Nominal Versus Local Shot-Peening Effects on Fatigue Lifetime in Ti-6Al-2Sn-4Zr-6Mo at Elevated Temperature (Preprint)
Abstract
A study of the elevated temperature fatigue lifetime variability in the shot-peened condition of the a+b titanium alloy, -Ti-6Al-2Sn-4Zr-6Mo, is presented. It is shown that failures separate into two distributions: (1) governed by the nominal residual stress profile, promoting subsurface crack initiation and longer lifetimes, and (2) the life-limiting behavior that is controlled by localized material-shot-peening interaction. In the residual-stress-free condition, failures occurred predominantly by surface crack initiation at the microstructural scale, on the order of 10 um, by crystallographic facet formation in one of a few a particles and/or colonies. This mechanism was mitigated under the nominal shot-peening residual stress profile, producing failures initiating from the subsurface region by crystallographic faceting spread over a significantly larger area (equivalent diameter of about 100-200 um) thank in the absence of residual stress.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2008
- Accession Number
- ADA490187
Entities
People
- James M. Larsen
- R. John
- Sushant K. Jha
Organizations
- Air Force Research Laboratory