Microcrack propagation in Ti-6Al-4V alloys
In this study, microcrack propagation in Ti-6Al-4V was examined in regions just above and below the fatigue limit. Two different Ti-6Al-4V alloys with nominally similar chemical compositions were examined: the first alloy was thermo-mechanically treated in the laboratory to develop a bi-modal and a fully lamellar microstructure and the second alloy is from the High Cycle Fatigue MURI program (forging No. 197) containing a duplex microstructure. Microcracks were nucleated in smooth specimens of each microstructure in the LCF regime during tests conducted at R = {minus}1 (R = {sigma}{sub min}/{sigma}{sub max}) so that internal stresses could be minimized. These samples were then tested in the HCF regime to determine crack propagation rates for R values of {minus}1, 0.1, and 0.5. In addition, conventional fatigue crack propagation curves for macrocracks using CT-specimens were measured. Comparisons in microcrack growth behavior were evaluated and discussed for the bi-modal and fully lamellar microstructures, for bi-modal and forging No. 197 microstructures, and for forging No. 197 examining the influence of R = 0.1 and 0.5. Much of the observed behavior appeared to be explained by differences in crack front roughness.
- Research Organization:
- Technical Univ. Hamburg-Harburg (DE)
- OSTI ID:
- 20013303
- Resource Relation:
- Conference: TMS Fall Meeting '98, Symposium on Fatigue Behavior of Titanium Alloys, Chicago, IL (US), 10/11/1998--10/15/1998; Other Information: PBD: 1999; Related Information: In: Fatigue behavior of titanium alloys, by Boyer, R.R.; Eylon, D.; Luetjering, G. [eds.], 382 pages.
- Country of Publication:
- United States
- Language:
- English
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