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Classification and Properties of Copper and Copper Alloys by Austral Wright Metals Sunday, 22 Nov, 2009

Topics Covered
Background
Copper and Copper Alloys
Selection of Copper and Copper Alloys
Properties of Alloys
Different Types of Metal Alloys
Different Types of Metal Alloys Classification of Wrought Copper Alloys
Classification of Cast Copper Alloys

Background
Austral Wright Metals - part of the Crane Group of Companies, is the result of the merger of two long established and well respected Australian owned metal distribution companies. Austral Bronze Crane Copper Ltd and Wright and Company Pty Ltd.
This merger has bought together Australia's leaders in the distribution of:
Aluminium - Coil, sheet, plate, tread plate etc
Copper, brass, bronze - Sheet, coil, extrusions and tube
Nickel and High Performance Alloys - Hollow and bar, sheet, plate in alloys such as Incoloy, Inconel and Monel
Stainless steel - sheet, coil, plate, flat, angle, round, tube, fittings, consumables
High Performance Materials including, titanium, duplex alloys, cobalt alloys, copper nickels, welding consumables and other high technology metals.

Copper and Copper Alloys
Copper and copper alloys are one of the major groups of commercial metals. They offer a wide range of properties, including excellent electrical and thermal conductivity, outstanding corrosion resistance, good strength and fatigue resistance, and appearance. They can be readily worked, brazed and welded.

Selection of Copper and Copper Alloys
The primary selection criteria for copper and copper alloys include:
Electrical conductivity: copper has the highest conductivity of the engineering metals. Silver or other elements may be added to increase strength, softening resistance or other properties without major loss of conductivity.
Thermal conductivity: this property is similar to electrical conductivity. Alloys of copper may be used for this property, where good corrosion resistance compensates for loss of conductivity with increased alloying.
Colour and appearance: many of the copper alloys have a distinctive colour, which may change as the object weathers. For most of alloys it is easy to prepare and maintain the surface to a high standard, even in adverse corrosion conditions. Many of the alloys are used in decorative applications, either in their native form or after metal plating. The alloys have specific colours, ranging from the salmon pink of copper through yellow, gold and green to dark bronze in the weathered condition. Atmospheric exposure can produce a green or bronze surface, and prepatinated alloys are available in some product forms.
Ease of fabrication: most of the alloys can be easily cast, hot or cold formed, machined, joined etc.These alloys are often the standard against which other metals are compared.

Properties of Alloys
Many of the alloys are solid solution strengthened, but are based on the copper crystal structure and have good ductility. Most alloys can be further strengthened by cold work, which improves tensile and fatigue strength while retaining useful ductility. Some alloys can be dispersion strengthened, and a few can be age hardened to very high strength levels.

Different Types of Metal Alloys
1.Copper are essentially commercially pure copper, which ordinarily is very soft and ductile, containing up to about 0.7% total impurities. These materials are used for their electrical and thermal conductivity, corrosion resistance, appearance and colour, and ease of working. They have the highest conductivity of the engineering metals and are very ductile and easy to braze, and generally to weld. Typical applications include electrical wiring and fittings, busbars, heat exchangers, roofs, wall cladding, tubes for water, air and process equipment.
2.High copper alloys contain small amounts of various alloying elements such as beryllium, chromium, zirconium, tin, silver, sulphur or iron. These elements modify one or more of the basic properties of copper, such as strength, creep resistance, machinability or weldability. Most of the uses are similar to those given above for coppers, but the conditions of application are more extreme.
3.Brasses are copper zinc alloys containing up to about 45% zinc, with possibly small additions of lead for machinability, and tin for strength. Copper zinc alloys are single phase up to about 37% zinc in the wrought condition. The single phase alloys have excellent ductility, and are often used in the cold worked condition for better strength. Alloys with more than about 37% zinc are dual phase, and have even higher strength, but limited ductility at room temperature compared to the single phase alloys. The dual phase brasses are usually cast or hot worked. Typical uses for brasses are architecture, drawn & spun containers and components, radiator cores and tanks, electrical terminals, plugs and lamp fittings, locks, door handles, name plates, plumbers hardware, fasteners, cartridge cases, cylinder liners for pumps.
4.Bronzes are alloys of copper with tin, plus at least one of phosphorus, aluminium, silicon, manganese and nickel. These alloys can achieve high strengths, combined with good corrosion resistance. They are used for springs and fixtures, metal forming dies, bearings, bushes, terminals, contacts and connectors, architectural fittings and features. The use of cast bronze for statuary is well known.
5.Copper nickel are alloys of copper with nickel, with a small amount of iron and sometimes other minor alloying additions such as chromium or tin. The alloys have outstanding corrosion resistance in waters, and are used extensively in sea water applications such as heat exchangers, condensers, pumps and piping systems, sheathing for boat hulls.
6.Nickel silvers contain 55 – 65% copper alloyed with nickel and zinc, and sometimes an addition of lead to promote machinability. These alloys get their misleading name from their appearance, which is similar to pure silver, although they contain no addition of silver. They are used for jewellery and name plates and as a base for silver plate (EPNS), as springs, fasteners, coins, keys and camera parts.

