Copper Alloy C76400-H04
Supply condition · default condition
UNS C76400
H04 = full hard
The standard stock temper for flat springs, contacts and stamped structural strip where high yield strength is the priority.
Values for the H04 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 | — |
H04DefaultThis page 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 | — |
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-H04?
C76400-H04 is C76400 supplied in the H04 condition — the standard stock temper for flat springs, contacts and stamped structural strip where high yield strength is the priority. C76400-H04 has a yield strength of 510 MPa (74 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 90% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 125 GPa (18.1 Msi). C76400-H04 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).
Advantages
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
- High strength — 510 MPa (74 ksi), better than 90% of copper alloy grades
Limitations
- Limited ductility — 4%, worse than 96% of copper alloy grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 93% of copper alloy grades
- Low electrical conductivity — 6 % IACS, worse than 93% of copper alloy grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 89% of copper alloy grades
C76400-H04 properties
Typical room-temperature values for C76400-H04; 11 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-H04 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-H04 has a yield strength of 510 MPa (74 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 90% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 125 GPa (18.1 Msi).
Thermal5
C76400-H04 is rated for continuous service to 200°C (392 °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
C76400-H04 conducts electricity at 6 % IACS, worse than 93% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C76400-H04 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-H04's machinability is poor (30/100, worse than 67% of copper alloy grades); weldability good (55/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C76400-H04
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-H04 — frequently asked
What is C76400-H04 used for?
C76400-H04 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-H04?
C76400-H04 has a typical yield strength of 510 MPa (74 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 90% of copper alloy grades. Strength varies by condition: see the 7 listed tempers.
Is C76400-H04 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 67% 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-H04 be welded?
Yes — weldability is rated good (55/100). 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-H04?
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-H04 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-H04?
C76400-H04 is rated for continuous use to about 200°C (392 °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.