What Is C22000 Commercial Bronze?
C22000, known as commercial bronze or 90-10 bronze, is a copper-zinc alloy defined by UNS C22000. Its nominal composition is copper 89.0–91.0%, lead 0.05% max, iron 0.05% max, with the balance zinc. Despite the word "bronze" in its common name, the main alloying element is zinc, not tin, so the alloy belongs to the copper-zinc (brass) family rather than the tin bronze family. The designation 90-10 refers to the approximate 90% copper and 10% zinc split, which gives the metal a rich golden color and a balanced set of mechanical and corrosion properties.
Composition and Physical Properties
| Property | Typical Value |
| Copper content | 89.0–91.0% |
| Zinc content | Balance |
| Density | 8.80 g/cm³ |
| Melting range | 1020–1045 °C |
| Electrical conductivity (annealed) | ~43% IACS |
| Thermal conductivity | ~121 W/(m·K) |
| Machinability rating | 40% of free-cutting brass C36000 |
| Tensile strength | ~290 MPa (42 ksi) annealed to ~550 MPa (80 ksi) spring temper |
These values follow the Copper Development Association data for C22000; actual properties vary with temper and product form.
Key Advantages of C22000
Strength and durability: cold working raises tensile strength from about 290 MPa in the annealed condition to roughly 550 MPa in the spring temper, with good fatigue resistance for springs, fasteners, and small mechanical parts. Corrosion resistance: C22000 forms a protective patina in the atmosphere and resists fresh water and mild chemicals; in marine exposure it performs well but, like all copper-zinc alloys, can suffer dezincification in aggressive, chloride-rich waters. Formability: in the annealed temper the alloy is highly ductile and can be stamped, drawn, bent, and rolled into complex shapes, and it is easily joined by brazing and soldering. Wear behavior: a low coefficient of friction makes it useful for bushings, valve stems, and sliding contacts. Aesthetics: the warm golden tone and aging patina suit architectural trim, decorative hardware, and jewelry.
Applications of C22000
C22000 is used for architectural and building hardware such as escutcheons, door trim, railings, and decorative panels; fasteners, rivets, and eyelets; cosmetic cases and jewelry components; marine fittings and small hardware; ammunition cartridge cases and other drawn components; and musical instrument parts. Where moderate electrical conductivity combined with strength is needed, it also appears in terminals and small current-carrying components, although it is not a substitute for high-conductivity copper in power applications.
Limitations and Selection Considerations
C22000 is more costly than zinc-rich brasses because it contains less zinc and more copper, yet it cannot match tin bronzes in bearing load capacity or leaded brasses in machinability. Its conductivity, roughly 43% IACS, is far below pure copper, and heavy cold working reduces ductility, so intermediate annealing may be needed for multi-step forming. In highly corrosive or high-temperature service, tin bronze or other copper alloys may be more appropriate. Engineers should therefore select C22000 when appearance, corrosion resistance, and formability matter more than maximum conductivity, machinability, or extreme-duty bearing performance.
FAQ
Is C22000 a tin bronze?
No. C22000 is a copper-zinc alloy (commercial bronze, 90% copper and 10% zinc) with essentially no tin. Alloys such as C90700 or C90500, which contain 8–10% tin, are true tin bronzes with different properties and different UNS designations.
What is C22000 used for?
Common uses include architectural trim and hardware, rivets, fasteners, eyelets, cosmetic cases, jewelry, marine fittings, and small drawn or stamped components where a golden appearance and good corrosion resistance are desired.
Can C22000 be welded?
C22000 is readily joined by brazing and soldering. Arc welding is possible but difficult because zinc vaporizes during welding, causing porosity and weakening the joint; for welded assemblies, a weldable copper alloy or a different joining method is usually preferred.
Is C22000 corrosion resistant in seawater?
C22000 has good resistance to marine atmospheres and is used in coastal architecture, but in stagnant or heavily chloride-laden seawater it can suffer pitting and dezincification. Copper-nickel alloys or aluminum bronzes are better choices for prolonged immersion in seawater.
What is the electrical conductivity of C22000?
The annealed conductivity is about 43% IACS, roughly two-fifths that of pure copper. This is adequate for terminals and small electrical parts but not for high-current busbars or power cables.
Does C22000 work harden?
Yes. Cold working such as rolling or drawing increases strength and hardness but reduces ductility. If further forming is required after heavy cold work, the part should be annealed to restore formability.
