Copper Alloys — Family Index

1. At a glance

Copper alloys are catalogued under the UNS (Unified Numbering System) with a letter prefix C followed by five digits. The first digit segregates the families:

• Wrought: UNS C1xxxx through C7xxxx.
• Cast: UNS C8xxxx through C9xxxx.

Pure copper sets the conductivity reference: IACS = 100 % corresponds to a resistivity of 1.7241 × 10⁻⁸ Ω·m at 20 °C, equivalent to roughly 58 MS/m (or thermal conductivity ≈ 401 W/(m·K) for OFE/ETP). All copper-alloy conductivities are stated as a % IACS so a 30 % IACS phosphor-bronze conducts about 17 MS/m.

Density of nearly all copper alloys sits in the band 8.3–8.94 g/cm³, modulus 110–125 GPa, melting range 870–1085 °C depending on alloy content. Copper is FCC, so all common alloys are tough and formable down to cryogenic temperatures without a ductile-to-brittle transition.

The seven structural families used through the rest of this note:

Family	UNS range	Principal addition
Pure copper	C10xxx–C15xxx	none / O, P, Ag traces
High-copper alloys	C16xxx–C19xxx	<5 % alloy (Be, Cr, Zr, Ni, Si, Cd)
Brasses	C20xxx–C49xxx	Zn (+Pb, Sn, As, Sb)
Phosphor- and tin-bronzes	C50xxx–C54xxx	Sn + P
Cu-Al, Cu-Si, “miscellaneous” bronzes	C60xxx–C69xxx	Al, Si, Mn
Copper-nickel	C70xxx–C73xxx	Ni (10 %, 30 %)
Nickel-silvers	C74xxx–C79xxx	Ni + Zn

2. UNS designation and equivalents

• UNS C-number: US/CDA designation, 5 digits after the C. First digit identifies the family.
• EN (European): CW prefix + 3 digits + letter for wrought, CC + 3 digits + letter for cast (e.g. ETP copper = CW004A). The trailing letter encodes the chemistry sub-group (A,B,…) rather than temper.
• JIS (Japan): C1xxx–C7xxx, similar numbering rationale to UNS but only 4 digits.
• ASTM B-spec: product-form standards (B36 sheet, B98 silicon-bronze rod, B370 ETP roofing copper, etc.) reference UNS internally.
• Temper codes (ASTM B601): O60 annealed, H01/02/04 quarter/half/full hard cold-rolled, TB00 solution-treated, TF00 age-hardened, TH04 cold-worked + aged.

3. Pure copper

The first family covers commercially pure copper grades, distinguished by how oxygen and residual P are controlled:

• C10100 — OFE (oxygen-free electronic). 99.99 % Cu, < 5 ppm O. Used for klystrons, accelerator cavities, semiconductor lead-frames, cryogenic busbars. ~101 % IACS in the annealed condition (slightly above pure-Cu reference because residuals are eliminated).
• C10200 — OFHC (oxygen-free, high-conductivity). 99.95 % Cu, < 10 ppm O. UHV chambers, RF waveguide.
• C11000 — ETP (electrolytic tough-pitch). 99.90 % Cu with 200–400 ppm O present as Cu₂O. The everyday copper of wire, busbar, roofing, and architectural sheet. ~100 % IACS. Hydrogen embrittlement risk above ~370 °C — Cu₂O reacts with H₂ to form internal steam pockets, so ETP cannot be brazed/welded in reducing atmospheres.
• C12200 — DHP (phosphorus-deoxidized, high-residual P). ~0.02 % P removes the oxide and prevents H-embrittlement, at the cost of conductivity (≈ 85 % IACS). The standard alloy for plumbing and ACR (air-conditioning/refrigeration) tubing, also for solder-joinable architectural copper. ASTM B88 (plumbing), B280 (ACR).
• C12500 — FRTP (fire-refined tough-pitch): lower purity grade for non-electrical uses.
• C14500 — tellurium-copper, C14700 — sulfur-copper: free-machining grades that keep ~90 % IACS — used for screw-machine electrical contacts.

