Copper Alloys

Copper is used widely in pure state and also in alloys with other material; it is an important engineering material.  It is important in electrical industry in its pure state, and it is high electrical conductivity and corrosion resistance.  In mechanical engineering industry, copper alloys are widely used, alloyed copper in the form of brass and bronze. Copper has the good tensile strength, controllable annealing properties, and soldering and joining characteristics. Copper alloys cannot show the sharply defined yield point, so the yield strength will be reported either 0.5% extension under load, or 0.55 offset. If the material is cold worked or hardened, it will become less ductile, and produce strength that approaches tensile strength. According to temper, the copper is specified and is established by annealing or cold working.

Copper Alloys – Brass, Bronze, Phosphorus Bronze, Becu, Cupro Nickel

A brass is yellow in color and is an alloy of copper with zinc. Brasses can be very sensitive to selective leakage corrosion under certain condition, when zinc is leaked from alloy, by leaving behind a spongy copper structure. In the homes of ancient Rome, brass object can be found dating back to 100 B.C. but not before.

A bronze is an alloy of copper, most often tin, and also aluminium and silicon. Al bronzes are the alloys of copper and aluminium. The Al contentment ranges from 5 % to 11 %. Sometimes iron, nickel, manganese and silicon are added, because they have higher strength and corrosion resistance than bronzes especially in marine environment and have low reactivity to sulfur compounds.

Bronze is copper allowed with tin commonly with 10%. Brass is copper alloyed with Zinc commonly with 30%, so it does not decrease corrosion resistance of copper. Red brass is commonly copper alloyed 15% with Zinc. Cupro nickel may be 69.4% to 96% copper. Standard cupro nickel tin C70260 is 97% copper, 2% tin, 0.5% silicon. In deep drawn and flat stamped components; brass, bronze and phosphorus bronze are used commonly. Commercial bronze “combro” is most commonly 90%, copper 10% zinc alloy and as a connector it has good applications.

Beryllium copper is also called as copper beryllium, and it is most often used in hermetic seals, because the thermal expansion of the alloy is nearly same as the glass used in hermetic seals. The metal will expand and contracts equally as the glass expands and contracts, so the glass does not get cracked. These are copper alloys.

Questions:

• What is copper alloy?
• What is the color of brass?