As the material is cold worked or hardened, it becomes less ductile, and yield strength approaches tensile strength. Copper is specified according to temper, which is established by cold working or annealing. Ductility is sacrificed, of course, to gain strength. The ASME Boiler and Pressure Vessel Code should be used for designing critical copper-alloy parts for service at elevated temperatures. Silicon bronzes, aluminum brasses, and copper nickels are widely used for elevated-temperature applications.
All copper alloys resist corrosion by fresh water and steam.
Copper nickels, aluminum brass, and aluminum bronzes provide superior resistance to saltwater corrosion. Copper alloys have high resistance to alkalies and organic acids, but have poor resistance to inorganic acids. One corrosive situation encountered, particularly in the high-zinc alloy, is dezincification. The brass dissolves as an alloy, but the copper constituent redeposits as a porous, spongy metal. Meanwhile, the zinc component is carried away by the atmosphere or deposited on the surface as an insoluble compound.