4. High-copper alloys (C16xxx–C19xxx)

Adds < 5 % alloying to give precipitation- or solid-solution-strengthening while preserving most of the conductivity:

• C15000 — Zr-Cu (0.15 % Zr). Retains > 90 % IACS after heavy cold work; resistance-weld electrodes for stainless and Inconel.
• C17200 — beryllium-copper (1.8–2.0 % Be, 0.2 % Co/Ni). The classic age-hardenable copper — solution-treat at 800 °C, quench, age at 315 °C/3 h to obtain UTS ≈ 1380 MPa, 0.2 % yield ≈ 1100 MPa, hardness 40 HRC, ~22 % IACS. Used for spring contacts (connector beams, RF springs), non-sparking hand tools for petrochem/munitions, undersea cable bellows, oil-field down-hole tools. Be exposure is regulated (OSHA PEL 0.2 µg/m³) so dust control is mandatory during machining.
• C17500 (0.6 % Be, 2.5 % Co) and C17510 (0.4 % Be, 2 % Ni): lower-Be, higher-conductivity (45–60 % IACS) variants for resistance-weld tips and high-current switch contacts.
• C18150 — Cr-Zr-Cu (0.8 % Cr, 0.1 % Zr) and C18200 — chromium-copper (0.8 % Cr): age to ~ 450 MPa, 80 % IACS, soften only above 500 °C — the dominant alloys for resistance-spot-welding electrodes and rocket-engine combustion-chamber liners (e.g. SpaceX Merlin/Raptor injectors use a Cu-Cr-Zr or NARloy variant).
• C18700 — leaded-copper (1 % Pb): screw-machine electrical parts where chip-breaking is needed.
• C19400 — Fe-P bearing copper (2.4 % Fe, 0.03 % P, 0.12 % Zn): high-strength lead-frame stamping for IC packages.

5. Brasses — Cu-Zn (C2xxxx–C4xxxx)

α-brasses (< 37 % Zn) are single-phase FCC and very ductile. α+β brasses (37–45 % Zn) trade ductility for strength and machinability. Above ~45 % Zn the alloys are brittle and not used industrially.

• C21000 — gilding metal 95Cu-5Zn: jewelry, coinage cladding, bullet jacket softening.
• C22000 — commercial bronze 90-10: decorative hardware, kick-plates. Despite the “bronze” name it is a brass.
• C23000 — red brass 85-15: plumbing nipples, hose couplings.
• C24000 — low brass 80-20: flexible hose, bellows.
• C26000 — cartridge brass 70-30: most ductile of the brasses (elongation > 60 % annealed). Used for deep-drawn shells (its name), lamp bases, automotive radiator cores, formed-tube applications.
• C26800 / C27000 — yellow brass 65-35: good cold-formability and lower cost than cartridge.
• C28000 — Muntz metal 60-40: α+β, hot-rolled and pressed sections, condenser tube sheets, architectural sheet.
• C36000 — free-cutting brass 61.5Cu-3Pb-35Zn: the machining workhorse of the brasses. Lead provides chip-breaking; machinability rating = 100 (the reference against which all other alloys are scored). Plumbing fittings, valve bodies, hardware. Now being phased out for potable-water use under NSF/ANSI 61 and EU lead restrictions — see §11.
• C37700 — forging brass 60-2Pb-38Zn: Pb improves hot-forgeability; gas valves, plumbing brass.
• C44200/C44300/C44400 — admiralty brass 70-29Zn-1Sn + As/Sb/P inhibitor: the Sn shifts the corrosion potential and the As (or Sb, P) inhibits dezincification — condenser/heat-exchanger tubing for fresh and brackish water.
• C46400 — naval brass 60-39Zn-0.75Sn: the Muntz-metal sibling with Sn for marine resistance — propeller shafts, valve stems, marine hardware.
• C68700 — aluminum-brass 76Cu-22Zn-2Al-As: desalination plant tubing; the Al forms a protective alumina film.

6. Bronzes — Cu-Sn (C5xxxx wrought, C9xxxx cast)

Phosphor-bronzes use P as a deoxidiser and a strengthener; tin gives wear resistance and resilience.

Wrought:

• C51000 — phosphor-bronze A (5 % Sn, 0.2 % P): the dominant spring bronze — Belleville washers, electrical-contact springs, instrument diaphragms. UTS 380 MPa annealed, > 700 MPa hard temper, ~ 15 % IACS.
• C51900, C52100 — 6 % and 8 % Sn: higher-strength springs.
• C52400 — phosphor-bronze D (10 % Sn, 0.2 % P): heavy-duty bushings, gears, lock-washers.
• C54400 — free-cutting phosphor-bronze (4 % Sn, 4 % Pb, 4 % Zn): screw-machine bushings, bearings, pinions.

