and maraging steels are presented which show significant differences in response from the two materials. Preliminary acoustic emission investigations on rod-type specimens containing surface fatigue cracks are reviewed and the results compared with those from single edge-notched flat specimens. Author
- Metallurgy and Metallography
- Test Facilities, Equipment and Methods