Copper Alloy C77000-H08
Supply condition
UNS C77000 · EN CW410J
H08 = spring hard
Standard choice for flat springs, contact fingers and diaphragms needing maximum elastic limit with good tarnish resistance.
Values for the H08 condition
Other C77000 tempers and conditions
C77000 is listed in 8 conditions; see the grade overview at C77000.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.035 mm grain size | Softest commercial condition for deep drawing, spinning and severe forming before final work-hardening. | 186 | 414 | 40 | 100 HB | 5.7 % IACS |
As hot rolled | Hot-rolled plate/bar stock for subsequent machining or forming where temper is not critical. | 205 | 435 | 35 | 62 HRB | — |
Quarter hard | Light cold work when moderate strength must be combined with continued bending and drawing ability. | 400 | 483 | 25 | 76 HRB | — |
H02Default Half hard | Most widely stocked strip/sheet temper: good balance of strength, formability and flatness for hardware and contacts. | 505 | 565 | 12 | 84 HRB | — |
Full hard | High-strength flat stock for stamped parts with only gentle bends, and for wear-resistant decorative trim. | 585 | 655 | 4 | 89 HRB | — |
Extra hard | Use where near-spring strength is needed but full spring temper flatness is not required. | 655 | 725 | 3 | 92 HRB | — |
H08This page Spring hard | Standard choice for flat springs, contact fingers and diaphragms needing maximum elastic limit with good tarnish resistance. | 710 | 790 | 2 | 95 HRB | — |
Extra spring hard | Maximum-strength strip for thin, highly stressed springs formed with very generous bend radii only. | 745 | 825 | 2 | 19 HRC | 5.3 % IACS |
What is C77000-H08?
C77000-H08 is C77000 supplied in the H08 condition — standard choice for flat springs, contact fingers and diaphragms needing maximum elastic limit with good tarnish resistance. C77000-H08 has a yield strength of 710 MPa (103 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 124 GPa (18 Msi). C77000-H08 has a density of 8.72 g/cm³ (0.315 lb/in³), lighter than 54% of copper alloy grades. It melts at 1,010°C (1,850 °F). H02 is the default condition FabDigit quotes; H08 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 90/100, better than 99% of copper alloy grades
- High strength — 710 MPa (103 ksi), better than 97% of copper alloy grades
Limitations
- Limited ductility — 2%, worse than 98% of copper alloy grades
- Limited service temperature — 150°C (302 °F), worse than 96% of copper alloy grades
- Low electrical conductivity — 5.5 % IACS, worse than 95% of copper alloy grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 91% of copper alloy grades
C77000-H08 properties
Typical room-temperature values for C77000-H08; 10 are specific to this condition. Other listed values are C77000 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C77000-H08 has a density of 8.72 g/cm³ (0.315 lb/in³), lighter than 54% of copper alloy grades. It melts at 1,010°C (1,850 °F).
Mechanical12
C77000-H08 has a yield strength of 710 MPa (103 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 124 GPa (18 Msi).
Thermal6
C77000-H08 is rated for continuous service to 150°C (302 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C77000-H08 conducts electricity at 5.5 % IACS, worse than 95% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C77000-H08 takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 35%.
Manufacturability7
C77000-H08's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability fair (40/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C77000-H08
Is C77000 easy to machine?
Tough and gummy (≈20% of free-cutting brass) — use sharp positive-rake carbide, rigid setups, moderate speeds and generous coolant; consider leaded C79200 if turning volume is high.
Can C77000 be welded?
Resistance and GTAW welding are workable with low heat input; oxy-fuel welding is poor due to zinc fume loss, and soldering/silver brazing are the preferred joining routes.
Can C77000 be formed, bent or molded?
Excellent cold formability in OS035/H01 with interstage anneals at 600–750 °C; hot working is limited, and cold-worked parts should be stress-relieved (~260 °C) to avoid ammonia SCC.
What surface finishes work on C77000?
Takes a bright silver-white polish and accepts nickel, chrome, silver and gold plating readily; lacquer or clear coat for long-term tarnish protection — anodizing does not apply.
C77000 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CuCu + sum of named elements ≥ 99.5% | 53.5 – 56.5 | 55 |
| NiNi includes Co | 16.5 – 19.5 | 18 |
| Pbunleaded grade | ≤ 0.05 | — |
| Fe | ≤ 0.25 | — |
| Mn | ≤ 0.5 | — |
| Znremainder, nominally ~27% | balance | — |
C77000-H08 — frequently asked
What is C77000-H08 used for?
C77000-H08 is typically used for springs, silverware base metal for plating, zippers, marine hardware and musical instrument fittings. In short: strongest unleaded nickel silver; spring and zipper grade; high-nickel, high-zinc strip.
What is the yield strength of C77000-H08?
C77000-H08 has a typical yield strength of 710 MPa (103 ksi) and a tensile strength of 790 MPa (115 ksi) — stronger than 97% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C77000-H08 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Tough and gummy (≈20% of free-cutting brass) — use sharp positive-rake carbide, rigid setups, moderate speeds and generous coolant; consider leaded C79200 if turning volume is high.
Can C77000-H08 be welded?
With care — weldability is rated fair (40/100). Resistance and GTAW welding are workable with low heat input; oxy-fuel welding is poor due to zinc fume loss, and soldering/silver brazing are the preferred joining routes.
What surface finishes work on C77000-H08?
Takes a bright silver-white polish and accepts nickel, chrome, silver and gold plating readily; lacquer or clear coat for long-term tarnish protection — anodizing does not apply.
Can C77000-H08 be formed, bent or molded?
Excellent cold formability in OS035/H01 with interstage anneals at 600–750 °C; hot working is limited, and cold-worked parts should be stress-relieved (~260 °C) to avoid ammonia SCC.
What is the maximum service temperature of C77000-H08?
C77000-H08 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C77000-H02 and C77000-OS035?
H02 is the default condition — most widely stocked strip/sheet temper: good balance of strength, formability and flatness for hardware and contacts. OS035: softest commercial condition for deep drawing, spinning and severe forming before final work-hardening. Yield strength is 505 MPa in H02 versus 186 MPa in OS035.
Sources
- CDA Alloy Datasheet C77000 (Nickel Silver 55-18) — Copper Development Association (2023)
- ASTM B122/B122M Copper-Nickel-Zinc (Nickel Silver) Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- ASTM B151/B151M Copper-Nickel-Zinc and Copper-Nickel Rod and Bar — ASTM International (2020)
- EN 12163 / EN 1652 CuNi18Zn27 (CW410J) — CEN (2016)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.