Accession Number:

ADA129846

Title:

Spectrum Fatigue Crack Growth Rate Characteristics of PM (Powder Metallurgy) Aluminums 7090 and 7091

Descriptive Note:

Interim technical rept. Jul 82-Jan 83,

Corporate Author:

DAYTON UNIV OH RESEARCH INST

Personal Author(s):

Report Date:

1983-04-01

Pagination or Media Count:

38.0

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

Subject Categories:

  • Metallurgy and Metallography
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE