Copper Alloy C75700-H04
Supply condition
UNS C75700 · EN CW403J
H04 = full hard
Pick for flat springs, contacts and stiff hardware where high strength matters more than bend radius.
Values for the H04 condition
Other C75700 tempers and conditions
C75700 is listed in 8 conditions; see the grade overview at C75700.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for deep drawing, spinning and severe forming where maximum ductility is needed. | 152 | 365 | 42 | 75 HB | 9 % IACS |
Quarter hard | Pick when moderate bending/forming must be combined with higher strength than annealed strip. | 330 | 434 | 20 | 110 HB | — |
H02Default Half hard | General-purpose stocked strip temper: balanced strength and bendability for hardware, frames and stampings. | 420 | 496 | 10 | 135 HB | — |
H04This page Full hard | Pick for flat springs, contacts and stiff hardware where high strength matters more than bend radius. | 505 | 565 | 4 | 165 HB | — |
Extra hard | Pick for higher-load spring strip formed only with generous bend radii along the grain. | 560 | 620 | 3 | 180 HB | 8.5 % IACS |
Hard drawn | Cold-drawn wire condition for spectacle-frame wire, springs and formed wire parts. | 590 | 655 | 3 | 190 HB | 8.5 % IACS |
Spring hard | Pick for flat springs, clips and contact fingers requiring high elastic limit. | 620 | 675 | 2 | 195 HB | 8.5 % IACS |
Extra spring hard | Maximum-strength rolled strip for demanding spring contacts; essentially no formability across grain. | 660 | 710 | 2 | 208 HB | 8.5 % IACS |
What is C75700-H04?
C75700-H04 is C75700 supplied in the H04 condition — pick for flat springs, contacts and stiff hardware where high strength matters more than bend radius. C75700-H04 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 90% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 124 GPa (18 Msi). C75700-H04 has a density of 8.72 g/cm³ (0.315 lb/in³), lighter than 54% of copper alloy grades. It melts at 1,004°C (1,839 °F). H02 is the default condition FabDigit quotes; H04 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 — 505 MPa (73.2 ksi), better than 90% of copper alloy grades
Limitations
- Limited ductility — 4%, worse than 96% of copper alloy grades
- High embodied carbon — 4.6 kg CO₂/kg, worse than 82% of copper alloy grades
- Low electrical conductivity — 9 % IACS, worse than 78% of copper alloy grades
- Poor heat conductor — 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades
C75700-H04 properties
Typical room-temperature values for C75700-H04; 12 are specific to this condition. Other listed values are C75700 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C75700-H04 has a density of 8.72 g/cm³ (0.315 lb/in³), lighter than 54% of copper alloy grades. It melts at 1,004°C (1,839 °F).
Mechanical12
C75700-H04 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 90% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 124 GPa (18 Msi).
Thermal6
C75700-H04 is rated for continuous service to 180°C (356 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C75700-H04 conducts electricity at 9 % IACS, worse than 78% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), better than 58% of copper alloy grades.
Sustainability4
Producing a kilogram of C75700-H04 takes about 65 MJ of energy and emits 4.6 kg of CO₂ — more than 81% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C75700-H04's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability fair (40/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C75700-H04
Is C75700 easy to machine?
Machinability ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake carbide, moderate speed and generous coolant.
Can C75700 be welded?
Resistance and brazing/soldering are preferred; fusion welding risks zinc fume and porosity, so use low-heat processes with adequate ventilation.
Can C75700 be formed, bent or molded?
Excellent cold formability in O61/H01 for deep drawing and stamping; interanneal between heavy reductions and stress-relieve at ~250–300 °C to avoid ammonia-induced SCC.
What surface finishes work on C75700?
Takes a bright silver-white polish and readily accepts Ni, Cr, Ag or Au plating; lacquer or clearcoat for long-term tarnish protection — not anodizable.
C75700 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 if reported | 63.5 – 66.5 | 65 |
| NiNi + Co | 11 – 13 | 12 |
| Pb | ≤ 0.05 | — |
| Fe | ≤ 0.25 | — |
| Mn | ≤ 0.5 | — |
| Zn | balance | — |
C75700-H04 — frequently asked
What is C75700-H04 used for?
C75700-H04 is typically used for optical frame components, hardware, nameplates and electrical parts. In short: mid-nickel strip grade; good cold workability; silvery-white stamping alloy.
What is the yield strength of C75700-H04?
C75700-H04 has a typical yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 90% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C75700-H04 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Machinability ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake carbide, moderate speed and generous coolant.
Can C75700-H04 be welded?
With care — weldability is rated fair (40/100). Resistance and brazing/soldering are preferred; fusion welding risks zinc fume and porosity, so use low-heat processes with adequate ventilation.
What surface finishes work on C75700-H04?
Takes a bright silver-white polish and readily accepts Ni, Cr, Ag or Au plating; lacquer or clearcoat for long-term tarnish protection — not anodizable.
Can C75700-H04 be formed, bent or molded?
Excellent cold formability in O61/H01 for deep drawing and stamping; interanneal between heavy reductions and stress-relieve at ~250–300 °C to avoid ammonia-induced SCC.
What is the maximum service temperature of C75700-H04?
C75700-H04 is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C75700-H02 and C75700-O61?
H02 is the default condition — general-purpose stocked strip temper: balanced strength and bendability for hardware, frames and stampings. O61: pick for deep drawing, spinning and severe forming where maximum ductility is needed. Yield strength is 420 MPa in H02 versus 152 MPa in O61.
Sources
- 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)
- CDA Alloy Datasheet C75700 (Nickel Silver 65-12) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- EN 1652 / CW403J CuNi12Zn24 — CEN (1997)
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.