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Copper Alloys - Brasses

Chemical Formula

Cu/Zn Alloys

Topics Covered

Background

Key Properties

Applications

High Pressure Gas Valves

Plumbing Systems

Marine Applications

Gilding Metals

Other Applications

Background

Brasses are alloys of copper and zinc (generally 5 to 40%), and may contain small amounts of other alloying elements. Most are available in a range of forms and can be fabricated by casting, forging, stamping, rolling, extrusion and machining.

They fall into two classes, the alpha alloys with less than 37% zinc which are ductile and can be cold worked and the alpha/beta or duplex alloys which are harder and stronger with limited cold ductility.

Lead can be added as an alloying element resulting in a brass that can be rapidly machined and produces minimal tool wear. Additions of aluminium, iron and manganese to brass improve strength, whilst silicon additions improve wear resistance.

Key Properties

        High ductility (alpha alloys)

        Can be hot worked

        Hardness and brittleness increase with increasing beta alloy formation (i.e as zinc content increases above 37% zinc)

        Aesthetically pleasing colour

Applications

High Pressure Gas Valves

High pressure gas valves are commonly made from high tensile brass containing small additions of aluminium, iron or manganese.

Plumbing Systems

Dezincification resistant brass is used for fittings in valves, connectors and taps in pump and plumbing systems. This particular alloy contains a small addition of arsenic and is specially heat treated so that the composition is homogeneous as water in some countries will attack zinc rich areas of the metal.

Marine Applications

Additions of tin or aluminium to either alpha or duplex brasses improves corrosion resistance in sea and brackish waters for applications such as propellers.

Gilding Metals

Brass containing 10 to 20% zinc has a very similar colour to gold. Hence, this composition is often used for costume jewellery and architectural applications.

Other Applications

Heat exchangers, springs, car radiators, fasteners, hot formed parts, extruded sections, forgings, condenser tubes, architectural, sections, pressure tubing, bearings, bushes, ornamental features, gearwheels.

Primary Author: Dr. Agnes Segal

Source: Materials Information Service, “Using copper and copper alloys” edited by Justin Furness.

For more information on this source please visit The Institute of Materials

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