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[O. Fr.,=combine], substance with metallic properties that consists of a metal fused with one or more metals or nonmetals. Alloys may be a homogeneous solid solution, a heterogeneous mixture of tiny crystals, a true chemical compound, or a mixture of these.
..... Click the link for more information. 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.
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.
REFERENCESmiriagin, A. P. Promyshlennye tsvetnye metally i splavy, 2nd ed. Moscow, 1956.
I. I. NOVIKOV