Spectrum Fatigue Crack Growth Rate Characteristics of PM (Powder Metallurgy) Aluminums 7090 and 7091
Abstract
Fatigue crack growth rate testing was performed on powder-metallurgy (PM) produced aluminum 7090 and 7091. Forms examined for each alloy were plate, extrusions, and hand forgings. Crack growth properties for each material were evaluated using both a fighter aircraft-type spectrum (FALSTAFF) and a transport-type aircraft spectrum (Mini-TWIST). All results are compared to ingot-metallurgy (IM) produced aluminum 7050-T76 plate. Results under spectrum loading conditions indicate the PM 7091 alloys are consistently superior to aluminum 7050 in terms of spectrum fatigue crack growth resistance, while the 7090 alloys were clearly inferior. The best PM alloy in terms of crack growth resistance was 7091-T7E69 extrusion; the worst was the 7090-T7E80 forging. Though an improvement in crack growth resistance was observed for the 7091 materials over 7050 under complex loading, constant amplitude crack growth rates for both 7090 and 7091 are considerably greater than that for 7050. These apparent conflicting results are believed to be a result of beneficial load interactions (crack retardation) for the 7091 materials occurring during complex loading. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1983
- Accession Number
- ADA129846
Entities
People
- John J. Ruschau
Organizations
- University of Dayton