THE ROLE OF DISLOCATIONS IN THE STRESS-CORROSION CRACKING OF ALUMINUM ALLOYS
Abstract
A thin-film examination of plastically deformed 7075-T6 and -T73 has shown that slip is confined to a smaller number of planes in the -T6 than in the -T73. X-ray line broadening measurements of (MgZn2) particle size in a series of overaged 7075 conditions, together with stress-corrosion and tensile tests, have indicated that a correlation exists between particle size, time-to-failure, and yield strength. Each of these quantities undergoes a rapid change during the first 10 hours of aging at 350 F, and a much slower change thereafter. In cryogenic tensile tests, the yield strengths of -T6 and -T73 were shown to have a similar temperature dependence: the T2/3 dependence, which is suggestive of a shearing mechanism, was obeyed from 20 to 160 K, and a smaller dependence was exhibited from 160 to 300 K. Dislocation mobility measurements have demonstrated a higher strain-rate sensitivity in -T6 than in -T73, and also a stronger tendency toward strain aging in the former temper. Amplitude-dependent internal friction studies have provided insight into dislocation-precipitate interactions, as well as into the early aging process in 7075.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1968
- Accession Number
- AD0833543
Entities
People
- A. J. Jacobs