Sustained-Load Crack Growth of 8090 Aluminum-Lithium Alloy Plate in Dry Air at 50-200 C
Abstract
The effects of test temperature, stress-intensity factor, sodium impurity content, and ageing condition on the short-transverse sustained-load (creep) cracking of pre-cracked Al-Li-Cu-Mg-Zr (8090) alloy plate have been studied. Creep cracking was orders of magnitude faster, and threshold stress- intensity factors were much lower, than for conventional aluminium alloys such as 2014-T651. Significant rates of cracking were observed in 8090 alloys at temperatures as low as 60 C. For a given stress-intensity-factor, cracking rates were similar for underaged, peak-aged, and overaged conditions, but were higher for alloys with higher sodium impurity levels. Metallographic and fractographic observations suggest that the presence of liquid, sodium-rich impurity phases promote creep cracking in 8090 alloys. Creep cracking in conventional Al-alloys is probably exacerbated by solid impurity phases such as lead, which are less mobile therefore less damaging than sodium-rich phases. Great Britain.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1990
- Accession Number
- ADA228020
Entities
People
- S. P. Lynch
Organizations
- Royal Aircraft Establishment