Accession Number:

ADA165203

Title:

The Delayed Fracture of Aluminum Alloys.

Descriptive Note:

Final rept.,

Corporate Author:

MARTIN MARIETTA LABS BALTIMORE MD

Personal Author(s):

Report Date:

1985-10-01

Pagination or Media Count:

82.0

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.

Subject Categories:

  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE