Copper Alloy C70250
UNS C70250 · ASTM B740 · EN CW112C, CuNi3Si1Mg
C70250 is a precipitation-hardened copper–nickel–silicon–magnesium alloy (CuNi3Si1Mg, also listed as B740 and CW112C) that reaches beryllium-copper-like strength and formability without beryllium.
Reference datasheet — C70250 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 TM02 condition
C70250 tempers and conditions
C70250 is supplied in 15 conditions, soft to hard. TM02 is the default FabDigit quotes; the values on this page are for it.
Compare all 15 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated | Choose for severe forming or deep drawing, then age (TF00) to develop strength. | 170 | 380 | 35 | 55 HRB | 22 % IACS |
Solution heat treated and cold worked, full hard | Intermediate mill condition supplied when the customer performs its own ageing after stamping. | 520 | 570 | 6 | 157 HB | 24 % IACS |
Mill hardened | Use where the part is severely formed after stamping and no post-forming heat treatment is possible. | 530 | 600 | 13 | 88 HRB | 40 % IACS |
TD01 and precipitation hardened | Lowest-strength aged temper when tight 90° bends in the bad-way direction are required. | 550 | 620 | 12 | 171 HB | 38 % IACS |
Mill hardened | Small strength step above TM00 for contacts with moderately tight bad-way bends. | 600 | 655 | 11 | 176 HB | 40 % IACS |
TD02 and precipitation hardened | Balanced aged temper for stamped contacts needing moderate bending plus high spring force. | 630 | 690 | 9 | 188 HB | 38 % IACS |
TM02Default Mill hardened, half hard | The default stocked strip temper: best all-round mix of ~690 MPa strength, 40 % IACS and formability. | 640 | 700 | 9 | 200 HV | 40 % IACS |
Rolled and order-strengthened | Cold-rolled strip given a low-temperature strengthening/stress-relief anneal for flat, low-springback coil stock. | 645 | 690 | 7 | 188 HB | 38 % IACS |
Mill hardened, higher strength | Choose for higher contact normal force and better stress-relaxation resistance with modest forming. | 685 | 740 | 8 | 210 HV | 39 % IACS |
Cold rolled (H03) and precipitation heat treated | Pick when the highest aged spring strength is needed and only generous bend radii are used. | 710 | 760 | 6 | 205 HB | 37 % IACS |
Mill hardened, full hard | For miniature contacts needing maximum spring force with only gentle forming. | 720 | 775 | 6 | 18 HRC | 39 % IACS |
Rolled and order-strengthened, hard | Harder rolled-and-strengthened level for stamped parts requiring high yield with minimal forming. | 730 | 775 | 5 | 209 HB | 37 % IACS |
Mill hardened, extra hard | Extra-high-strength mill-hardened strip for flat springs formed in the good-way direction only. | 755 | 810 | 5 | 20 HRC | 38 % IACS |
TD04 and precipitation hardened | Maximum-strength aged strip for flat springs and contacts formed with large radii only. | 760 | 800 | 4 | 20 HRC | 36 % IACS |
Mill hardened, spring hard | Top mill-hardened level; use for flat, essentially unformed spring elements at maximum load. | 800 | 845 | 4 | 22 HRC | 37 % IACS |
What is C70250?
C70250 is a precipitation-hardened copper–nickel–silicon–magnesium alloy (CuNi3Si1Mg, also listed as B740 and CW112C) that reaches beryllium-copper-like strength and formability without beryllium. Mill-hardened strip in the TM and TH tempers gives 640 MPa yield, 700 MPa tensile, 9 % elongation and 40 % IACS conductivity, which is why it is widely specified for high-reliability stamped connectors and springs. Maximum service temperature is about 200 °C, thermal conductivity is 155 W/m·K, and the alloy is not suited to fusion welding; C17410 is the usual alternative when higher conductivity is required. C70250 has a density of 8.82 g/cm³ (0.319 lb/in³), heavier than 63% of copper alloy grades. It melts at 1,065°C (1,949 °F). C70250 has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 9% and the elastic modulus is 131 GPa (19 Msi).
What is C70250 used for?
- Automotive connectors
- Consumer electronics connectors
- Precision springs
- EMI shielding fingers
Advantages
- High strength — 640 MPa (92.8 ksi), better than 95% of copper alloy grades
- Stiff — 131 GPa (19 Msi), better than 91% of copper alloy grades
- Forms and bends easily — 65/100, better than 78% of copper alloy grades
Limitations
- Limited ductility — 9%, worse than 79% of copper alloy grades
C70250 properties
Typical room-temperature values for C70250-TM02; bars are the position among copper alloy grades.
