Brass
Brass is primarily an alloy of copper and zinc to which additions of other elements such as tin, manganese, arsenic, aluminium, silicon and lead are often made. These additions are usually small (less than 5%) but enhance the individual properties of the alloy, resulting in a material that is ideal for specific application areas. The variety of compositions give specific benefits such as a good strength and ductility or excellent corrosion resistance, high wear resistance, free machinability or high conductivity. With a grade to suit every industrial sector, brass is regarded as one of the best starting points for designers during material selection when long and cost-effective service is required.
There are over 40 standard types of brass, from naval brass to high tensile brass and dezincification resistant brass (DZR brass) to free machining brass. The unique combination of properties available from brass means it is the most commonly used of all the copper-based alloys. Columbia Metals stocks a wide range of brass in round bar, hexagon, tube, sheet and plate, all available for immediate delivery.
The zinc content of brass can vary from 5 - 40% dependent on the individual grade. Brasses with a higher copper content (above ~63%) can be extensively deformed at room temperature and are widely used for the manufacture of complex components by pressing, deep drawing, spinning and other cold forming processes. These grades are generally produced by extrusion, cold rolling and drawing. When the copper content falls below 63% and no other alloying elements are present, the ductility and cold formability reduce, but these alloys can generally be readily hot worked by forging and stamping. These grades are usually manufactured using hot working, either by extrusion or rolling.
Generally, brass has very good resistance to corrosion, especially in normal atmospheric and freshwater conditions. Over time, outdoor exposure can cause a tarnish film to develop on the surface of the brass. This results in the formation of the trademark green patina associated with copper and its alloys. The brass underneath remains unaffected and will not rust away like iron or steel. Seawater and other more challenging atmospheres can also be handled successfully providing the correct alloy composition are selected. Alloying additions such as aluminium, arsenic, tin and nickel will all impart better corrosion resistance, with grades such as dezincification resistant brass and naval brass being particularly successful in designing components that are in contact with fresh water or sea water.
Elements such as aluminium, nickel, iron and manganese can also be added to improve the strength and hardness levels of a brass. Zamalloy and high tensile brasses such as CZ114 and CZ115 are examples that have been developed for enhanced mechanical properties. These types of brass should be selected for more exacting strength and wear applications such as gas valves and fittings, pumps, fasteners and bearings.
All grades of brass are intrinsically easy to machine, but the addition of lead further improves this property. CZ121 / CW614N has a 3% lead addition and is well known as the free-machining brass that sets the standard by which other materials are judged and rated. Brass can also be readily joined via brazing or soldering which, combined with the other, forming attributes, gives machinists lower tool wearer, higher speeds and lower overall fabrication costs.
• GOOD STRENGTH PROPERTIES
• ATTRACTIVE COLOURATION
• HIGH CORROSION RESISTANCE
• READILY MACHINABLE
• EASILY FORMED / FABRICATED
• READILY SOLDERED / BRAZED
• GOOD WEAR RESISTANCE
• HIGH CONDUCTIVITY VALUES