Brass alloy is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure.
Brass is similar to bronze, another alloy containing copper that uses tin instead of zinc.Both bronze and brass also may include small proportions of a range of other elements including arsenic, lead, phosphorus, aluminum, manganese, and silicon. Historically, the distinction between the two alloys has been less consistent and clear,and modern practice in museums and archaeology increasingly avoids both terms for historical objects in favor of the more general "copper alloy".
Brass has long been a popular material for decoration due to its bright, gold-like appearance; being used for drawer pulls and doorknobs. It has also been widely used to make utensils due to properties such as having a low melting point, high workability (both with hand tools and with modern turning and milling machines), durability, and electrical and thermal conductivity.
Brass alloy is still commonly used in applications where corrosion resistance and low friction are required, such as locks, hinges, gears, bearings, ammunition casings, zippers, plumbing, hose couplings, valves, and electrical plugs and sockets. It is used extensively for musical instruments such as horns and bells, and also used as a substitute of copper in making costume jewelry, fashion jewelry, and other imitation jewelry. The composition of brass, generally 66% copper and 34% zinc, makes it a favorable substitute for copper based jewelry, as it exhibits greater resistance to corrosion. Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials.
|Class||Proportion by weight (%)||Notes|
|Alpha brasses||> 65||< 35||Alpha brasses are malleable, can be worked cold, and are used in pressing, forging, or similar applications. They contain only one phase, with face-centered cubic crystal structure. With their high proportion of copper, these brasses have a more golden hue than others. The alpha phase is a substitution solid solution of zinc in copper. It is close in properties to copper, tough, strong, and somewhat difficult to machine. Best formability is with 32% of zinc. Corrosion-resistant red brasses, with 15% of zinc or less, belong here.|
|Alpha-beta brasses||55–65||35–45||Also called duplex brasses, these are suited for hot working. They contain both α and β' phases; the β'-phase is ordered body-centered cubic, with zinc atoms in the center of the cubes, and is harder and stronger than α. Alpha-beta brasses are usually worked hot. The higher proportion of zinc means these brasses are brighter than alpha brasses. At 45% of zinc the alloy has the highest strength.|
|Beta brasses||50–55||45–50||Beta brasses can only be worked hot, and are harder, stronger, and suitable for casting. The high zinc-low copper content means these are some of the brightest and least-golden of the common brasses.|
|Gamma brasses||33–39||61–67||There are also Ag-Zn and Au-Zn gamma brasses, Ag 30–50%, Au 41%.The gamma phase is a cubic-lattice intermetallic compound, Cu5Zn8.|
|White brass||< 50||> 50||These are too brittle for general use. The term may also refer to certain types of nickel silver alloys as well as Cu-Zn-Sn alloys with high proportions (typically 40%+) of tin and/or zinc, as well as predominantly zinc casting alloys with copper additives. These have virtually no yellow coloring at all, and instead have a much more silvery appearance.|
shaft parts with gearing
machining and knurling
parts for valve
CuZn39Pb3 Brass machining
and milling parts
turning rod parts
CuZn40Pb2 Brass nut