TIGHAR
Amelia Earhart Search Forum => Artifact Analysis => Topic started by: Martin X. Moleski, SJ on March 13, 2011, 06:49:12 AM
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Walter Runck suggested that the Forum might be interested in a historic document about the development of ALCLAD:
A L C L A D : new corrosion resistant aluminum product. (http://naca.central.cranfield.ac.uk/reports/1927/naca-tn-259.pdf) E. H. Dix, Jr., Aug 1927.
"Described here is a new corrosion resistant aluminum product which is markedly superior to the present strong alloys. Its use should result in greatly increased life of a structural part. Alclad is a heat-treated aluminum, copper, manganese, magnesium alloy that has the corrosion resistance of pure metal at the surface and the strength of the strong alloy underneath. Of particular importance is the thorough character of the union between the alloy and the pure aluminum. Preliminary results of salt spray tests (24 weeks of exposure) show changes in tensile strength and elongation of Alclad 17ST, when any occurred, to be so small as to be well within the limits of experimental error. Some surface corrosion of the pure metal had taken place, but not enough to cause the specimens to break through those areas."
Spec sheet from Alcoa for 2024 (the ham in a 1937 ALCLAD sandwich). (http://www.alcoa.com/aerospace/en/products/product.asp?market_cat_id=347&prod_id=595) Basic 2024 chemistry + different tempering = different properties.