Copper Alloy C76400-H10
Supply condition
UNS C76400
H10 = extra spring hard
Maximum-strength strip/wire for flat springs and pretensioned contacts; essentially no formability across the grain.
Values for the H10 condition
Other C76400 tempers and conditions
C76400 is listed in 7 conditions; see the grade overview at C76400.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose for deep drawing, spinning and severe forming before a final age/stress-relief or plating step. | 170 | 390 | 40 | 90 HB | — |
Quarter hard | Choose when moderate strength must be combined with residual bending/forming ability. | 340 | 450 | 20 | 120 HB | — |
Half hard | General-purpose strip temper for stamped parts needing strength plus light bending. | 425 | 515 | 12 | 145 HB | — |
H04Default Full hard | The standard stock temper for flat springs, contacts and stamped structural strip where high yield strength is the priority. | 510 | 585 | 4 | 165 HB | — |
Extra hard | Choose for flat springs and blanked parts with only very gentle forming after rolling. | 570 | 655 | 3 | 180 HB | — |
Spring hard | Choose for springy contacts and clips loaded near the elastic limit; forming limited to large-radius bends with grain direction. | 620 | 705 | 2 | 195 HB | — |
H10This page Extra spring hard | Maximum-strength strip/wire for flat springs and pretensioned contacts; essentially no formability across the grain. | 670 | 750 | 2 | 20 HRC | 5.5 % IACS |
What is C76400-H10?
C76400-H10 is C76400 supplied in the H10 condition — maximum-strength strip/wire for flat springs and pretensioned contacts; essentially no formability across the grain. C76400-H10 has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 127 GPa (18.4 Msi). C76400-H10 has a density of 8.7 g/cm³ (0.314 lb/in³), lighter than 56% of copper alloy grades. It melts at 1,040°C (1,904 °F). H04 is the default condition FabDigit quotes; H10 is available on request or by drawing note.
Advantages
- High strength — 670 MPa (97.2 ksi), better than 96% of copper alloy grades
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
Limitations
- Limited ductility — 2%, worse than 98% of copper alloy grades
- Poor heat conductor — 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 96% of copper alloy grades
- Low electrical conductivity — 5.5 % IACS, worse than 95% of copper alloy grades
- Limited service temperature — 175°C (347 °F), worse than 92% of copper alloy grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 89% of copper alloy grades
C76400-H10 properties
Typical room-temperature values for C76400-H10; 22 are specific to this condition. Other listed values are C76400 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C76400-H10 has a density of 8.7 g/cm³ (0.314 lb/in³), lighter than 56% of copper alloy grades. It melts at 1,040°C (1,904 °F).
Mechanical12
C76400-H10 has a yield strength of 670 MPa (97.2 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 96% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 127 GPa (18.4 Msi).
Thermal5
C76400-H10 is rated for continuous service to 175°C (347 °F). It conducts heat at 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 96% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C76400-H10 conducts electricity at 5.5 % IACS, worse than 95% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (64/100), better than 52% of copper alloy grades.
Sustainability4
Producing a kilogram of C76400-H10 takes about 78 MJ of energy and emits 5.5 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 40%.
Manufacturability8
C76400-H10's machinability is fair (35/100, better than 51% of copper alloy grades); weldability fair (45/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C76400-H10
Is C76400 easy to machine?
Tough, gummy chips — use sharp positive-rake carbide, moderate speed with good coolant; free-machining leaded nickel silver (C79xxx) is preferable for screw-machine work.
Can C76400 be welded?
Best joined by resistance welding, silver brazing or soldering; fusion welding causes zinc fuming and porosity, so use low heat input and ventilation.
Can C76400 be formed, bent or molded?
Excellent deep-drawing and stamping in O61/H01; cold-worked tempers work-harden fast — interstage anneal near 600–750 °C and stress-relieve formed springs at ~250 °C.
What surface finishes work on C76400?
Takes a bright silver-white polish and readily accepts nickel, chrome, silver or gold plating; lacquer or plate for long-term tarnish resistance.
C76400 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 |
|---|---|---|
| Cuincludes Ag when reported | 58.5 – 61.5 | 60 |
| NiNi + Co | 16.5 – 19.5 | 18 |
| Pb | ≤ 0.05 | — |
| Fe | ≤ 0.25 | — |
| Mn | ≤ 0.5 | — |
| Znremainder, ≈22 % | balance | — |
C76400-H10 — frequently asked
What is C76400-H10 used for?
C76400-H10 is typically used for electrical contacts, springs, hardware and musical instrument parts. In short: spring-temper nickel silver; highest hardness, low elongation; strip and wire grade.
What is the yield strength of C76400-H10?
C76400-H10 has a typical yield strength of 670 MPa (97.2 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 96% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C76400-H10 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Tough, gummy chips — use sharp positive-rake carbide, moderate speed with good coolant; free-machining leaded nickel silver (C79xxx) is preferable for screw-machine work.
Can C76400-H10 be welded?
With care — weldability is rated fair (45/100). Best joined by resistance welding, silver brazing or soldering; fusion welding causes zinc fuming and porosity, so use low heat input and ventilation.
What surface finishes work on C76400-H10?
Takes a bright silver-white polish and readily accepts nickel, chrome, silver or gold plating; lacquer or plate for long-term tarnish resistance.
Can C76400-H10 be formed, bent or molded?
Excellent deep-drawing and stamping in O61/H01; cold-worked tempers work-harden fast — interstage anneal near 600–750 °C and stress-relieve formed springs at ~250 °C.
What is the maximum service temperature of C76400-H10?
C76400-H10 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C76400-H04 and C76400-O61?
H04 is the default condition — the standard stock temper for flat springs, contacts and stamped structural strip where high yield strength is the priority. O61: choose for deep drawing, spinning and severe forming before a final age/stress-relief or plating step. Yield strength is 510 MPa in H04 versus 170 MPa in O61.
Sources
- ASTM B122/B122M — Copper-Nickel-Zinc (Nickel Silver) Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- ASTM B206/B206M — Copper-Nickel-Zinc (Nickel Silver) Wire — ASTM International (2019)
- CDA Alloy Datasheet C76400 (UNS composition, temper and physical property tables) — Copper Development Association (2023)
- 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.