Gunmetal

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For other uses, see Gunmetal (disambiguation).
Gunmetal parts

Gunmetal, also known as red brass in the United States,[1] is a type of bronze – an alloy of copper (88%), tin (10%), and zinc (2%).[2] Originally used chiefly for making guns, gunmetal was eventually superseded by steel. Gunmetal casts and machines well and is resistant to corrosion from steam and salt water,[3] and is used to make steam and hydraulic castings, valves, and gears, and also statues and various small objects, e.g. buttons. It has a tensile strength of 221 to 310 MPa, a specific gravity of 8.7, a density 8,719 kg/m3, and a Brinell hardness of 65 to 74.

Variants[edit]

  • Gunmetal ingot is a related alloy where the zinc is replaced by 2% lead; this makes the alloy easier to cast, but it has less strength.[4]
  • Modified gunmetal contains lead in addition to the zinc; it is typically composed of 86% copper, 9.5% tin, 2.5% lead, and 2% zinc. It is used for gears and bearings.[4]
  • U.S. Government bronze specification G C90500 is composed of 88% copper, 10% tin, and 2% zinc.
  • G bronze (or Copper Alloy No. C90300) contains 88% copper, 8% tin, and 4% zinc.[4][5]
  • U.S. Government bronze specification H is composed of 83% copper, 14% tin, 3% zinc, and 0.8% phosphorus.[citation needed]
  • Red brass can be considered both a brass and a bronze. It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc. It is used to produce pipes, valves, and plumbing fixtures, and is considered to offer a good mixture of corrosion resistance, strength, and ease of casting.[6] Copper Alloys C23000, which is also known as red brass, contains 84-86% copper, 0.05% each iron and lead, with the balance being zinc.[7]

Gunmetal can also mean steel treated to simulate gunmetal bronze.[2] Bushings made of this metal are used in machinery.

Other uses[edit]

The Victoria Cross, Britain's highest award for military valour, is traditionally known to be made using gunmetal from a cannon captured at the Siege of Sevastopol during the Crimean War. However, recent research has expressed some doubts over this theory, as it shows the source of early Victoria Crosses to be from Chinese cannons.[8]

The British Gwalior Star medal, awarded to the British participants in the 1843 campaign against the Scindias is made of guns captured at the Battles of Maharajpur and Punniar, during the Gwalior Campaign.

Gun money, Irish late 17th century emergency coins, contains gunmetal, as worn and scrapped guns were used to make them, but also many other metals, in particular brass and bronze, as people donated pots and pans and other metal objects.

Color[edit]

A Lamborghini Gallardo sporting gunmetal colored wheels

Gunmetal gray refers to a dark grey color with a bluish and purplish tinge.

References[edit]

  1. ^ "Gunmetal". Retrieved 2008-04-09. 
  2. ^ a b "Gunmetal". Retrieved 2008-04-09. 
  3. ^ "Gunmetal". Retrieved 2008-04-09. 
  4. ^ a b c Brady, George Stuart; Henry R. Clauser; John A. Vaccari (2002). Materials Handbook. McGraw-Hill Professional. pp. 468–469. ISBN 0-07-136076-X. 
  5. ^ "C90300 Bronze Navy G - CDA 903". Anchor Bronze & Metals, Inc. 
  6. ^ Ammen, C.W. (2000). Metalcasting. McGraw-Hill Professional. p. 133. ISBN 0-07-134246-X. 
  7. ^ "C23000 Copper Alloys [Red Brass, C230] Material Property Data Sheet". Metal Suppliers Online. 
  8. ^ Davies, Catronia (28 December 2005). "Author explodes myth of the gunmetal VC". London: The Telegraph. Retrieved 16 June 2007.