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Slide 7 of 69
Notes:
Brasses containing a minimum of 63% copper are termed alpha brasses or cold working brasses and are highly ductile at room temperature, and are readily deformed by cold rolling, deep drawing, bending, spinning cold heading, thread rolling etc. The best known of these alloys is 70/30 or cartridge brass so called because it is easily deep drawn and used for making cartridge cases. Alloys with a higher copper content (80%-90%) and which are gold in colour are used extensively for decorative metalwork, costume jewellery, badges and buttons as well as rolled formed architectural applications because of their high level of cold ductility.-
Brasses containing 35%-45% zinc are known as alpha-beta or duplex brasses because they contain a mixture of the original solid solution (alpha phase) and a new solid solution of higher zinc content (beta phase). Their ability to be deformed at room temperature (cold worked) is limited, but they are far more workable at elevated temperatures and are ideal for extruding into complex solid and hollow shapes and hot forging.
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NB Copper alloys containing 5% zinc, tin and lead are known in the USA as “red brass” but in the UK are classified as leaded gunmetal.
