Copper Alloy C73500-H04
Supply condition
UNS C73500
H04 = full hard
Pick for flat springs, contacts and stiff stamped parts needing only gentle forming with the grain.
Values for the H04 condition
Other C73500 tempers and conditions
C73500 is listed in 8 conditions; see the grade overview at C73500.
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 bending of decorative parts before final work-hardening. | 145 | 385 | 40 | 78 HB | 6.5 % IACS |
As hot rolled | Mill hot-rolled plate/bar condition for machined blanks and parts that will be finished after forming. | 160 | 380 | 35 | 85 HB | 6.5 % IACS |
Quarter hard | Pick when moderate stiffness is needed but the part still has to be formed or bent across the grain. | 310 | 430 | 20 | 108 HB | 6.3 % IACS |
H02Default Half hard | The general-purpose stocked temper: good balance of strength, formability and finish for hardware, flatware and instrument parts. | 415 | 480 | 10 | 130 HB | 6.2 % IACS |
H04This page Full hard | Pick for flat springs, contacts and stiff stamped parts needing only gentle forming with the grain. | 525 | 585 | 4 | 160 HB | 6 % IACS |
Extra hard | Pick for high-load springs, snap parts and flat stock where maximum strength matters more than bending. | 570 | 655 | 3 | 180 HB | 6 % IACS |
Spring hard | Spring strip for relay blades, contacts and clips formed only in simple bends along the rolling direction. | 620 | 690 | 2 | 195 HB | 6 % IACS |
Extra spring hard | Maximum-strength strip for thin high-deflection springs; essentially no cross-grain formability. | 660 | 725 | 1.5 | 12 HRC | 6 % IACS |
What is C73500-H04?
C73500-H04 is C73500 supplied in the H04 condition — pick for flat springs, contacts and stiff stamped parts needing only gentle forming with the grain. C73500-H04 has a yield strength of 525 MPa (76.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 91% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 127 GPa (18.4 Msi). C73500-H04 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,080°C (1,976 °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 — 525 MPa (76.1 ksi), better than 91% 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
- Low electrical conductivity — 6 % IACS, worse than 93% of copper alloy grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 91% of copper alloy grades
- Poor heat conductor — 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 89% of copper alloy grades
C73500-H04 properties
Typical room-temperature values for C73500-H04; 13 are specific to this condition. Other listed values are C73500 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C73500-H04 has a density of 8.86 g/cm³ (0.32 lb/in³), heavier than 68% of copper alloy grades. It melts at 1,080°C (1,976 °F).
Mechanical12
C73500-H04 has a yield strength of 525 MPa (76.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 91% of copper alloy grades. Elongation at break is 4% and the elastic modulus is 127 GPa (18.4 Msi).
Thermal6
C73500-H04 is rated for continuous service to 150°C (302 °F). It conducts heat at 33 W/m·K (19.1 BTU/hr·ft·°F), worse than 89% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C73500-H04 conducts electricity at 6 % IACS, worse than 93% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C73500-H04 takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 35%.
Manufacturability8
C73500-H04's machinability is poor (32/100, worse than 57% of copper alloy grades); weldability good (55/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C73500-H04
Is C73500 easy to machine?
Rated only ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake carbide/HSS tools, moderate speed, heavy feed and soluble-oil coolant, and avoid dwelling.
Can C73500 be welded?
Solders and brazes very well and resistance/spot welds acceptably; gas welding is not recommended because of zinc loss, and TIG requires low heat input plus post-weld stress relief.
Can C73500 be formed, bent or molded?
Excellent cold formability in O61/H01 (deep drawing, spinning, stamping); interanneal at 600–750 °C and stress-relieve hard tempers at ~250–300 °C to avoid ammonia stress-corrosion cracking.
What surface finishes work on C73500?
Takes a bright silver-white polish and buffs easily; commonly lacquered, oxidised/antiqued, or nickel-, chrome- or silver-plated. Not anodizable.
C73500 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 |
|---|---|---|
| Cu | 70.5 – 73.5 | 72 |
| NiNi + Co | 16.5 – 19.5 | 18 |
| Mn | ≤ 0.5 | — |
| Fe | ≤ 0.25 | — |
| Pb | ≤ 0.1 | — |
| Znremainder, ~7–13 % | balance | — |
C73500-H04 — frequently asked
What is C73500-H04 used for?
C73500-H04 is typically used for flatware, hardware fittings, optical/instrument parts and zippers. In short: spring-temper nickel silver; bright silver-white finish; low machinability, good formability.
What is the yield strength of C73500-H04?
C73500-H04 has a typical yield strength of 525 MPa (76.1 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 91% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C73500-H04 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 57% of copper alloy grades). Rated only ~20 % of free-cutting brass — gummy, work-hardening chips; use sharp positive-rake carbide/HSS tools, moderate speed, heavy feed and soluble-oil coolant, and avoid dwelling.
Can C73500-H04 be welded?
Yes — weldability is rated good (55/100). Solders and brazes very well and resistance/spot welds acceptably; gas welding is not recommended because of zinc loss, and TIG requires low heat input plus post-weld stress relief.
What surface finishes work on C73500-H04?
Takes a bright silver-white polish and buffs easily; commonly lacquered, oxidised/antiqued, or nickel-, chrome- or silver-plated. Not anodizable.
Can C73500-H04 be formed, bent or molded?
Excellent cold formability in O61/H01 (deep drawing, spinning, stamping); interanneal at 600–750 °C and stress-relieve hard tempers at ~250–300 °C to avoid ammonia stress-corrosion cracking.
What is the maximum service temperature of C73500-H04?
C73500-H04 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 C73500-H02 and C73500-O61?
H02 is the default condition — the general-purpose stocked temper: good balance of strength, formability and finish for hardware, flatware and instrument parts. O61: pick for deep drawing, spinning and severe bending of decorative parts before final work-hardening. Yield strength is 415 MPa in H02 versus 145 MPa in O61.
Sources
- ASTM B122/B122M — Copper-Nickel-Tin, Copper-Nickel-Zinc (Nickel Silver) Plate, Sheet, Strip and Rolled Bar — ASTM International (2021)
- ASTM B151/B151M — Copper-Nickel-Zinc and Copper-Nickel Rod and Bar — ASTM International (2021)
- CDA Alloy Database — C73500 Nickel Silver 72-18 — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- GB/T 2040 / GB/T 2059 (BZn18-10 ) — SAC (2017)
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.