STRESS CORROSION CRACKING OF AN ALUMINUM-LITHIUM ALLOY

PDF

Authors
  1. Lenard, D.R.
  2. Starratt, D.L.
Corporate Authors
Defence Research Establishment Pacific, Victoria BC (CAN)
Abstract
The breaking load method was used to evaluate the susceptibility of the aluminium-lithium alloy, AA 8090-T8771, to stress corrosion cracking when exposed to alternate immersion in sea water. The performance of this alloy was compared with that of a conventional aluminium alloy, AA 7075-T651. The original test method showed that both alloys were susceptible to stress corrosion cracking, with threshold stresses close to zero. The method also indicated that both alloys were weakened by a degradation mechanism that occured in the absence of an externally-applied stress. Microscopic examination showed that the weakening was caused by intergranular cracking. The extreme value distribution was found to provide a reasonably good fit to the data, but its use did give rise to several problems previously noted in an interlaboratory test program. The procedure involving Box-Cox transformations did alleviate these problems and served to confirm the conclusions reached using the original method, even though the statistical calculations may not have been strictly valid. Analysis of variance of the transformed data showed that there was no significant difference in the overall behaviour of AA 8090-T8771 and AA 7075-T651 when exposed to alternate immersion in sea water at several different stress levels for several different lengths of exposure. TRUNCATED.
Report Number
DREP-TM-95-11 — Technical Memorandum
Date of publication
01 Mar 1995
Number of Pages
33
DSTKIM No
95-03774
CANDIS No
150985
Format(s):
Document Image stored on Optical Disk;Hardcopy

Permanent link

Document 1 of 1

Date modified: