Nickel silver contains no silver. These are copper-nickel-zinc alloys, and the name is purely descriptive — the nickel bleaches the red of copper to a silver-white that closely resembles sterling. They are also sold as German silver, alpaca and maillechort, and EPNS cutlery is electroplated nickel silver, where the base metal's own colour means a worn plating does not reveal an obviously different metal underneath. Colour and strength both track the nickel-to-copper ratio, from C74500 at 10% nickel with a warm pale-yellow cast, through the classic C75200 at 18%, to C77000 — whitest and strongest, reaching 1000 MPa as hard-drawn wire. Exotic Alloy supplies all eight to ASTM B122, B151 and B206.
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The C7xxxx UNS numbering invites the assumption that nickel silvers behave like C70600 and C71500. They do not. In the copper-nickels there is no zinc to lose; here there is a great deal, so dezincification applies — in stagnant or slightly acidic chloride waters the zinc can be selectively leached out, leaving a porous, mechanically worthless copper residue that retains the original shape. Nickel improves resistance substantially over plain brass but does not eliminate the mechanism. Ammonia stress-corrosion cracking — the classic ‘season cracking’ of brass — also applies, so a cold-worked or tightened component carrying residual tensile stress will crack in moist ammonia, ammonium compounds, amines or nitrites.
Nickel silvers are not seawater alloys. They carry none of the deliberate iron addition that builds the protective film in the marine copper-nickels, and should not be specified for seawater piping, condenser tube or any flowing-seawater duty. Their corrosion credentials are for atmospheric exposure, indoor and decorative service, food contact and freshwater — duties in which they perform well and tarnish slowly. A stress-relief anneal after cold work is genuinely important on these alloys rather than a refinement, and it matters most on spring components, which are by definition held under the sustained stress that SCC requires.
Every grade here is rated Poor for hot forming, and that governs how parts are made. Nickel silvers are hot-short: the zinc volatilises and the alloys crack rather than flow at forging temperature. They are cold-worked materials, rated Excellent for cold working to match, so components are blanked, drawn, spun, stamped, cold headed and roll-threaded from strip, rod or wire with interstage annealing where the work is severe. Hot forging, hot extrusion and hot rolling are not practical routes — design the part for cold forming from the outset.
Machining is poor unless you specify a leaded grade, and welding is limited either way. The unleaded alloys rate 20 on the CDA machinability scale, the same as pure copper; C78200 with 1.5–2.5% lead reaches 60, three times better, and C79200 is the other free-machining option. On joining, the unleaded grades solder and braze Excellently but CDA rate gas-shielded arc welding only Fair and coated metal arc welding Not Recommended; on the leaded grades almost every welding process is Not Recommended. Zinc fume is a health hazard — zinc oxide causes metal fume fever, so extraction is required whenever these alloys are heated to brazing or welding temperature.
No nickel silver is covered by ASTM F468 or F467. Those standards carry C11000, C26000, C27000, C46200, C46400, C51000, C61300, C61400, C63000, C64200, C65100, C65500, C66100, C67500, C71000 and C71500 — none of the C73xxx to C79xxx nickel silvers appears. Components are manufactured to ASTM B122, B151 or B206 with thread conformance to the relevant ASME or ISO standard. In practice these alloys are rarely specified as structural fasteners anyway: they are chosen for appearance, spring properties, tarnish resistance and formability. Finally, note that lead in C78200 and C79200 is regulated in drinking-water contact components and under RoHS — confirm the position for your market before committing a design.
Nickel silvers are cold-worked alloys — every grade is rated Poor for hot forming because the zinc volatilises and the metal cracks rather than flows at forging temperature, and Excellent for cold working to compensate. Exotic Alloy blanks, draws, spins, stamps, cold heads and roll-threads these alloys from strip, rod and wire with interstage annealing where the work demands it, setting the final temper by the last cold reduction. Machining is the weak point: the unleaded grades rate 20 on the CDA scale, gummy and prone to built-up edge, so where machining dominates we recommend the leaded C78200 at a rating of 60. Soldering and brazing are rated Excellent across the unleaded range and are the preferred joining routes, which suits the decorative and instrument work these alloys are used for — always with zinc fume extraction in place.
All data from the Copper Development Association alloy records. Colour and strength both track the nickel-to-copper ratio; annealed and hardest figures are CDA typical values for flat product unless noted.
| Grade | Designation | Copper | Nickel | Lead | Strength Range | Machinability | Chosen For |
|---|---|---|---|---|---|---|---|
| C73500 | 72-18 | 70.5–73.5% | 16.5–19.5% | 0.09% max | 379–579 MPa | 20 | Coinage; best corrosion resistance here |
| C74500 | 65-10 | 63.5–66.5% | 9.0–11.0% | 0.09% max* | 338–896 MPa | 20 | Most economical; warmest colour |
| C75200 | 65-18 | 63.0–66.5% | 16.5–19.5% | 0.05% max | 386–710 MPa | 20 | The classic German silver — EPNS base |
| C75400 | 65-15 | 63.5–66.5% | 14.0–16.0% | 0.10% max | 365–634 MPa | 20 | Mid-range colour and cost |
| C75700 | 65-12 | 63.5–66.5% | 11.0–13.0% | 0.05% max | 359–641 MPa | 20 | Economical mid-nickel grade |
| C77000 | 55-18 | 53.5–56.5% | 16.5–19.5% | 0.05% max | 414–1000 MPa | 30 | Whitest and strongest — springs |
| C78200 | 65-8-2 leaded | 63.0–67.0% | 7.0–9.0% | 1.5–2.5% | 365–627 MPa | 60 | Free machining |
| C79200 | Leaded 12% Ni | 59.0–66.5% | 11.0–13.0% | 0.8–1.4% | On request | Free machining | Lock pins, EKG electrodes |
Read the nickel column for colour and the copper column for strength. Nickel bleaches copper towards silver-white, so colour improves steadily from C74500 at 10% to the 18% grades. But C75200 and C77000 carry the same 16.5–19.5% nickel and behave very differently, because C77000 holds it against only 53.5–56.5% copper — roughly 27% zinc against 17% — which makes it both whiter and far stronger, reaching 1000 MPa as hard-drawn wire. That also makes C77000 the most zinc-rich alloy here and therefore the most exposed to dezincification and ammonia stress-corrosion cracking, which matters because its main use is springs, held permanently under the sustained stress SCC requires. *Lead in C74500 is limited to 0.05% for rod, wire and tube; the 0.09% figure applies to flat product. The two highlighted grades are the leaded free-machining options — three times the cutting performance, at the cost of weldability and with lead restricted in drinking-water and RoHS applications. No mechanical data is published by CDA for C79200, so that page carries an on-request note rather than figures we cannot attribute.
We are committed to delivering zero-defect nickel silver components and fixings. All products undergo rigorous testing including PMI (Positive Material Identification), chemical analysis with nickel and zinc reported explicitly — nickel governs colour, zinc governs dezincification susceptibility — lead certified on the free-machining grades, mechanical verification against the specified temper, dimensional inspection and full traceability with EN 10204 3.1 certification. Colour matching against a supplied sample is available where appearance is a specified requirement.
Exotic Alloy exports nickel silver strip, rod, wire and formed components to cutlery, musical instrument, optical, decorative hardware, coinage and electrical contact clients worldwide. Our dedicated logistics team ensures secure export packaging and timely deliveries by sea and air freight with full customs documentation support.