McGraw-Hill Science & Technology Encyclopedia.
Usually an alloy of copper and tin. Bronze is used in bearings, bushings, gears, valves, and other fittings both for water and steam.
The properties of bronze depend on its composition and working. Lead, zinc, silver, and other metals are added for special-purpose bronzes.
Tin bronze, including statuary bronze, contains 2–20% tin; bell metal 15–25%; and speculum metal up to 33%.
Gun metal contains 8–10% tin plus 2–4% zinc.
Phosphor bronze is tin bronze hardened and strengthened with traces of phosphorus; it is used for fine tubing, wire springs, and machine parts.
Lead bronze may contain up to 30% lead; it is used for cast parts such as low-pressure valves and fittings.
Manganese bronze with 0.5–5% manganese plus other metals, but often no tin, has high strength.
Aluminum bronze also contains no tin; its mechanical properties are superior to those of tin bronze, but it is difficult to cast.
Silicon bronze, with up to 3% silicon, casts well and can be worked hot or cold by rolling, forging, and similar methods.
Beryllium bronze (also called beryllium copper) has about 2% beryllium and no tin.
The alloy is hard and strong and can be further hardened and strengthened by precipitation hardening; it is one of the few copper alloys that responds to heat treatment, approaching three times the strength of structural steel.
See also Alloy; Copper; Tin.