ALUMINUM BRONZE
A series of wrought and cast copper-aluminum alloys, most of which also contain several other elements, principally iron. Aluminum content ranges from 4 to 15%, depending on the alloy, and iron, if present, from less than 1 to 6%. Alloy designations for wrought aluminum bronzes are C60XXX, C61XXX, C62XXX, C63XXX, and C64XXX; cast alloys are C95XXX. The alloys are also referred to by their nominal aluminum content, such as 5% aluminum bronze, or by other distinguishing alloying ingredients, such as nickel aluminum bronze. Aluminum bronzes are noted for their moderate to high strength, and corrosion resistance in potable, brackish, and sea waters, industrial and marine atmospheres, and various chemicals. They are attacked, however, by oxidizing acids. Because of their pale gold look and amenability to lustrous finishing, some of the alloys are also used for their decorative appeal. Aluminum bronzes are available in a full range of wrought products, and the cast alloys are amenable to various casting methods. Typical applications include condenser and heat-exchanger tubing and tube sheets, fasteners, shafts, cams, gears, bearings, bushings, valves and valve seats, deep-drawn parts, wear plates, pickling equipment, impellers and agitators, nonsparking hardware, and decorative ware. Single-phase (alpha) alloys containing only copper and aluminum can only be strengthened by strain hardening during cold working. The 4 to 7% aluminum bronze C60600 alloy in the form of 0.5-in (13-mm) plate has a tensile yield strength of 17,000 lb/in2 (115 MPa) annealed and 24,000 lb/in2 (165 MPa) in the H04, or “hard,” cold-worked temper. In these same conditions, 1-in (25-mm) diameter rod of aluminum (6 to 8.5%) bronze C61000 has a tensile yield strength of 30,000 lb/in2 (205 MPa) and 55,000 lb/in2 (380 MPa), respectively. Two-phase aluminum bronzes, such as those alloyed with iron or iron and nickel, are typically strengthened by quenching and then are tempered. One such casting alloy, aluminum bronze C95500 (nominally 81% copper, 11 aluminum, 4 iron, 4 nickel), has a tensile yield strength of 60,000 lb/in2 (415 MPa) in the quenched and tempered (TQ50) condition, 50% greater than as cast. Cunial, developed by the Dutch firm Lips B.V. for casting large ship and submarine propellers, is also used for casting molds to form various plastics because of its good thermal conductivity, machinability, polishability, chemical and erosion resistance, nongalling quality, and adequate strength and hardness. The composition is 78.5% minimum copper, 8.5 to 10 aluminum, 4 to 6 nickel, 3.5 to 5.5 iron, 0.5 to 2.5 manganese, and at the most 1 zinc, 0.1 silicon, 0.1 tin and 0.03 lead. The hardness is 180 Brinell and the tensile properties are 94,250 lb/in2 (650 MPa) ultimate strength, 35,525 lb/in2 (245 MPa) yield strength, and 20% elongation.

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