Classification of Wrought Copper Alloys
The classification of wrought copper alloys is summarised in the following table.
Table 1. Classification of wrought copper alloys

Class NameUNS NumbersComposition Applications
CoppersC10100 - C1576099% Copper Electrical conductors & connectors, water supply, heat exchangers, tanks, chemical equipment.
High-copper alloysC16200-C19600 96% Copper Electrical conductors & connectors, springs, fasteners.
BrassesC20500 - C28580 Cu - Zn Deep drawn containers, tanks, heat exchangers, architectural panels, coins.
Leaded brassesC31200 - C38590 Cu - Zn - Pb Cylinders, builders hardware, wear plates, fasteners.
Tin brassesC40400 - C49080 Cu - Zn - Sn - (Pb) Electrical switches, springs, terminals, bearings.
Other copper-zinc alloysC66400 - C69900  Valve stems.
Phosphor bronzesC50100 - C52400 Cu - Sn - P Fasteners, springs, chemical hardware, wear plates.
Leaded phosphor bronzesC53200 - C54800 Cu - Sn - Pb - P Bearings, bushings, gears, valves.
Aluminium bronzesC60600 - C64400 Cu - Al - Ni - Fe - Si - Sn Heat exchangers, pump parts, machine parts, structural members.
Silicon bronzesC64700 - C66100 Cu - Si - Sn Fasteners, springs, electrical connectors.
Copper - nickelsC70000 - C79900 Cu - Ni - Fe Condensers, heat exchangers, brake lines, salt water pipes.
Nickel silversC73200 - C79900 Cu - Ni - Zn Sliver plate (EPNS), nameplates, hollow ware

Classification of Cast Copper Alloys
The classification of cast copper alloys is summarised in the following table.
Table 2. Classification of cast copper alloys

Class NameUNS NumbersComposition Applications
CoppersC80100 - C81100 99% Copper Electrical & thermal conductors
High-copper alloysC81300 - C82800 94% Copper High strength electrical conductors, including spot welding electrodes
Red brassesC83300 - C85800 Cu - Zn - Sn - (Pb) (75 - 89% Cu) Valves, pump parts, plumbing hardware
Yellow brassesC85200 - C85800 Cu - Zn - Sn - (Pb) (57 - 74% Cu) Fittings, trim, builders hardware
Manganese bronzesC86100 - C86800 Cu - Zn - Mn - Fe - (Pb) Gears, bearings, bushings, marine fittings
Silicon bronzes, silicon brassesC87300 - C87900 Cu - Zn - Si Gears, bearings, bushings, marine fittings
Tin bronzesC90200 - C94500 Cu - Sn - Zn - (Pb) Gears, bearings, bushings, pump parts
Nickel- tin bronzesC94700 - C94900 Cu - Ni - Sn - Zn - (Pb) Wear parts, low speed bearings
Aluminium bronzesC95200 - C95810 Cu - Al - Fe - Ni Gears, bearings, bushings, pump parts, pickling equipment, non sparking tools
Copper - nickelsC96200 - C96800 Cu - Ni - Fe Valves, pumps etc resistant to seawater
Nickel silversC97300 - C97800 Cu - Ni - Zn - (Pb) - Sn Builders hardware, valves, pumps
Miscellaneous alloysC99300 - C99750 -Various

 

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