The Delayed Fracture of Aluminum Alloys.
Abstract
The relationship between susceptibility to stress-corrosion cracking (SCC) and grain boundary (GB) chemistry was investigated in an attempt to elucidate the SCC mechanism in aluminum-zinc-magnesium alloys. Research was performed in two phases: (1) develop a method for inducing intergranular fracture on the actual grain boundary to enable measurement of GB composite by Auger electron spectroscopy (AES) and (2) attempt to relate changes in GB composition to changes in SCC susceptibility. The three methods of inducing intergranular fracture were evaluated: (1) fracture at near-liquid nitrogen temperatures, (2) fracture after pre-exposure to liquid gallium, and (3) fracture after pre-exposure to water vapor-saturated air (WVSA). Fracture after pre-exposure to WVSA (i.e., hydrogen pre-exposure embrittlement: H-PEE) is brittle intergranular and no reaction occurred with the fracture surface, thereby allowing composition to be measured by AES. The H-PEE fracture technique was then used to measure GB compositions for an alloy whose SCC susceptibility was varied by changing either solution heat-treatment temperature (SHT) or aging time. Keywords: Aluminum alloys, Stress-corrosion cracking, Intergranular fracture, Grain boundary segregation, Liquid metal embrittlement, Hydrogen embrittlement, Fracture at cryogenic temperatures, Auger electron spectroscopy, Aging, Solution heat treatment.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1985
- Accession Number
- ADA165203
Entities
People
- Joseph R. Pickens
- Timothy J. Langan
Organizations
- Martin Marietta