Brass

brass, alloy having copper (55%–90%) and zinc (10%–45%) as its essential components. The properties of brass vary with the proportion of copper and zinc and with the addition of small amounts of other elements, such as aluminum, lead, tin, or nickel. In general brass can be forged or hammered into various shapes, rolled into thin sheets, drawn into wires, and machined and cast. Its ductility reaches a maximum with about 30% zinc and its tensile strength with 45%—although this property varies greatly with the mechanical and heat treatment of the alloy. Cartridge brass (70% copper, 30% zinc) is used for cartridge cases, plumbing and lighting fixtures, rivets, screws, and springs. Aluminum brass (not exceeding 3% aluminum) has greater resistance to corrosion than ordinary brass. Brass containing tin (not exceeding 2%) is less liable to corrosion in seawater; it is sometimes called naval brass and is used in naval construction. Dutch metal (80%–85% copper, 15%–20% zinc) is used as a substitute for gold leaf. When iron is added to brass it produces hard, tough alloys. One of these is delta metal (55% copper, 41% zinc, 1%–3% iron, and fractional percentages of tin and manganese), which can be forged, rolled, or cast and is used for bearings, valves, and ship propellers.

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brass

Alloy of copper and zinc, important for its hardness and workability. Brass was first used c. 1200 BC in the Near East, then extensively in China after 220 BC, and soon thereafter by the Romans. In ancient documents, including the Bible, the term brass is often used to denote bronze (copper/tin alloy). The malleability of brass depends on its zinc content; brasses with more than 45% zinc are not workable. Alpha brasses contain less than 40% zinc; beta brasses (40–45% zinc) are less ductile than alpha brasses but stronger. A third group includes brasses with additional elements. Among these are lead brasses, which are more easily machined; naval and admiralty brasses, in which a small amount of tin improves resistance to corrosion by seawater; and aluminum brasses, which provide strength and corrosion resistance where the naval brasses may fail.

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brass

1. an alloy of copper and zinc containing more than 50 per cent of copper. Alpha brass (containing less than 35 per cent of zinc) is used for most engineering materials requiring forging, pressing, etc. Alpha-beta brass (35--45 per cent zinc) is used for hot working and extrusion. Beta brass (45--50 per cent zinc) is used for castings. Small amounts of other metals, such as lead or tin, may be added

2. 

a. the large family of wind instruments including the trumpet, trombone, French horn, etc., each consisting of a brass tube blown directly by means of a cup- or funnel-shaped mouthpiece

b. instruments of this family forming a section in an orchestra

3. a renewable sleeve or bored semicylindrical shell made of brass or bronze, used as a liner for a bearing

4. Brit an engraved brass memorial tablet or plaque, set in the wall or floor of a church

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brass [bras]

(geology)

A British term for sulfides of iron (pyrites) in coal. Also known as brasses.

(metallurgy)

A copper-zinc alloy of varying proportions but typically containing 67% copper and 33% zinc.

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brass

1. Any copper alloy having zinc as the principal alloying element, but often with small quantities of other elements.

2. A plate of brass with memorial inscription and sometimes an effigy engraved on it, set into a church floor to mark a tomb.

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Brass 

a copper-based alloy in which the main additive is zinc (up to 50 percent). Brass was smelted even before the Common Era; until the late 18th century it was produced by fusion of copper with zinc ore mixed with charcoal. Only in the 19th century was this method generally replaced by direct fusion of copper with zinc.

Because of its good hot and cold pressure workability, excellent mechanical properties, attractive color, and relatively low cost, brass is the most common copper alloy. It is produced in the form of sheets, ribbons, rods, tubes, and wire (deformable brass), as well as ingots (cast brass). As the zinc content increases, the color of brass changes from reddish to light yellow. In Russia, brass was called yellow copper rather than red copper.

Simple brasses are alloys of copper only with zinc. Brasses containing up to 10 percent zinc are called tombacs; those containing 10–20 percent zinc are called half-tombacs (low brasses). These alloys, which are characterized by high corrosion resistance and plasticity, are used for making radiator and condenser pipes, as well as sheets and bands for cladding steel. Brass containing about 30 percent zinc and suitable for extensive drawing is called cartridge brass and is widely used for making parts by cold stamping, as well as by molding and drawing.

Aluminum, tin, iron, manganese, nickel, silicon, and lead (up to a total content of about 10 percent) are added to double alloys of copper with zinc to improve their mechanical, anticorrosion, and other characteristics. Multicomponent (or special) brasses are called aluminum, silicon, aluminonickel, and ferroman-ganese brasses. Brass containing about 15 percent zinc and 0.5 percent aluminum has an attractive gold color and is highly resistant to atmospheric corrosion. It is used as a substitute for gold in decorations and objets d’art. Brass with up to 1.5 percent tin added (called naval brass) has improved resistance to corrosion in seawater. The addition of lead (up to 3 percent) makes brass chips brittle and makes possible the production of very smooth surfaces by cutting. Lead brasses are used in the manufacture of motor vehicles and in clock and watch production (clock brasses).

Many brasses containing more than 20–30 percent zinc are susceptible to corrosion cracking caused by the simultaneous action of residual stresses in articles and the corrosive effect of ammonia and sulfur dioxide (in a moist atmosphere). This effect is called the seasonal sickness of brass, since increased corrosion cracking occurs in months with increased moisture in the air. Such cracking is reduced by annealing at 250°-300°C to reduce the residual stresses.

Brass is also used in general mechanical engineering, instrument-making, and heat engineering.

REFERENCE

Smiriagin, A. P. Promyshlennye tsvetnye metally i splavy, 2nd ed. Moscow, 1956.

I. I. NOVIKOV