Copper Alloy C72500-H06
Supply condition
UNS C72500 · EN CW351H, CuNi9Sn2
H06 = extra hard
Pick when high spring force is needed and forming is limited to gentle good-way bends.
Values for the H06 condition
Other C72500 tempers and conditions
C72500 is listed in 10 conditions; see the grade overview at C72500.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for deep drawing, severe forming or as the starting stock before customer-side stamping and stress relief. | 150 | 380 | 35 | 45 HRB | 11.5 % IACS |
As hot rolled | Pick for heavier plate/bar stock where no cold-rolled temper is required and further machining or forming follows. | 180 | 410 | 30 | 50 HRB | 11.5 % IACS |
Quarter hard | Pick when moderate strength must be combined with tight-radius bending in both grain directions. | 400 | 470 | 15 | 66 HRB | 11 % IACS |
H02Default Half hard | Default stocked strip temper: balanced strength and formability for stamped connector shells, lead frames and terminals. | 480 | 530 | 9 | 76 HRB | 11 % IACS |
Full hard | Pick for contact springs and clips needing higher yield and stress-relaxation resistance with simple, mostly good-way bends. | 550 | 590 | 5 | 83 HRB | 11 % IACS |
H04 + stress relieved | Pick when formed springs must keep contact force at 100–150 °C; a low-temperature bake raises yield slightly and cuts stress relaxation. | 580 | 610 | 6 | 187 HB | 11.5 % IACS |
H06This page Extra hard | Pick when high spring force is needed and forming is limited to gentle good-way bends. | 605 | 640 | 4 | 87 HRB | 11 % IACS |
Spring hard | Pick for high-force contact springs and washers where bend radii are generous and stress relief follows forming. | 655 | 690 | 3 | 90 HRB | 11 % IACS |
Extra spring hard | Pick for thin-gauge, high-deflection springs where maximum yield strength outweighs formability. | 690 | 725 | 2.5 | 92 HRB | 11 % IACS |
Strain hardened, half hard | Pick for the highest available strength in thin strip; forming must be limited to flat blanking or very light bends. | 725 | 760 | 2 | 94 HRB | 11 % IACS |
What is C72500-H06?
C72500-H06 is C72500 supplied in the H06 condition — pick when high spring force is needed and forming is limited to gentle good-way bends. C72500-H06 has a yield strength of 605 MPa (87.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 94% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 138 GPa (20 Msi). C72500-H06 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,060°C (1,940 °F). H02 is the default condition FabDigit quotes; H06 is available on request or by drawing note.
Advantages
- Stiff — 138 GPa (20 Msi), better than 95% of copper alloy grades
- High strength — 605 MPa (87.7 ksi), better than 94% of copper alloy grades
Limitations
- Limited ductility — 4%, worse than 96% of copper alloy grades
- Limited service temperature — 150°C (302 °F), worse than 96% of copper alloy grades
- Poor heat conductor — 45 W/m·K (26 BTU/hr·ft·°F), worse than 76% of copper alloy grades
C72500-H06 properties
Typical room-temperature values for C72500-H06; 11 are specific to this condition. Other listed values are C72500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C72500-H06 has a density of 8.89 g/cm³ (0.321 lb/in³), heavier than 72% of copper alloy grades. It melts at 1,060°C (1,940 °F).
Mechanical11
C72500-H06 has a yield strength of 605 MPa (87.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 94% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 138 GPa (20 Msi).
Thermal5
C72500-H06 is rated for continuous service to 150°C (302 °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
C72500-H06 conducts electricity at 11 % IACS, worse than 68% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 76% of copper alloy grades.
Sustainability4
Producing a kilogram of C72500-H06 takes about 62 MJ of energy and emits 4.2 kg of CO₂ — more than 76% of copper alloy grades. Typical recycled content is 30%.
Manufacturability7
C72500-H06's machinability is poor (33/100, worse than 53% of copper alloy grades); weldability good (55/100); formability fair (38/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C72500-H06
Is C72500 easy to machine?
Gummy, low machinability (~20–30 % of free-cutting brass): use sharp, positive-rake carbide, high coolant flow and moderate speeds; harder tempers chip more cleanly than annealed.
Can C72500 be welded?
Resistance and laser welding are good; GTAW/GMAW possible with Cu-Ni filler but keep heat input low and avoid oxide/sulphur pickup — soldering and brazing are the preferred joining routes.
Can C72500 be formed, bent or molded?
Anneal or H01/H02 for deep drawing and tight bends; in H06–H14 restrict to good-way bends with generous radii and stress-relieve formed springs at 200–260 °C.
What surface finishes work on C72500?
Not anodizable; solders and plates readily with Sn, Ni, Ag or Au — Ni underplate is common for lead frames, and bright-rolled strip polishes to a warm silver-grey finish.
C72500 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 |
|---|---|---|
| Niincluding Co | 8.5 – 10.5 | 9.5 |
| Sn | 1.8 – 2.8 | 2.3 |
| Fe | ≤ 0.6 | 0.1 |
| Mn | ≤ 0.2 | 0.05 |
| Zn | ≤ 0.5 | — |
| Pb | ≤ 0.05 | — |
| CuCu + named elements 99.8 % min | balance | — |
C72500-H06 — frequently asked
What is C72500-H06 used for?
C72500-H06 is typically used for connectors, relay springs, lead frames and switch contacts. In short: beryllium-free spring alloy; good stress-relaxation resistance; solders and plates easily.
What is the yield strength of C72500-H06?
C72500-H06 has a typical yield strength of 605 MPa (87.7 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 94% of copper alloy grades. Strength varies by condition: see the 10 listed tempers.
Is C72500-H06 easy to machine?
Not especially — machinability is rated poor (33/100, worse than 53% of copper alloy grades). Gummy, low machinability (~20–30 % of free-cutting brass): use sharp, positive-rake carbide, high coolant flow and moderate speeds; harder tempers chip more cleanly than annealed.
Can C72500-H06 be welded?
Yes — weldability is rated good (55/100). Resistance and laser welding are good; GTAW/GMAW possible with Cu-Ni filler but keep heat input low and avoid oxide/sulphur pickup — soldering and brazing are the preferred joining routes.
What surface finishes work on C72500-H06?
Not anodizable; solders and plates readily with Sn, Ni, Ag or Au — Ni underplate is common for lead frames, and bright-rolled strip polishes to a warm silver-grey finish.
Can C72500-H06 be formed, bent or molded?
Anneal or H01/H02 for deep drawing and tight bends; in H06–H14 restrict to good-way bends with generous radii and stress-relieve formed springs at 200–260 °C.
What is the maximum service temperature of C72500-H06?
C72500-H06 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 C72500-H02 and C72500-O61?
H02 is the default condition — default stocked strip temper: balanced strength and formability for stamped connector shells, lead frames and terminals. O61: pick for deep drawing, severe forming or as the starting stock before customer-side stamping and stress relief. Yield strength is 480 MPa in H02 versus 150 MPa in O61.
Sources
- ASTM B122/B122M — Copper-Nickel-Tin, Copper-Nickel and Copper-Nickel-Zinc Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- EN 1654 / EN 1652 — Copper and copper alloys, strip for springs and connectors (CuNi9Sn2, CW351H) — CEN (2019)
- C72500 alloy datasheet (properties, tempers, machinability rating) — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (copper and copper alloys) — ASM International (2005)
- Cu-Ni-Sn connector strip datasheets (temper strength/hardness tables) — Wieland / Aurubis Stolberg / Materion (2023)
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.