Aluminum Alloy 8090-T8771 Thick Plate Material Characterization
Abstract
The purpose of this study was to evaluate the mechanical properties of Al-Li alloy 8090, 1.750 inch, thick plate thermally processed to the T8771 condition. Room temperature properties evaluated were: tensile, compression, bearing, and shear strengths, fracture toughness, notched and smooth fatigue, constant amplitude and variable amplitude fatigue crack growth rate. Constant amplitude fatigue crack growth rate test data was generated at two load-ratios, 0.1 and 0.33, and in both laboratory air and saturated air environments. As expected, tensile properties were acceptable for the various specimens orientations removed from the plate's rolling plane: there was a significant drop in yield strength for in-plane specimens oriented 45 degrees off the rolling direction. Also, through-the-thickness ductility was quite low. Compression, bearing, shear and fatigue properties were all good for the specimen orientations examined. The fracture toughness was acceptable for specimens with a L-T and T-L orientations: for through-the-thickness loading, i. e. S-L orientation, the toughness was cut in half. The material showed superior fatigue crack resistance attributable to considerable crack closure induced by very course crack faces. The exceptional surface roughness is characteristic of a mostly unrecrystallized grain structure in Al-Li materials. The high level of closure is manifested as a plateau of nearly constant fatigue crack growth rate over the normally linear log-da/dN versus log delta K mid-range seen in conventional high strength aluminum products and AL-LI materials having a recrystallized grain structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1993
- Accession Number
- ADA274146
Entities
People
- Russell R. Cervay
Organizations
- University of Dayton