Cast Cu-Sn bronzes (the gun-metals and bearing bronzes):

• C90300 — gun-metal 88-8-4 (Cu-Sn-Zn): the historic “Admiralty gun-metal” — valve bodies, marine pump housings, statuary.
• C90500 — tin-bronze 88-10-2: higher Sn for better wear.
• C90700 — 89-11 tin-bronze: worm-gear stock.
• C93200 — bearing bronze SAE 660 (83-7-7-3 Cu-Sn-Pb-Zn): the standard sleeve-bearing alloy of North-American industry — pump bushings, electric-motor end-bell bearings, sliding-load bearings. Easy to cast, easy to machine, conforms slightly under load.
• C93700 — high-leaded tin-bronze SAE 64 (80-10-10): slipper bearings, rod ends, dirty/marginal lubrication.
• C93800, C94300 — even higher Pb for emergency-lube applications.

7. Aluminum-bronzes — Cu-Al (C60xxx–C64xxx)

5–12 % Al replaces Sn; gives a tough, work-hardenable alloy with a self-healing Al₂O₃ surface film. Iron and nickel additions strengthen via Cu-Fe-Al intermetallics.

• C61300 (7 % Al, 2.5 % Fe, 0.3 % Sn): condenser/seawater service.
• C61400 (7 % Al, 2.5 % Fe): structural plate, marine.
• C62500 (13 % Al, 4 % Fe): wear-resistant forgings, dies.
• C63000 — nickel-aluminum-bronze “NAB” (10 % Al, 5 % Ni, 3 % Fe): the flagship marine bronze — UTS 750 MPa, yield 470 MPa, excellent seawater corrosion and cavitation resistance. Used for ship propellers (most large commercial and military ship-screws), pump impellers, valve trim, oil-platform fasteners. Mn-NAB variants (with Mn replacing some Fe) are used in nuclear-submarine propellers because their damping reduces tonal noise. Heat-treat-sensitive: a slow cool through 800–500 °C precipitates κ-phases that drop seawater corrosion resistance — post-weld temper at 675 °C is mandated by NAVSEA spec.
• C63200 (9 % Al, 4 % Ni, 3 % Fe): higher-Al sibling of C63000 for valve bodies.
• C64200 (7 % Al, 1.8 % Si): age-hardenable Al-Si-bronze for high-strength fasteners.

8. Silicon-bronzes — Cu-Si (C65xxx)

3 % Si gives a deoxidised, weldable bronze with strength similar to mild steel and outstanding corrosion resistance.

• C65500 — silicon-bronze A “Everdur” (96Cu-3Si-1Mn): the dominant Si-bronze. Readily TIG/MIG-welded without filler-rod issues. Used for marine fasteners (often the only acceptable bolt for wooden boats), hydraulic pressure lines, brewing/distillation tankage, chemical-plant piping. UTS 380 MPa annealed, > 700 MPa hard.
• C65100 — silicon-bronze B (1.5 % Si): softer/cheaper variant for non-structural plumbing.
• C66100 — leaded silicon-bronze: machined valve bodies needing weldability and chip control.

9. Copper-nickel and nickel-silver (C70xxx–C79xxx)

The single most corrosion-resistant copper family — Ni gives complete solid solubility across the binary diagram, no second phase, and a protective Cu-Ni-O film in seawater.

Copper-nickels:

• C70600 — 90Cu-10Ni-1.4Fe-0.8Mn: the workhorse seawater alloy — condenser tubing on naval vessels, offshore fire-water mains, desal plants. Resists biofouling because slowly dissolving Cu²⁺ is toxic to barnacle and mussel settlement. Maximum service ≈ 4.5 m/s seawater velocity before impingement.
• C71500 — 70Cu-30Ni-0.7Fe: highest corrosion resistance of the wrought copper alloys. Used for high-pressure feed-water heaters in nuclear plants, Royal Navy seawater piping (historical CuNi standard), large heat exchangers. Velocity rating ≈ 6 m/s.
• C71640 — 66Cu-30Ni-2Fe-2Mn: sand- and silt-laden seawater — even higher impingement resistance than C71500.
• C72200 — Cu-16Ni-Cr: high-temperature heat-exchanger tubing.
• C72500, C72700, C72900 — Cu-Ni-Sn spinodal alloys (Toughmet / Brush 60 / Brush 70): age via spinodal decomposition rather than precipitation; Be-free substitute for C17200 at comparable strength (UTS ~ 950 MPa), important in oil-and-gas down-hole tools where Be is restricted.

