What C22000 Commercial Bronze Is
C22000 is the UNS designation for commercial bronze, a wrought copper-zinc alloy that is nominally 90 % copper and 10 % zinc. It is called a bronze by tradition, but chemically it belongs to the brass family because zinc, not tin, is the alloying addition. Under ASTM B36/B36M, which covers brass plate, sheet, strip and rolled bar, the specified ranges are copper 89.0-91.0 %, zinc 9.0-11.0 %, lead 0.05 % maximum and iron 0.05 % maximum. The high copper content gives the alloy its warm reddish-gold colour, which is why a large part of its consumption is architectural and decorative.
| Property | Typical value for C22000 |
|---|---|
| Nominal composition | 90 % Cu / 10 % Zn |
| Electrical conductivity (annealed) | about 28 % IACS |
| Thermal conductivity | about 189 W/m·K |
| Common tempers (ASTM B36/B36M) | O60 soft anneal, H01, H02, H04 |
| Typical product forms | sheet, strip, plate, wire, seamless tube |
Electrical, Electronic and Connector Applications
Although C22000 conducts far less current than ETP copper, its combination of moderate conductivity, excellent ductility and easy soldering and brazing makes it a standard material for stamped and formed contacts. It appears in terminal strips, connector shells, fuse clips, busbar laminations and shielding components where the part must be bent to tight radii without cracking. The alloy takes bright electroplating well, so tin, nickel and silver finishes bond reliably, and it resists atmospheric tarnish better than pure copper in indoor service.
Architectural, Decorative and Hardware Uses
The reddish colour and the ability to hold a brushed, satin or polished finish make C22000 the traditional choice for architectural trim, door and window hardware, escutcheons, handrails, kick plates, grilles and signage. Exposed surfaces develop a gradual, even patina instead of the blotchy staining that lower-copper brasses show. The same surface quality drives its use in costume jewellery, watch components, buttons, zipper parts and cosmetic packaging, where a consistent colour match between production lots is often the critical acceptance criterion.
Industrial, Marine and Process Applications
C22000 resists fresh water, steam and many neutral salt solutions, so it is used for plumbing fittings, flexible hose couplings, valve trim, rivets, screws and grommets. It serves in heat exchanger and condenser components where moderate thermal conductivity is adequate, and in ammunition and ordnance-related components. In marine atmospheres it performs well when exposed to splash and spray but should not be specified for continuously immersed seawater service; the copper-nickel grades such as C70600 and C71500 governed by ASTM B466 and ASTM B122 are the correct materials for that duty.
Forming, Joining and Corrosion Limits
The alloy is among the most formable of the brasses. It can be deep drawn, spun, stamped, blanked and bent to small radii in the soft tempers, and it is readily joined by soft soldering, silver brazing, resistance welding and, with suitable practice, gas and arc welding. The zinc content means the alloy is susceptible to dezincification in aggressive waters and to stress corrosion cracking in ammoniacal environments, so parts that see ammonia or amine-bearing media, or that are cold formed and left highly stressed, should be stress relief annealed and, where pitting is a risk, an inhibitor-treated or alternative alloy selected.
Ordering Checklist for C22000 Product
A complete order states the UNS number, the product form, the temper designation to ASTM B601, the governing specification and the dimensions and tolerances. Where the part is to be plated and formed, add the grain size or bend test requirement, since coarse grain causes orange-peel surfaces after forming. Where colour match matters, request a colour or visual standard with the shipment. For tube, ASTM B135/B135M applies; for wire, ASTM B134/B134M.
Frequently Asked Questions
Q: Is C22000 bronze or brass?
A: Chemically it is a brass, since it is alloyed with zinc rather than tin. The name commercial bronze is a traditional trade term, and the UNS number C22000 is the unambiguous identifier to use on drawings and purchase orders.
Q: What is the electrical conductivity of C22000?
A: Approximately 28 % IACS in the annealed condition, which is well below the 100 % IACS of ETP copper. It is used for contacts and terminals on the basis of formability and corrosion behaviour rather than current-carrying capacity.
Q: Can C22000 be used in seawater?
A: It tolerates splash and spray zones and atmospheric marine exposure, but continuous immersion in seawater promotes dezincification. Copper-nickel alloys such as C70600 or C71500 are the appropriate choice for immersed marine duty.
Q: Which specification covers C22000 sheet and strip?
A: ASTM B36/B36M covers brass plate, sheet, strip and rolled bar, including C22000. Seamless tube is covered by ASTM B135/B135M and wire by ASTM B134/B134M.
Q: How is C22000 softened after cold forming?
A: An anneal in the soft-anneal range followed by controlled cooling restores ductility. The result is ordered as temper O60 under the ASTM B601 temper designation system, and it is the usual condition for severe forming operations.
Q: Does C22000 dealloy in potable water?
A: Dezincification resistance depends on water chemistry, temperature and chloride level. Where potable water is involved, verify the local water analysis and consider a dezincification-resistant grade if the water is aggressive or the pipework runs hot.
