Nondestructive Evaluation of Metal Fatigue.
Abstract
The role of those nondestructive evaluation (NDE) methods that can provide quantitative information about fatigue cracks to aid in the fracture mechanics determination of crack 'state' is discussed. The qualitative characteristics of magnetic perturbation signatures from fatigue cracks in 4340 steel specimens which provide the bases for recent investigations are summarized. The results of the recent experiments involving the effects of post-crack heat treatments and probe orientations on crack signature characteristics are presented and discussed. While the significant signature characteristics do not appear to relate directly to certain physical features of fatigue cracks of interest, there is evidence that the magnetic signatures can provide quantitative information about the 'state' of a fatigue crack. Limited investigations of approaches to improve the detection of fatigue cracks in Ti-6Al-4V alloy using ultrasonic surface wave and electric current injection methods are described and the results summarized. Metallurgical sectioning efforts were continued in the vicinity of inclusions with fatigue cracks in the early stages of development and the results support a model for the early stages of fatigue crack development which can explain the occurrence of nonpropagating cracks. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1974
- Accession Number
- AD0780092
Entities
People
- F. N. Kusenberger
- J. Lankford Jr.
- Joshua R. Barton
- Philip H. Francis
- W. L. Ko
Organizations
- Southwest Research Institute