Nickel-silvers (white but contain no silver — the “silver” refers to colour):

• C74500 — 65-10-25 Cu-Ni-Zn: electrical springs.
• C75200 — 65-18-17 Cu-Ni-Zn: instrument cases, hollow-ware, white-looking flatware (“German silver”), optical-frame components. Ni gives the silver-white appearance.
• C77000 — 55-18-27: ornamental sheet, name-plates.
• C79200 — leaded nickel-silver: machined contact-spring carriers.

10. Specialty and high-performance grades

• Glidcop AL-15/-25/-60 — Al₂O₃-dispersion-strengthened copper: internally oxidised Cu-Al consolidates 0.15–0.6 % alumina particles that never coarsen at brazing temperatures. UTS ~ 480 MPa retained after 1 h at 925 °C; ~ 87 % IACS. Used for resistance-weld electrodes (orders-of-magnitude longer life than Cr-Cu in some weld schedules), x-ray tube anodes, plasma-facing components.
• CuCrZr (similar to C18150) for fusion: ITER first-wall heat-sink tubing — high thermal conductivity, retains strength after 250 °C/long-term irradiation.
• NARloy-Z (Cu-3Ag-0.5Zr): Rocketdyne-developed alloy for the SSME main-combustion-chamber liner — combines ETP-class conductivity with hot-creep resistance.
• CuNiSn spinodal (Toughmet, ToughMet 3): see §9 — Be-free high-strength copper.
• Ampcoloy 940 (Cu-2.4Ni-0.6Si-Cr): plastic-injection-mold cores and cavities — high thermal conductivity drops cycle time.

11. Lead-free machining brasses (post-2014)

NSF/ANSI 61 / NSF 372 (US drinking-water) and EU REACH SVHC and the AB1953 California / Lead-Free Plumbing Law (2014) capped lead in wetted plumbing components at 0.25 % weighted average. C36000 (3 % Pb) is no longer compliant for new potable-water fittings, so a family of lead-free machining brasses has emerged. They substitute Bi, Si, or Sb (with Sn, Mn, Ni) for the chip-breaking role of Pb:

• C69300 / EcoBrass / EnviroBrass (76Cu-21Zn-3Si): silicon brass with machinability ~85 (vs. 100 for C36000) and excellent dezincification resistance.
• C87850 (Si-brass cast equivalent): lead-free valve and faucet bodies.
• C89833 (Cu-Zn-Bi-Se): Bi+Se chip-breaking, replaces leaded yellow brass C85700.
• C49260, C49350: newer alternative Cu-Zn-Sn-Bi recipes.

The transition has also forced changes in production: Bi-bearing brasses cannot tolerate Pb contamination (forms brittle Pb-Bi at grain boundaries) so foundries either run Pb-free dedicated furnaces or accept yield penalties.

