Accession Number : ADA132928

Title :   Fatigue Crack Growth Rates of High-Magnesium Aluminum-Magnesium Alloys as Influenced by Solution Treatment Time and Alloy Content.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Oberhofer,Kurt D

PDF Url : ADA132928

Report Date : Jun 1983

Pagination or Media Count : 69

Abstract : Test equipment was fabricated and fatigue crack propagation data were obtained for aluminum alloy 7075-T6 and for thermomechanically processed A1-10.2 Wt Pct Mg-0.52 Wt Pct Mn, and A1-8.14 Wt Pct Mg-0.40 Wt Pct Cu alloys. The crack growth data and fractographic information obtained for the 7075-T6 alloy were consistent with data in the literature. The manganese containing alloy was solution treated for nine and twenty-five hour periods. Observed was a decrease in the fatigue crack growth resistance for the longer solutioning time, which appears to be due to the formation and coarsening of Mn A16 precipitates which fail to dissolve in solution treatment during thermomechanical processing. The copper containing alloy exhibited better crack growth resistance than the 7075-T6 alloy. This alloy has a more diffuse cell structure, relatively little precipitated Mg5A18, and no constituent particles associated with cell of grain boundaries. (Author)

Descriptors :   *Magnesium alloys, *Aluminum alloys, Crack propagation, Grain boundaries, Fatigue(Mechanics), Stresses, Thermomechanics, Copper alloys, Electron microscopy, Theses

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE