Determination of Prefracture Fatigue Damage.
Abstract
The dislocation distribution as a function of depth was investigated on fatigued and unidirectionally strained specimens of 4130 steel, 2024 aluminum as well as on single crystals of aluminum and silicon. Using x-ray line broadening together with the Berg-Barrett technique it was shown that the excess dislocation density was much larger in the surface layer to a depth of about 100 micrometres than in the bulk. From the measurements of the initial permeability at high frequencies (10 kilohertz) it would also be inferred that the dislocation density was larger in the surface layer. Because acoustic emissions were found at very low stresses relative to the maximum stress during fatigue, it appears that this method cannot be used on ferromagnetic materials to detect fatigue damage. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1976
- Accession Number
- ADA033484
Entities
People
- David W Taylor
- Irvin R. Kramer