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Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper (88%), tin (10%), and zinc (2%). Originally used chiefly for making guns, gunmetal was eventually superseded by steel. Gunmetal casts and machines well, is resistant to corrosion from steam and salt water, 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== * 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. *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.〔 *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.〔 *U.S. Government bronze specification H is composed of 83% copper, 14% tin, 3% zinc, and 0.8% phosphorus. *Red brass used to produce pipes, valves, and plumbing fixtures, and is considered to offer a good mixture of corrosion resistance, strength, and ease of casting. It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc. * ''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. Gunmetal can also mean steel treated to simulate gunmetal bronze.〔 Bushings made of this metal are used in machinery. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gunmetal」の詳細全文を読む スポンサード リンク
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