Brass is an alloy of copper and zinc. In manufacture,lump zinc is added to molten copper,and the mixture is poured either into castingsready for use or into billets for further workingby rolling, extruding, forging, or a similar process.Brasses containing 75 to 85% copper arered-gold and malleable; those containing 60 to70% are yellow and also malleable; and thosecontaining 50% or less copper are white, brittle,and not malleable.
Copper–zinc alloys whose zinc contentranges up to 40% with the copper crystal structureface-centered cubic (fcc) are consideredbrass. This solid solution alpha brass has goodmechanical properties, combining strength withductility. Corrosion resistance is very good, butelectrical conductivity is considerably lowerthan for copper.
Beta brass contains nearly equal proportionsof copper and zinc. Specific brasses aredesignated as follows: gilding (95% copper;5% zinc), red (85:15), low (80:20), and admiralty(70:29, with balance of tin). Naval brassis 59 to 62% copper, with about 1% tin, lessthan that of lead and iron, and the remainderzinc. With small amounts of other metals,other names are used. Leaded brass is used forcastings. These alloys have essentially thesame range of zinc content as the straightbrasses. Lead is present, ranging from lessthan 1 to 3.25%, to improve machinability and related operations. Lead also improves antifrictionand bearing properties.