12. Comparison table — representative grades

Alloy	UNS	Composition (wt %)	UTS / 0.2 % yield, annealed (MPa)	UTS / yield, cold-worked / aged (MPa)	IACS (%)	Typical use
OFE copper	C10100	99.99 Cu	220 / 70	380 / 340 (H04)	101	Accelerator cavities, semiconductor lead-frame
ETP copper	C11000	99.90 Cu	220 / 70	380 / 340 (H04)	100	Building wire, busbar, roof sheet
DHP copper	C12200	Cu-0.02 P	220 / 70	380 / 340 (H04)	85	Plumbing/refrig tubing
Zr-Cu	C15000	Cu-0.15 Zr	220 / 70	450 / 410 (H04)	93	Resistance-weld electrode
Beryllium-copper	C17200	Cu-1.9 Be-0.25 Co	480 / 200	1380 / 1100 (TF00 H04)	22	Non-spark tools, RF springs
Cr-Cu	C18200	Cu-0.8 Cr	240 / 80	460 / 420 (TF00)	80	Weld electrodes, motor commutators
Cartridge brass	C26000	70Cu-30Zn	320 / 100	540 / 450 (H04)	28	Deep-drawn shells, radiator cores
Yellow brass	C27000	65Cu-35Zn	320 / 100	530 / 410 (H04)	27	Sheet, tube
Muntz metal	C28000	60Cu-40Zn	370 / 145	510 / 380 (H02)	28	Architectural sheet, condenser plates
Free-cutting brass	C36000	61Cu-3Pb-35Zn	340 / 125	480 / 310 (H02)	26	Plumbing fittings (legacy)
Naval brass	C46400	60Cu-39Zn-0.75 Sn	400 / 175	600 / 400 (H04)	26	Marine hardware, propeller shaft
Admiralty brass	C44300	70Cu-29Zn-1Sn-As	370 / 125	540 / 415 (H02)	25	Condenser tubing
Phosphor-bronze A	C51000	Cu-5Sn-0.2P	380 / 165	720 / 550 (H08)	15	Springs, fasteners
Phosphor-bronze D	C52400	Cu-10Sn-0.2P	460 / 195	740 / 580 (H04)	11	Heavy-duty bushings
Free-cut phos-bronze	C54400	Cu-4Sn-4Pb-4Zn	320 / 130	530 / 480 (H04)	19	Screw-machine bushings
Bearing bronze SAE 660	C93200	83-7-7-3 Cu-Sn-Pb-Zn	240 / 125 (as cast)	–	12	Sleeve bearings
High-Pb tin-bronze SAE 64	C93700	80-10-10 Cu-Sn-Pb	240 / 125 (as cast)	–	10	Slipper bearings
Aluminum-bronze	C61400	Cu-7Al-2.5 Fe	525 / 230	700 / 470 (H04)	14	Marine structural plate
NAB	C63000	Cu-10Al-5Ni-3Fe	750 / 470	815 / 510 (H02)	7	Ship propellers, valve trim
Silicon-bronze	C65500	Cu-3Si-1Mn	380 / 145	720 / 410 (H04)	7	Marine fasteners, chemical piping
Cu-Ni 90/10	C70600	88.5Cu-10Ni-1.4Fe	305 / 110	415 / 395 (H02)	9	Seawater piping
Cu-Ni 70/30	C71500	70Cu-30Ni-0.7 Fe	380 / 140	585 / 540 (H04)	5	High-velocity seawater, RN piping
Nickel-silver	C75200	65Cu-18Ni-17Zn	415 / 170	620 / 545 (H04)	6	Instrument cases, flatware
CuNiSn spinodal	C72900	Cu-15Ni-8Sn	480 / 240	1000 / 940 (TF00)	11	Be-free spring, oilfield down-hole
EnviroBrass	C69300	76Cu-21Zn-3Si	380 / 165	580 / 415 (H02)	7	Lead-free potable-water fittings

(Values are representative — see CDA “Standards Handbook” for full temper tables.)

13. Selection heuristics

• Busbar, building wire, transformer winding → C11000 ETP (or OFE C10100 if hydrogen-atmosphere brazing is needed).
• Plumbing/refrigeration tube → C12200 DHP.
• Connector spring contact → C17200 BeCu (highest yield-per-weight) or C51000 phos-bronze (lower cost, Be-free).
• Sleeve bearing (general industrial) → C93200 SAE 660.
• Sleeve bearing (marginal lube, slow speed) → C93700 high-leaded.
• Marine fastener → C65500 Si-bronze (welded structures) or C46400 naval brass (machined hardware) — never plain brass below the waterline.
• Marine propeller → C63000 NAB (commercial) or Mn-NAB variants (military, low noise).
• Seawater piping low velocity (< 4.5 m/s) → C70600 Cu-Ni 90/10.
• Seawater piping higher velocity / silty water / nuclear feedwater → C71500 Cu-Ni 70/30 or C71640.
• Non-sparking hand tool, oil-platform striker → C17200 BeCu.
• Resistance-spot-weld electrode → C18200 Cr-Cu (most), Glidcop (aerospace-grade), C17500 if higher hot strength needed.
• High-temperature heat-exchanger → C71500 (chemical), Glidcop (aerospace).
• Free-machining screw stock for potable-water fitting → C69300 EnviroBrass or C87850 (legacy C36000 only for non-wetted parts).
• Decorative “silver-looking” non-tarnish part → C75200 nickel-silver.
• Plastic-injection-mold core needing thermal conductivity → Ampcoloy 940 or Moldmax (BeCu mold grade).

