Duralumin
Duralumin (also called
duraluminum,
duraluminium or
dural) is the 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 (in wt.%) 4.4%
copper, 1.5%
magnesium and 0.6%
manganese. Typical
yield strength is 450 MPa, with variations depending on the composition and
temper[ASM Handbook. Volume 2, In Properties and Selection: Nonferrous alloys and special purpose materials. ASM, 2002.].
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% Cu would slowly harden when left at room temperature for several days. Further improvements led to the introduction of Duralumin in 1909
[J. Dwight. Aluminium Design and Construction. Routledge, 1999.]. The name is today obsolete, and mainly used in
popular science to describe the Al-Cu alloy system, or 2000 series as designated by the
Aluminum Association.
Its first use was rigid
airship frames. Its composition and heat-treatment were a wartime secret. With this new rip-resistant mixture, duralumin quickly spread throughout the
aircraft industry in the early 1930s, where it was well suited to the new
monocoque construction techniques that were being introduced at the same time. Duralumin also is popular for use in precision tools such as levels because of its light weight and strength.
Although the addition of copper improves strength, it also makes these alloys susceptible to
corrosion. For sheet products, corrosion resistance can be greatly enhanced by metallurgical bonding of a high-purity aluminium surface layer. These sheets are referred to as
Alclad, and are commonly used by the
aircraft industry
[J. Snodgrass and J. Moran. Corrosion Resistance of Aluminum Alloys. In Corrosion: Fundamentals, Testing and Protection, volume 13a of ASM Handbook. ASM, 2003.].
List of typical uses for the
wrought Al-Cu alloys
[:]
* 2011: Wire, rod, and bar for screw machine products. Applications where good machinability and good strength are required.
* 2014: Heavy-duty forgings, plate, and extrusions for aircraft fittings, wheels, and major structural components, space booster tankage and structure, truck frame and suspension components. Applications requiring high strength and hardness including service at elevated temperatures.
* 2024: Aircraft structures, rivets, hardware, truck wheels, screw machine products, and other miscellaneous structural applications.
* 2036: Sheet for auto body panels.
* 2048: Sheet and plate in structural components for aerospace application and military equipment.
* 2141: Plate in thicknesses of 40 to 150 mm (1.5 to 6.0 in.) for aircraft structures.
* 2218: Forgings; aircraft and diesel engine pistons; aircraft engine cylinder heads; jet engine impellers and compressor rings.
* 2219: Welded space booster oxidizer and fuel tanks, supersonic aircraft skin and structure components. Readily weldable and useful for applications over temperature range of -270 to 300 °C (-450 to 600 °F). Has high fracture toughness, and the T8 temper is highly resistant to stress-corrosion cracking.
* 2618: Die and hand forgings. Pistons and rotating aircraft engine parts for operation at elevated temperatures. Tire molds.*Fictional applications of real materials
