Brass

Brass

A yellowish alloy of copper and zinc, sometimes including small amounts of other metals, but usually 67 percent copper and 33 percent zinc. (American Heritage Dictionary). The other materials added to the brass to give special qualities. The copper-zinc proportion may vary from 95% copper and 5% zinc to 55% copper and 45% zinc. Brass varies in color from lemon yellow to deep golden brown according to the amount of zinc: 10%zinc for bronze color; 15% zinc for golden; 20-38% zinc for yellow; and above 45% zinc for silvery white.

Brass is stronger and harder than copper, but not as strong or hard as steel. It is easy to form into various shapes, a good conductor of heat, and generally resistant to corrosion from salt water. Because of these properties, brass is used to make pipes and tubes, weather-stripping and other architectural trim pieces, screws, radiators, musical instruments, and cartridge casings for firearms.

Classification

Alpha brasses are ductile and can be both cold-worked without annealing and hot-worked. Corrosion resistence and electrical and thermal conductivity are fair, these properties decreasing with a decrease in copper content. Alpha brasses have a wide range of color. Copper-base alloys containing more than 64% copper are known as alpha brasses.

Alpha-Beta brasses are copper-base alloys containing from 64% down to 55% copper, and containing between 36% and 45% zinc. They have comparatively high tensile strength and hardness, fairly low melting points, and relative poor corrosion resistance and electrical conductivity. They can be easily hot worked and within limits can be cold work without annealing. Their color range is important because as the copper content decreases, they become less red and at 55% copper the color practically matches that of commercial bronze ; therefore complicated shapes may be made by hot extrusion and used with sheets of commercial bronze.

Leaded brasses are those to which lead is added to increase machinability. They maybe either Alpha or Alpha-Beta brasses and are especially suited for free-machining purposes. They can be easily hot-worked (however, the metal must be supported mechanically) and cold-worked within limits, but they are not as strong, corrosion resistant, or hard as the Alpha and Beta brasses.

Tin brasses also called naval brasses, are used for chemical, steam power plant, and marine equipment.

Manganese-tin alloy is used as substitute for nickel silver, and manganese brass (bronze) is used where high strength and resistance to seawater are required.

Type and use

In the construction field, brasses are used for doors, windows, door and window frames, and ornamental metalwork such as railings, trim and grilles. The brasses are used for finish hardware, plating of hardware, and other miscellaneous accessories such as screws, nut and bolts, anchors, weatherstripping, and ties.

The bulk of brass produced is use in plumbing, heating, and air conditioning and in industrial machinery and equipment, where the special properties of brasses are required.