Copper Alloy C74500-H08
Supply condition
UNS C74500
H08 = spring hard
Spring-temper strip for contact springs, diaphragms and snap parts; bend only with generous radii and grain-direction control.
Values for the H08 condition
Other C74500 tempers and conditions
C74500 is listed in 8 conditions; see the grade overview at C74500.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for deep drawing, severe bending and spinning where maximum ductility is needed. | 155 | 385 | 40 | 95 HB | 9 % IACS |
As hot rolled | Hot-rolled plate/bar stock for machined or further-worked parts where temper control is not critical. | 170 | 400 | 35 | 100 HB | — |
Quarter hard | Choose when moderate strength must be combined with substantial bending/forming ability. | 340 | 450 | 20 | 130 HB | — |
H02Default Half hard | The general-purpose stocked strip temper: good balance of strength, flatness and forming for hardware and decorative parts. | 400 | 510 | 12 | 150 HB | — |
Full hard | Use for stamped flat parts and light spring contacts needing high strength with only gentle bends. | 515 | 585 | 4 | 175 HB | — |
Extra hard | For flat springs, clips and blanked parts where stiffness and yield strength dominate over formability. | 590 | 650 | 3 | 190 HB | — |
H08This page Spring hard | Spring-temper strip for contact springs, diaphragms and snap parts; bend only with generous radii and grain-direction control. | 635 | 690 | 2 | 200 HB | — |
Extra spring hard | Maximum-strength cold-rolled strip for highly stressed flat springs; essentially no formability. | 675 | 725 | 2 | 17 HRC | 8.5 % IACS |
What is C74500-H08?
C74500-H08 is C74500 supplied in the H08 condition — spring-temper strip for contact springs, diaphragms and snap parts; bend only with generous radii and grain-direction control. C74500-H08 has a yield strength of 635 MPa (92.1 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 127 GPa (18.4 Msi). C74500-H08 has a density of 8.73 g/cm³ (0.315 lb/in³), lighter than 53% of copper alloy grades. It melts at 954°C (1,749 °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 — 635 MPa (92.1 ksi), better than 95% of copper alloy grades
Limitations
- Limited service temperature — 140°C (284 °F), worse than 100% of copper alloy grades
- Limited ductility — 2%, worse than 98% of copper alloy grades
- High embodied carbon — 5.2 kg CO₂/kg, worse than 88% 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
C74500-H08 properties
Typical room-temperature values for C74500-H08; 12 are specific to this condition. Other listed values are C74500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C74500-H08 has a density of 8.73 g/cm³ (0.315 lb/in³), lighter than 53% of copper alloy grades. It melts at 954°C (1,749 °F).
Mechanical12
C74500-H08 has a yield strength of 635 MPa (92.1 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 2% and the elastic modulus is 127 GPa (18.4 Msi).
Thermal6
C74500-H08 is rated for continuous service to 140°C (284 °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
C74500-H08 conducts electricity at 9 % IACS, worse than 78% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C74500-H08 takes about 78 MJ of energy and emits 5.2 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 40%.
Manufacturability7
C74500-H08's machinability is poor (33/100, worse than 53% of copper alloy grades); weldability fair (40/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C74500-H08
Is C74500 easy to machine?
Machinability only ~20% of free-cutting brass — gummy, long chips; use sharp positive-rake tools, high speed, low feed and generous lubrication; leaded nickel silvers (C79300) are preferable for screw-machine work.
Can C74500 be welded?
Arc/gas fusion welding is poor because zinc fumes and volatilises; resistance spot/seam welding is good and silver brazing or soldering is excellent — use ventilation and low-zinc filler when fusion joining is unavoidable.
Can C74500 be formed, bent or molded?
Excellent cold formability in O61/H01 (deep drawing, spinning, coining); interanneal ~600–700 °C, and stress-relieve cold-worked parts at ~250–300 °C to avoid ammonia-related stress-corrosion cracking.
What surface finishes work on C74500?
Takes a bright white mirror polish directly and is a standard base for nickel, chrome, silver or gold plating; lacquer or clear coat outdoors to prevent slow tarnish — cannot be anodized.
C74500 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 incl. Ag | 63.5 – 66.5 | 65 |
| NiNi + Co | 9 – 11 | 10 |
| Pb | ≤ 0.1 | — |
| Fe | ≤ 0.25 | — |
| Mn | ≤ 0.5 | — |
| Znremainder, ~25% | balance | — |
C74500-H08 — frequently asked
What is C74500-H08 used for?
C74500-H08 is typically used for zippers, eyeglass frames, hardware, electrical connectors and nameplates. In short: classic 65-10 nickel silver; bright white plating base; not for screw machining.
What is the yield strength of C74500-H08?
C74500-H08 has a typical yield strength of 635 MPa (92.1 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 95% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C74500-H08 easy to machine?
Not especially — machinability is rated poor (33/100, worse than 53% of copper alloy grades). Machinability only ~20% of free-cutting brass — gummy, long chips; use sharp positive-rake tools, high speed, low feed and generous lubrication; leaded nickel silvers (C79300) are preferable for screw-machine work.
Can C74500-H08 be welded?
With care — weldability is rated fair (40/100). Arc/gas fusion welding is poor because zinc fumes and volatilises; resistance spot/seam welding is good and silver brazing or soldering is excellent — use ventilation and low-zinc filler when fusion joining is unavoidable.
What surface finishes work on C74500-H08?
Takes a bright white mirror polish directly and is a standard base for nickel, chrome, silver or gold plating; lacquer or clear coat outdoors to prevent slow tarnish — cannot be anodized.
Can C74500-H08 be formed, bent or molded?
Excellent cold formability in O61/H01 (deep drawing, spinning, coining); interanneal ~600–700 °C, and stress-relieve cold-worked parts at ~250–300 °C to avoid ammonia-related stress-corrosion cracking.
What is the maximum service temperature of C74500-H08?
C74500-H08 is rated for continuous use to about 140°C (284 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C74500-H02 and C74500-H10?
H02 is the default condition — the general-purpose stocked strip temper: good balance of strength, flatness and forming for hardware and decorative parts. H10: maximum-strength cold-rolled strip for highly stressed flat springs; essentially no formability. Yield strength is 400 MPa in H02 versus 675 MPa in H10.
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 (2021)
- CDA Alloy Database — C74500 property sheet — 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.