Exploratory Development Studies for Sustained Load Subcritical Crack Growth in Titanium Alloys
Abstract
The following conclusions seem appropriate: The internal hydrogen level of a titanium alloy may increase the sustained load cracking behavior of the material; The extent of this degradation is dependent upon the microstructure, environment and, possibly, short range order. Other submicrostructural features may also be involved; Materials with an alpha + beta microstructure seem to show a greater susceptibility to sustained load cracking and hydrogen level than do the beta processed materials; As the thickness and associated triaxial constraint decrease, the tendency to exhibit sustained load cracking in high humidity air and dry argon decrease for Ti-6Al-4V(RA) with a high hydrogen content; Crystallographic texture in the Ti-6Al-4V(RA) does not appear to exhibit a major influence on sustained load cracking in high humidity air or dry argon but does exhibit a major effect in 3 1/2% NaCl solution; Great care must be exercised in assessing sustained load cracking behavior of Ti alloys since crack tip branching can result in crack arrest at a level much above that level where extensive sustained load cracking occurs. No single model for sustained load cracking appears to predict all of the observed sustained load cracking behavior. Rather it appears to involve a combination of effects involving internal hydrogen, creep and environmental parameters which may not always be of a detrimental nature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1977
- Accession Number
- ADA054270
Entities
People
- D. E. Pettit
Organizations
- Lockheed Martin