Brass (alloy)
Brass is a versatile copper-based alloy primarily composed of copper and zinc, with possible additions of other metals like lead, tin, nickel, aluminum, iron, manganese, arsenic, antimony, and phosphorus. This alloy dates back to ancient times, with evidence suggesting that the first brass was unintentionally created by melting copper ore containing zinc. Historically, brass was extensively produced in Western Europe during the eleventh century, leading to the manufacture of various items such as coins and decorative objects.
The composition of brass affects its color and properties; for example, yellow brass, containing about 70% copper, exhibits a golden-yellow hue, while red brass, with over 80% copper, has a reddish color. The addition of zinc enhances the strength and toughness of brass, with optimal ductility achieved at around 30% zinc. Common applications of brass include components for automobiles, plumbing fixtures, and decorative elements, due to its favorable mechanical properties and corrosion resistance.
Brass is often confused with bronze, which is another alloy primarily consisting of copper and tin, used for artistic items like statues and bells. The manufacturing process of brass involves melting copper and mixing it with zinc, followed by rolling and forming into various shapes for diverse uses.
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Brass (alloy)
Brass, a metal alloy, has numerous practical applications because of its ease of fabrication, corrosion resistance, and attractive appearance. It is used in hardware items, electrical fixtures, inexpensive jewelry, and metal decorations.
Definition
Brass is a copper-based alloy consisting mainly of copper and zinc. It can also be mixed with lead, tin, nickel, aluminum, iron, manganese, arsenic, antimony, and phosphorus.
Overview
The first brass was probably made accidentally by melting copper ore that contained a small amount of zinc. The earliest known brass object was made by the Romans about 20 b.c.e. By the eleventh century, brass was made on a large scale throughout Western Europe, and brass coins, kettles, and ornaments were manufactured. In the United States, the brass industry developed mainly in Connecticut; at first it was devoted primarily to making buttons.
The color and composition of brass vary with the amount of copper, which ranges from 55 percent to 95 percent. When the alloy contains about 70 percent copper, it has a golden-yellow color (such brass is called yellow brass or cartridge brass). When it contains 80 percent or more copper, it has a reddish copper color (red brass). When zinc is added, brass becomes stronger and tougher. The ductility (ability to be stretched) improves with increasing amounts of zinc up to about 30 percent. The best combination of strength and ductility occurs in yellow brass.
Lead is added to improve machinability (ease of cutting). Tin and nickel are often added to increase the alloy’s resistance to corrosion and wear. Nickel may be added to obtain a silvery-white color that makes the alloy a more suitable base for silver plating. Aluminum is useful in improving the corrosion resistance of brass in turbulent or fast-moving water. The strength of brass is also improved with the addition of iron, manganese, nickel, and aluminum.
The first step in making brass is to melt copper in an electric furnace. Solid pieces of zinc are then added to the melted copper, and the zinc melts rapidly. After the copper and zinc have been melted and thoroughly mixed, the brass is ready for pouring. It is typically made into blocklike forms (ingots) or small bars (billets), making it easy to work with the brass or to store it. When it is time to make a particular piece, the bars are placed in a furnace, and after they have been reheated to the proper temperature for working, the brass can be rolled and formed into the desired shape. A milling machine removes surface imperfections, and the brass is then cold rolled.
Brass is used in making automobile components, ship propellers, refrigeration and air-conditioning equipment (condenser tubes), decorative elements (architectural trim), plumbing hardware, camera parts, valves, screws, buttons, keys, watch and clock parts, and coins. Some brasses, mainly containing tin and manganese, are called bronzes, which are used to make statues, bells, vases, cups, and a variety of ornaments.