14. Failure modes specific to the family

• Dezincification. Cu-Zn brasses with > 15 % Zn in stagnant, soft, or chlorinated water leach Zn preferentially, leaving spongy porous Cu. Inhibited grades (admiralty C44300, C68700 with As/Sb/P) or moves to CuNi solve it. The classic post-mortem is a brass valve body that snaps under hand torque after a year on a hot-water line.
• Stress-corrosion cracking in NH₃ / amine environments. All brasses are susceptible. Mercerised manifestation: a cold-worked brass cartridge case stored in NH₃-bearing atmosphere splits seasonally (“season cracking” — the original observation in Indian colonial-era artillery). Mitigation: stress-relief anneal at 250–300 °C after forming.
• Galvanic corrosion with steel. Copper is cathodic to carbon steel; bolting Cu/CuNi components to steel without isolation accelerates steel attack — common failure mode on flange faces in seawater service.
• Pitting & impingement of CuNi. Above the velocity rating (4.5 m/s for C70600, 6 m/s for C71500) the protective film tears and pitting follows. Design for full-flow velocity, derate for elbows.
• κ-phase precipitation in NAB. Slow cooling of C63000 through 800–500 °C precipitates Fe-rich κ-phases that nucleate corrosion. Standard NAVSEA fix: 675 °C / 4 h post-weld heat treat (“temper anneal”).
• Hydrogen embrittlement of ETP. ETP heated in H₂-bearing flames (oxyacetylene, certain furnace atmospheres) above ~370 °C suffers internal Cu₂O + H₂ → 2Cu + H₂O reaction; the steam blows microvoids. Specify OFE/OFHC or DHP for brazed assemblies.
• Mercury liquid-metal embrittlement. Brasses crack catastrophically in contact with liquid Hg or amalgams — relevant to laboratory glassware joints and historical mercury-cell process piping.
• Bi-Pb hot-shortness in lead-free brass. Lead-free brass foundries cannot allow Pb cross-contamination — Pb-Bi forms a low-melting grain-boundary phase that cracks during hot rolling.

15. Cross-references

• [[Engineering/electric-motors]] — copper windings, commutator/slip-ring alloys.
• [[Engineering/Tier3/electric-motor-taxonomy]] — brush and commutator material selection.
• [[Engineering/Tier3/bearings-taxonomy]] — bronze sleeve-bearing grades (SAE 660, SAE 64) and oil-impregnated sintered bronze.
• [[Engineering/circuit-analysis]] — % IACS / resistivity used in wire-sizing calculations.
• [[Engineering/Tier3/stainless-steels]] — galvanic compatibility tables and CuNi-vs.-CRES selection for marine service.
• [[Engineering/Tier3/fasteners-taxonomy]] — silicon-bronze, monel, and CuNi fasteners.
• [[Engineering/Tier3/surface-treatments]] — dezincification, season cracking, galvanic series.

16. Citations

• Copper Development Association, “Standards Handbook — Wrought and Cast Copper and Copper Alloy Products”, CDA pub. 7014, 2019 ed.
• ASTM B36/B36M (brass plate, sheet, strip), B96 (silicon-bronze plate), B98 (silicon-bronze rod), B100 (aluminum-bronze rolled), B88 (seamless copper water tube), B280 (ACR tube), B194 (BeCu plate), B196 (BeCu rod), B470 (CuNi rod).
• ASTM/SAE UNS — Metals and Alloys in the Unified Numbering System, 13th ed., 2017.
• J. R. Davis (ed.), “Copper and Copper Alloys”, ASM Specialty Handbook, ASM International, 2001.
• NSF/ANSI 61, NSF/ANSI 372, US Safe Drinking Water Act §1417 (lead-free wetted brass).
• NAVSEA S9074-AQ-GIB-010/278 — heat-treat requirements for nickel-aluminum-bronze.
• CDA, “Application Data Sheet — Galvanic Corrosion”, A4015.
• Schweitzer, P. A., “Corrosion Resistance Tables”, 5th ed., CRC, 2004.