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Word of the Month - Duralumin, Dural

By Ian Brown, Editor - Bits and Pieces, EAA 657159

In researching the archives for Builders' Tips this month, the author came upon the use of the word "dural". A small amount of reading led him to this description in Wikipedia of an aluminium alloy no longer used but was common 50 years ago.

"Duralumin (also called duraluminum, duraluminium, duralium or dural) is the trade name of one of the earliest types of age-hardenable aluminium alloys. The main alloying constituents are copper, manganese, and magnesium. A commonly used modern equivalent of this alloy type is AA2024, which contains 4.4 percent copper, 1.5 percent magnesium, 0.6 percent manganese and 93.5 percent aluminium by weight. Typical yield strength is 450 MPa (65 ksi), with variations depending on the composition and temper.

Duralumin was developed by the German metallurgist Alfred Wilm at Dürener Metallwerke Aktien Gesellschaft. In 1903, Wilm discovered that after quenching, an aluminium alloy containing 4 percent copper would slowly harden when left at room temperature for several days. Further improvements led to the introduction of duralumin in 1909. The name is obsolete today, mainly used in popular science to describe the Al-Cu alloy system, or 2000 series as designated by the International Alloy Designation System (IADS) originally created in 1970 by the Aluminum Association."

One could imagine that in these days of high-speed production, waiting several days for a material to "age harden" would be problematic.


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