Physical3
C70250 has a density of 8.82 g/cm³ (0.319 lb/in³), heavier than 63% of copper alloy grades. It melts at 1,065°C (1,949 °F).
Mechanical11
C70250 has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 9% and the elastic modulus is 131 GPa (19 Msi).
Thermal6
C70250 is rated for continuous service to 200°C (392 °F). It conducts heat at 155 W/m·K (89.6 BTU/hr·ft·°F), better than 73% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C70250 conducts electricity at 40 % IACS, better than 74% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C70250 takes about 58 MJ of energy and emits 4 kg of CO₂ — more than 61% of copper alloy grades. Typical recycled content is 30%.
Manufacturability7
C70250's machinability is fair (35/100, better than 51% of copper alloy grades); weldability fair (35/100); formability good (65/100).
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. C70250 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C70250
Is C70250 easy to machine?
Machines like a hard bronze — moderate rating (~30 % of AISI 1212); use sharp carbide, positive rake, high speed and flood coolant; stamping dies wear faster than with brass so carbide tooling is preferred.
Can C70250 be welded?
Not suited to fusion welding (hot-crack sensitive, ageing lost in HAZ); resistance/spot welding, laser microwelding and soldering/brazing are the practical joining routes.
Can C70250 be formed, bent or molded?
Form in TM/TH tempers with grain-direction-aware bend radii (good-way ≈0–1t, bad-way 1–3t depending on temper); for severe draws start from TB00 and age at ~450–480 °C afterwards.
C70250 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 |
|---|---|---|
| Ni | 2.2 – 4.2 | 3 |
| Si | 0.25 – 1.2 | 0.65 |
| Mg | 0.05 – 0.3 | 0.15 |
| Zn | ≤ 1 | |
| Fe | ≤ 0.2 | |
| Mn | ≤ 0.1 | |
| Pb | ≤ 0.05 | |
| CuCu + named elements 99.5 % min | balance |
What surface finishes work on C70250?
Readily electroplated with Sn, Ni, Ag or Au and easily soldered; no anodizing — protect with plating or antitarnish rinse to prevent oxide/tarnish on 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).
Equivalent designations
Standards and trade names that resolve to Copper Alloy C70250 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- B740
- EN / DIN / Werkstoff-Nr.
- CW112CCuNi3Si1Mg
How much does C70250 cost?
C70250 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.
C70250 — frequently asked
What is C70250 used for?
C70250 is typically used for automotive connectors, consumer electronics connectors, precision springs and EMI shielding fingers. In short: beryllium-free connector alloy; strength with 40 % IACS; mill-hardened strip tempers.
What is the yield strength of C70250?
C70250 has a typical yield strength of 640 MPa (92.8 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 95% of copper alloy grades. Strength varies by condition: see the 15 listed tempers.
Is C70250 easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of copper alloy grades). Machines like a hard bronze — moderate rating (~30 % of AISI 1212); use sharp carbide, positive rake, high speed and flood coolant; stamping dies wear faster than with brass so carbide tooling is preferred.
Can C70250 be welded?
With care — weldability is rated fair (35/100). Not suited to fusion welding (hot-crack sensitive, ageing lost in HAZ); resistance/spot welding, laser microwelding and soldering/brazing are the practical joining routes.
What surface finishes work on C70250?
Readily electroplated with Sn, Ni, Ag or Au and easily soldered; no anodizing — protect with plating or antitarnish rinse to prevent oxide/tarnish on contact surfaces.
Can C70250 be formed, bent or molded?
Form in TM/TH tempers with grain-direction-aware bend radii (good-way ≈0–1t, bad-way 1–3t depending on temper); for severe draws start from TB00 and age at ~450–480 °C afterwards.
What is the maximum service temperature of C70250?
C70250 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 C70250-TM02 and C70250-TB00?
TM02 is the default condition — the default stocked strip temper: best all-round mix of ~690 MPa strength, 40 % IACS and formability. TB00: choose for severe forming or deep drawing, then age (TF00) to develop strength. Yield strength is 640 MPa in TM02 versus 170 MPa in TB00.
How much does C70250 cost?
C70250 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
- ASTM B740 — Copper-Nickel-Tin/Copper-Nickel-Silicon Strip for Electrical Connectors — ASTM International (2020)
- ASTM B601 — Temper Designations for Copper and Copper Alloys — ASTM International (2019)
- CDA Alloy Database — C70250 — Copper Development Association (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- High-performance Cu-Ni-Si connector strip datasheets (Wieland/Olin-type C7025) — producer (2022)
- EN 1654 / CW112C CuNi3Si1Mg strip for springs and connectors — CEN (2019)
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.