Copper Alloy C77100-HR50
Supply condition
UNS C77100
HR50 = cold worked and stress-relieved
Use when cold-worked strength is required but residual-stress SCC (ammonia atmospheres) must be avoided.
Values for the HR50 condition
Other C77100 tempers and conditions
C77100 is listed in 8 conditions; see the grade overview at C77100.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
O60Default Soft annealed | Default stock condition for deep drawing, bending and stamping of blanks before final forming. | 180 | 420 | 40 | 55 HRB | — |
Quarter hard | Light temper when moderate stiffness must be combined with continued bending/forming. | 380 | 500 | 25 | 130 HB | 4.5 % IACS |
Half hard | General-purpose semi-rigid temper for machined and lightly formed precision parts. | 470 | 570 | 15 | 155 HB | 4.5 % IACS |
HR50This page Cold worked and stress-relieved | Use when cold-worked strength is required but residual-stress SCC (ammonia atmospheres) must be avoided. | 500 | 580 | 14 | 7 HRC | 4.5 % IACS |
Full hard | Choose for flat springs, contacts and wear surfaces where only gentle forming is needed. | 570 | 660 | 6 | 10 HRC | 4.4 % IACS |
Extra hard | Higher-strength strip for stamped contacts and stiff clips with minimal bending. | 640 | 720 | 4 | 13 HRC | 4.4 % IACS |
Spring hard | Spring strip for flexures and diaphragms needing high elastic limit and white finish. | 700 | 790 | 3 | 16 HRC | 4.4 % IACS |
Extra spring hard | Maximum-strength cold-rolled temper for thin, highly stressed spring elements. | 760 | 840 | 2 | 18 HRC | 4.4 % IACS |
What is C77100-HR50?
C77100-HR50 is C77100 supplied in the HR50 condition — use when cold-worked strength is required but residual-stress SCC (ammonia atmospheres) must be avoided. C77100-HR50 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 89% of copper alloy grades. Elongation at break is 14% and the elastic modulus is 132 GPa (19.1 Msi). C77100-HR50 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). O60 is the default condition FabDigit quotes; HR50 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 88/100, better than 97% of copper alloy grades
- Stiff — 132 GPa (19.1 Msi), better than 93% of copper alloy grades
- High strength — 500 MPa (72.5 ksi), better than 89% of copper alloy grades
Limitations
- Poor heat conductor — 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 99% of copper alloy grades
- Low electrical conductivity — 4.5 % IACS, worse than 98% of copper alloy grades
- High embodied carbon — 5.8 kg CO₂/kg, worse than 91% of copper alloy grades
C77100-HR50 properties
Typical room-temperature values for C77100-HR50; 22 are specific to this condition. Other listed values are C77100 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C77100-HR50 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).
Mechanical11
C77100-HR50 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 89% of copper alloy grades. Elongation at break is 14% and the elastic modulus is 132 GPa (19.1 Msi).
Thermal6
C77100-HR50 is rated for continuous service to 200°C (392 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 99% of copper alloy grades. Thermal expansion is 16.2 µm/m·K (9 µin/in·°F).
Electrical3
C77100-HR50 conducts electricity at 4.5 % IACS, worse than 98% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 69% of copper alloy grades.
Sustainability4
Producing a kilogram of C77100-HR50 takes about 78 MJ of energy and emits 5.8 kg of CO₂ — more than 90% of copper alloy grades. Typical recycled content is 35%.
Manufacturability6
C77100-HR50's machinability is poor (33/100, worse than 53% of copper alloy grades); weldability fair (50/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C77100-HR50
Is C77100 easy to machine?
Tough and gummy — use sharp, positive-rake carbide or HSS-Co tools, moderate speed with heavy feed and good coolant; rating only ~20 % of free-cutting brass, so specify a leaded nickel silver if screw-machining volumes are high.
Can C77100 be welded?
Best joined by resistance welding, GTAW with matched or Cu-Ni filler, or silver brazing; avoid overheating to limit zinc fuming and keep parts stress-relieved to prevent cracking.
Can C77100 be formed, bent or molded?
Excellent deep-draw and stamping performance in the annealed temper, but it work-hardens fast — plan interanneals around 600–750 °C with rapid cooling.
What surface finishes work on C77100?
Polishes to a bright white, tarnish-resistant surface; readily nickel-, chrome- or silver-plated, and lacquering is used to preserve the as-polished lustre.
C77100 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 |
|---|---|---|
| Nihigh-nickel grade; verify against mill certificate — C77100 limits are less widely published than C77000 | 23 – 27 | 25 |
| Cu | 46 – 50 | 48 |
| Mndeoxidiser | ≤ 0.5 | 0.2 |
| Fe | ≤ 0.25 | — |
| Pb | ≤ 0.05 | — |
| Znremainder, nominally ~27 % | balance | — |
C77100-HR50 — frequently asked
What is C77100-HR50 used for?
C77100-HR50 is typically used for precision instrument parts, optical hardware and high-end fittings. In short: highest-nickel nickel silver; bright white, tarnish resistant; deep-draw formability score 85.
What is the yield strength of C77100-HR50?
C77100-HR50 has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 89% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C77100-HR50 easy to machine?
Not especially — machinability is rated poor (33/100, worse than 53% of copper alloy grades). Tough and gummy — use sharp, positive-rake carbide or HSS-Co tools, moderate speed with heavy feed and good coolant; rating only ~20 % of free-cutting brass, so specify a leaded nickel silver if screw-machining volumes are high.
Can C77100-HR50 be welded?
With care — weldability is rated fair (50/100). Best joined by resistance welding, GTAW with matched or Cu-Ni filler, or silver brazing; avoid overheating to limit zinc fuming and keep parts stress-relieved to prevent cracking.
What surface finishes work on C77100-HR50?
Polishes to a bright white, tarnish-resistant surface; readily nickel-, chrome- or silver-plated, and lacquering is used to preserve the as-polished lustre.
Can C77100-HR50 be formed, bent or molded?
Excellent deep-draw and stamping performance in the annealed temper, but it work-hardens fast — plan interanneals around 600–750 °C with rapid cooling.
What is the maximum service temperature of C77100-HR50?
C77100-HR50 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 C77100-O60 and C77100-H10?
O60 is the default condition — default stock condition for deep drawing, bending and stamping of blanks before final forming. H10: maximum-strength cold-rolled temper for thin, highly stressed spring elements. Yield strength is 180 MPa in O60 versus 760 MPa in H10.
Sources
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- CDA/UNS Copper Alloy Data (C77000-series nickel silvers) — Copper Development Association (2023)
- ASTM B122/B122M — Copper-Nickel-Zinc (Nickel Silver) Plate, Sheet, Strip and Rolled Bar — ASTM International (2022)
- GB/T 2059 / GB/T 2040 — 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.