FATIGUE BEHAVIOR OF MOLYBDENUM
Abstract
The objective of the research was to further elucidate the fatigue behavior of commercially pure arc-cast polycrystalline molybdenum; in particular, to investigate the possible relationship between the French damage line and cyclic dependent yield behavior, and to determine coaxing phenomena as a function of grain size. Although the French damage line and the cyclic yield point removal line appear macroscopically similar, the mechanisms proposed for these two phenomena are quite different. The removal of the upper yield point under cyclic stress conditions is explained in terms of localized cumulative multiplication of mobile dislocations, whereas the French damage line is explained in terms of the initiation and propagation of microcracks. Molybdenum, vacuum annealed at 2150 F, 2600 F and 3000 F with resulting ASTM grain sizes of 7-8, 4-5 and 2-3 respectively, was subjected to various coaxing patterns. Using a cycle ratio summation as a criteria, no definite coaxing response pattern occurred for all three molybdenum grain sizes. Cycle ratio summations n/N ranged from .004 to 808. Thus, Molybdenum did respond to coaxing under certain applied stress and cycle increment conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1970
- Accession Number
- AD0709580
Entities
People
- L. L. Frauen
- R. G. Dubensky
- R. I. Stephens
- R. L. Wrenn
Organizations
- University of Iowa