What Is Brass
Brass is a yellow alloy of copper and zinc (67% copper and 33% zinc). Another dictionary meaning says Brass is decorative object made of such an alloy i.e. copper and zinc. The proportions of zinc and copper can be varied to create a range of brasses with varying properties.
Brass has a muted yellow color, somewhat similar to gold. It was known to humans since prehistoric times, even before zinc itself was discovered.
Brass is used in all type of industries, like aerospace, fastening, pneumatic, plumbing sanitary pipe fitting, cable accessories, electrical components,decorative items, construction hardware and machine parts.
Brass also has excellent thermal conductivity making it a first choice for heat exchangers (radiators).
Mainly two types RED and YELLOW: Red brass is 85% copper and 15% zinc, while yellow brass is 60% copper and 40% zinc.
Brass has higher malleability than bronze or zinc. To enhance the machinability of brass, lead is often added in concentrations of around 2%. Aluminium is sometimes also added to brass.
Brass is susceptible to stress corrosion cracking, especially from ammonia or substances containing or releasing ammonia. The problem is sometimes known as season cracking after it was first discovered in brass cartridge cases used for rifle ammunition during the 1920s in the Indian Army. The problem was caused by high residual stresses from cold forming of the cases during manufacture, together with chemical attack from traces of ammonia in the atmosphere.
There are numerous brass types depending on their composition i.e. percentage of copper and zinc, some of them are as follows:-
Admiralty brass contains 30% zinc and 1% tin which inhibits dezincification in most environments.
Alpha brasses (Prince’s metal), with less than 35% zinc, 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.
Alpha-beta brass (Muntz metal), also called duplex brass, is 35-45% zinc and is suited for hot working. It contains both α and β’ phase; the β’-phase is body-centered cubic and is harder and stronger than α. Alpha-beta brasses are usually worked hot.
Aluminium brass contains aluminium, which improves its corrosion resistance. Used in Euro coins (Nordic gold).
Beta brasses, with 45-50% zinc content, can only be worked hot, and are harder, stronger, and suitable for casting.
High brass, contains 65% copper and 35% zinc, has a high tensile strength and is used for springs, screws, rivets.
Low brass is a copper-zinc alloy containing 20% zinc with a light golden color, excellent ductility and is used for flexible metal hoses and metal bellows.
Naval brass, similar to admiralty brass, is a 40% zinc brass and 1% tin.
Red brass, while not technically brass, is an American term for CuZnSn alloy known as gunmetal.
Rich low brass contains 85% copper 15% zinc often used in jewellery applications .
White brass contains more than 50% zinc and is too brittle for general use.
Yellow brass is an American term for 33% zinc brass.