Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age-hardenable aluminium alloys. The term is a combination of ''

Düren Düren (; ripuarian: Düre) is a town in North Rhine-Westphalia, Germany, between Aachen and Cologne on the river Rur. History Roman era The area of Düren was part of Gallia Belgica, more specifically the territory of the Eburones, a pe ...

er'' and ''aluminium''. Its use as a trade name is obsolete. Today the term mainly refers to aluminium–copper alloys, designated as the 2000 series by the international alloy designation system (IADS), as with

2014 File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...

and 2024 alloys used in airframe fabrication.

History

Duralumin was developed by the German metallurgist

Alfred Wilm Alfred Wilm (25 June 1869 – 6 August 1937) was a German metallurgist who invented the alloy Al-3.5–5.5%Cu-Mg-Mn, now known as Duralumin which is used extensively in aircraft. Whilst working in military research NUTZ in Neubabelsberg in 1901, Wi ...

at Dürener Metallwerke AG. In 1903, Wilm discovered that after

quenching In materials science, quenching is the rapid cooling of a workpiece in water, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as ...

, an aluminium alloy containing 4% copper would harden when left at room temperature for several days. Further improvements led to the introduction of duralumin in 1909. The name is mainly used in pop-science to describe all Al-Cu alloys system, or '2000' series, as designated through the international alloy designation system originally created in 1970 by the Aluminum Association.

Composition

In addition to

aluminium Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...

, the main materials in duralumin are

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...

, manganese and magnesium. For instance, Duraluminium 2024 consists of 91-95% aluminium, 3.8-4.9% copper, 1.2-1.8% magnesium, 0.3-0.9% manganese, <0.5% iron, <0.5% silicon, <0.25% zinc, <0.15% titanium, <0.10% chromium and no more than 0.15% of other elements together. Although the addition of copper improves strength, it also makes these alloys susceptible to

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

. Corrosion resistance can be greatly enhanced by the metallurgical bonding of a high-purity aluminium surface layer, referred to as alclad-duralum. Alclad materials are commonly used in the aircraft industry to this day.

Applications

Aluminium alloyed with copper (Al-Cu alloys), which can be precipitation hardened, are designated by the International Alloy Designation System as the 2000 series. Typical uses for wrought Al-Cu alloys include:ASM Handbook. Volume 2, In ''Properties and Selection: Nonferrous alloys and special purpose materials''. ASM, 2002. * 2011: Wire, rod, and bar for screw machine products. Applications where good machinability and good strength are required. *

: 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. * 2017 or Avional (France): Around 1% Si. Good machinability. Acceptable resistance to corrosion in air and mechanical properties. Also called AU4G in France. Used for aircraft applications between the wars in France and Italy. Also saw some use in motor-racing applications from the 1960s, as it is a tolerant alloy that could be press-formed with relatively unsophisticated equipment. * 2024: Aircraft structures, rivets, hardware, truck wheels, screw machine products, and other structural applications. * 2036: Sheet for auto body panels * 2048: Sheet and plate in structural components for aerospace application and military equipment

Aviation

German scientific literature openly published information about duralumin, its composition and heat treatment, before the outbreak of

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

in 1914. Despite this, use of the alloy outside Germany did not occur until after fighting ended in 1918. Reports of German use during World War I, even in technical journals such as ''Flight'', could still mis-identify its key alloying component as magnesium rather than copper. Engineers in the UK showed little interest in duralumin until after the war. The earliest known attempt to use duralumin for a heavier-than-air aircraft structure occurred in 1916, when Hugo Junkers first introduced its use in the airframe of the

Junkers J 3 The Junkers J 3 was an all-metal single-seat experimental fighter aircraft. Design and development A major drawback of the previous J 1 and J 2 designs was the weight of their overall construction, which consisted of heavy iron sheets and pi ...

, a single-engined monoplane "technology demonstrator" that marked the first use of the Junkers trademark duralumin corrugated skinning. The Junkers company completed only the covered wings and tubular fuselage framework of the J 3 before abandoning its development. The slightly later, solely ''IdFlieg''-designated Junkers J.I armoured sesquiplane of 1917, known to the factory as the Junkers J 4, had its all-metal wings and horizontal stabilizer made in the same manner as the J 3's wings had been, like the experimental and airworthy all-duralumin

Junkers J 7 The Junkers D.I (factory designation J 9) was a monoplane fighter aircraft produced in Germany late in World War I, significant for becoming the first all-metal fighter to enter service. The prototype, a private venture by Junkers named the J 7, ...

single-seat fighter design, which led to the

Junkers D.I The Junkers D.I (factory designation J 9) was a monoplane fighter aircraft produced in Germany late in World War I, significant for becoming the first all-metal fighter to enter service. The prototype, a private venture by Junkers named the J 7, ...

low-wing monoplane fighter, introducing all-duralumin aircraft structural technology to German military aviation in 1918. Its first use in aerostatic airframes came in rigid

airship An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early ...

frames, eventually including all those of the "Great Airship" era of the 1920s and 1930s: the British-built R-100, the German passenger Zeppelins LZ 127 ''Graf Zeppelin'', LZ 129 ''Hindenburg'', LZ 130 ''Graf Zeppelin II'', and the U.S. Navy airships USS ''Los Angeles'' (ZR-3, ex-LZ 126), USS ''Akron'' (ZRS-4) and USS ''Macon'' (ZRS-5).

Bicycling

Duralumin was used to manufacture bicycle components and framesets from the 1930s to 1990s. Several companies in Saint-Étienne, France stood out for their early, innovative adoption of duralumin: in 1932, Verot et Perrin developed the first light alloy crank arms; in 1934, Haubtmann released a complete crankset; from 1935 on, Duralumin freewheels, derailleurs, pedals, brakes and handlebars were manufactured by several companies. Complete framesets followed quickly, including those manufactured by: Mercier (and Aviac and other licensees) with their popular Meca Dural family of models, the Pelissier brothers and their race-worthy La Perle models, and Nicolas Barra and his exquisite mid-twentieth century “Barralumin” creations. Other names that come up here also included: Pierre Caminade, with his beautiful Caminargent creations and their exotic octagonal tubing, and also Gnome et Rhône, with its deep heritage as an aircraft engine manufacturer that also diversified into motorcycles, velomotors and bicycles after World War Two. Mitsubishi Heavy Industries, which was prohibited from producing aircraft during the American occupation of Japan, manufactured the “cross” bicycle out of surplus wartime duralumin in 1946. The “cross” was designed by Kiro Honjo, a former aircraft designer responsible for the Mitsubishi G4M. Duralumin use in bicycle manufacturing faded in the 1970s and 1980s.

Vitus (bicycle company) Vitus is a French bicycle manufacturer best known for its steel cycle frame tubing, and its frames built with aluminium tubes joined to aluminium lugs by bonding - a construction method the company pioneered in the late 1970s. Frames Compared to ...

nonetheless released the venerable “979” frameset in 1979, a “Duralinox” model that became an instant classic among cyclists. The Vitus 979 was the first production aluminium frameset whose thin-wall 5083/5086 tubing was slip-fit and then glued together using a dry heat-activated epoxy. The result was an extremely lightweight but very durable frameset. Production of the Vitus 979 continued until 1992.

References

{{Authority control Aluminium alloys Products introduced in 1909 Aerospace materials fr:Alliages d'aluminium pour corroyage#Série 2000 (aluminium cuivre)