Title
Long-term outdoor stress corrosion testing of overaged 7000 series aluminium alloys
Author
Schra, L.
't Hart, W.G.J.
Institution
National Aerospace Laboratory NLR
Date
1988-01-31
Abstract
Long-term outdoor stress corrosion tests were executed on overaged 7000 series aluminium alloy plate and forgings. Plate material of the alloys 7010-T7651, 7010-T7451 and 7075-T7351 exhibited an excellent resistance to SCC. PM alloy X7091-T7E69 forgings combined a higher strength with superior SCC resistance as compared to IM alloy forgings. The SCC resistance of forgings of the alloys 7075-T73 and 7050-T74 was substantially better than that of forgings of the alloys 7175-T74, 7010-T74 and AZ74.61. When strength was taken into account only the SCC propagation resistance of 7010-T74 was clearly inferior to that of the other alloys. Accelerated laboratory tests did not always enable a correct prediction of the SCC resistance; this emphasizes the importance of verification of laboratory tests by testing in a more realistic environment, especially for classification of new materials. SCC growth was affected by corrosion product wedging which may also occur in aircraft structures and complicates prediction of SCC growth.
Subject
High strength alloys
Aluminium alloys
Stress corrosion cracking
Forgings
Metal plates
Exposure
Corrosion tests
Transgranular corrosion
Accelerated life tests
Corrosion resistance
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Publisher
Nationaal Lucht- en Ruimtevaartlaboratorium
Access restriction
Campus only
Source
NLR-TR 88012 U
Part of collection
Aerospace Engineering Reports
Document type
report
Rights
(c)1988 National Aerospace Laboratory NLR