Copper Alloy C71900
UNS C71900
A high-nickel (~32%) copper alloy with chromium addition providing high strength and stress-relaxation resistance, used for springs and electrical connectors requiring elevated-temperature performance.
Reference datasheet — C71900 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the TF00 condition
C71900 tempers and conditions
C71900 is supplied in 8 conditions, soft to hard. TF00 is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Pick for deep forming/stamping of complex parts that will be precipitation hardened after shaping. | 200 | 480 | 40 | 130 HB | 4 % IACS |
Solution heat treated and cold worked, quarter hard | Light cold work for parts needing moderate stiffness with residual bend formability before aging. | 400 | 560 | 20 | 160 HB | 4 % IACS |
Solution heat treated and cold worked, half hard | Mid-strength cold-rolled strip/rod for parts that will be aged to final spring properties. | 500 | 620 | 12 | 190 HB | 4 % IACS |
TF00Default Solution heat treated and precipitation hardened | Standard supply condition: best balance of high strength, ductility and stress-relaxation resistance for springs and connectors. | 550 | 760 | 15 | 24 HRC | 5.5 % IACS |
Solution heat treated and cold worked, full hard | Fully cold-worked strip/wire where maximum as-rolled strength is needed prior to precipitation hardening. | 620 | 700 | 6 | 20 HRC | 4 % IACS |
TD01 and precipitation hardened | Use where aged strength must rise above TF00 but some bend formability is still required. | 720 | 830 | 10 | 27 HRC | 5.8 % IACS |
TD02 and precipitation hardened | Common spring-strip condition for connector contacts needing high contact force with modest bending. | 830 | 900 | 6 | 30 HRC | 6 % IACS |
TD04 and precipitation hardened | Maximum-strength condition for flat springs and preloaded contacts formed to generous bend radii only. | 930 | 970 | 3 | 33 HRC | 6 % IACS |
What is C71900?
A high-nickel (~32%) copper alloy with chromium addition providing high strength and stress-relaxation resistance, used for springs and electrical connectors requiring elevated-temperature performance. C71900 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,200°C (2,192 °F). C71900 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 92% of copper alloy grades. Elongation at break is 15% and the elastic modulus is 152 GPa (22 Msi).
What is C71900 used for?
- springs
- electrical connectors
- relay contacts
- high-temperature fasteners
Advantages
- Stiff — 152 GPa (22 Msi), better than 99% of copper alloy grades
- Good corrosion resistance — 78/100, better than 94% of copper alloy grades
- High service temperature — 320°C (608 °F), better than 93% of copper alloy grades
- High strength — 550 MPa (79.8 ksi), better than 92% of copper alloy grades
Limitations
- Low electrical conductivity — 5.5 % IACS, worse than 95% of copper alloy grades
- Poor heat conductor — 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 90% of copper alloy grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 89% of copper alloy grades
C71900 properties
Typical room-temperature values for C71900-TF00; bars are the position among copper alloy grades.
Physical3
C71900 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,200°C (2,192 °F).
Mechanical14
C71900 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 92% of copper alloy grades. Elongation at break is 15% and the elastic modulus is 152 GPa (22 Msi).
Thermal6
C71900 is rated for continuous service to 320°C (608 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 90% of copper alloy grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
C71900 conducts electricity at 5.5 % IACS, worse than 95% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), better than 94% of copper alloy grades.
Sustainability4
Producing a kilogram of C71900 takes about 75 MJ of energy and emits 5.5 kg of CO₂ — more than 88% of copper alloy grades. Typical recycled content is 25%.
Manufacturability7
C71900's machinability is poor (28/100, worse than 78% of copper alloy grades); weldability good (55/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the copper alloy family
Yield strength against density for every copper alloy grade FabDigit runs. C71900 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C71900
Is C71900 easy to machine?
Gummy, work-hardening Cu-Ni: use sharp positive-rake carbide, rigid setups, heavy constant feed and flood coolant; rate ~20% of free-cutting brass and lower again after aging.
Can C71900 be welded?
GTAW/GMAW with Cu-Ni (ERCuNi) or matching filler is possible, but the HAZ loses the aged condition — re-solution treat and re-age for full strength.
Can C71900 be formed, bent or molded?
Form, stamp and coin in the solution-treated TB00 condition, then precipitation harden; aged tempers need generous bend radii (≥2t transverse) to avoid cracking.
C71900 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 |
|---|---|---|
| Niincludes Co | 28 – 33 | 30 |
| Crprecipitation-hardening element | 2.2 – 3 | 2.6 |
| Fe | ≤ 0.5 | 0.2 |
| Mn | 0.2 – 1 | 0.5 |
| Si | ≤ 0.15 | 0.05 |
| Tigrain/precipitate control | ≤ 0.2 | 0.1 |
| Zrgrain refiner | ≤ 0.2 | 0.12 |
| Zn | ≤ 0.05 | |
| Pb | ≤ 0.02 | |
| C | ≤ 0.1 | 0.04 |
| Curemainder, approx. 65–68% | balance |
What surface finishes work on C71900?
Not anodizable; takes a bright mechanical or electropolish and accepts Ni/Au or Sn electroplating for connector contact surfaces.
Surface treatments FabDigit runs on copper alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
How much does C71900 cost?
C71900 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C71900 — frequently asked
What is C71900 used for?
C71900 is typically used for springs, electrical connectors, relay contacts and high-temperature fasteners. In short: strongest wrought cupronickel; age-hardening spring alloy; holds load to 320 °C.
What is the yield strength of C71900?
C71900 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 92% of copper alloy grades. Strength varies by condition: see the 8 listed tempers.
Is C71900 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 78% of copper alloy grades). Gummy, work-hardening Cu-Ni: use sharp positive-rake carbide, rigid setups, heavy constant feed and flood coolant; rate ~20% of free-cutting brass and lower again after aging.
Can C71900 be welded?
Yes — weldability is rated good (55/100). GTAW/GMAW with Cu-Ni (ERCuNi) or matching filler is possible, but the HAZ loses the aged condition — re-solution treat and re-age for full strength.
What surface finishes work on C71900?
Not anodizable; takes a bright mechanical or electropolish and accepts Ni/Au or Sn electroplating for connector contact surfaces.
Can C71900 be formed, bent or molded?
Form, stamp and coin in the solution-treated TB00 condition, then precipitation harden; aged tempers need generous bend radii (≥2t transverse) to avoid cracking.
What is the maximum service temperature of C71900?
C71900 is rated for continuous use to about 320°C (608 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C71900-TF00 and C71900-TH04?
TF00 is the default condition — standard supply condition: best balance of high strength, ductility and stress-relaxation resistance for springs and connectors. TH04: maximum-strength condition for flat springs and preloaded contacts formed to generous bend radii only. Yield strength is 550 MPa in TF00 versus 930 MPa in TH04.
How much does C71900 cost?
C71900 is a high-cost copper alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Copper Alloy C71900 alloy data (UNS listing) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Specialty Handbook: Copper and Copper Alloys — ASM International (2001)
- ASTM B846 — Standard Terminology for Copper and Copper Alloys (temper designations) — ASTM (2020)
- Copper-nickel alloys for seawater service — technical guidance — Nickel Institute / CDA UK (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.