THE EFFECTS OF HARD ANODIZING ON THE STRESS CORROSION CRACKING OF ALUMINUM ALLOYS

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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 determine the effects of alternate immersion in sea water on uncoated, sulphuric acid anodized and hard anodized specimens of AA 7075-T651 in order to evaluate the benefits of anodizing the aluminum pressure hull of an autonomous underwater vehicle to reduce the risk of stress corrosion cracking. The original test method showed that anodizing delayed the onset of stress corrosion cracking of specimens subjected to an externally-applied stress of 69 MPa, with hard anodizing providing a greater benefit than sulphuric acid anodizing. Anodizing was also shown to delay the onset of intergranular cracking in the absence of an external stress. The value of the threshold stress determined for the uncoated specimens was within the range reported by an interlaboratory test program. The conclusion was that anodizing provided a significant improvement in resistance to stress corrosion cracking, with hard anodizing providing the greater benefit.
Keywords
AA 7075-7651;BOX-COX TRANSFORMATIONS;AUV (Autonomous Underwater Vehicle)
Report Number
DREP-TM-94-126 — Technical Memorandum
Date of publication
01 Nov 1994
Number of Pages
35
DSTKIM No
95-00062
CANDIS No
148400
Format(s):
Hardcopy;Document Image stored on Optical Disk

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