Copper Alloy C70260-TM04
Precip hard
UNS C70260 · EN CW111C, CuNi2Si
TM04 = mill hardened, full hard
Top mill-hardened level for maximum spring force and relaxation resistance in shallow-formed parts.
Values for the TM04 condition
Other C70260 tempers and conditions
C70260 is listed in 5 conditions; see the grade overview at C70260.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Mill hardened | Pick when deep forming, tight bends or complex stamping dominate and moderate spring force is enough. | 400 | 490 | 15 | 79 HRB | 53 % IACS |
Mill hardened, low-intermediate strength | Use for stamped contacts needing better spring force than TM00 while keeping generous bend radii. | 480 | 550 | 12 | 85 HRB | 51 % IACS |
TM02Default Mill hardened, half hard | The default stocked strip temper: balanced spring force, formability and ~50% IACS conductivity. | 535 | 595 | 9 | 89 HRB | 50 % IACS |
Mill hardened, high strength | Choose for higher contact normal force and better stress relaxation, accepting larger minimum bend radii. | 580 | 630 | 7 | 93 HRB | 48 % IACS |
TM04This page Mill hardened, full hard | Top mill-hardened level for maximum spring force and relaxation resistance in shallow-formed parts. | 620 | 665 | 5 | 96 HRB | 46 % IACS |
What is C70260-TM04?
C70260-TM04 is C70260 in the TM04 condition — top mill-hardened level for maximum spring force and relaxation resistance in shallow-formed parts. C70260-TM04 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 665 MPa (96.5 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 130 GPa (18.9 Msi). C70260-TM04 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,085°C (1,985 °F). TM02 is the default condition FabDigit quotes; TM04 is available on request or by drawing note.
Advantages
- High strength — 620 MPa (89.9 ksi), better than 95% of copper alloy grades
- Stiff — 130 GPa (18.9 Msi), better than 89% of copper alloy grades
- High electrical conductivity — 46 % IACS, better than 78% of copper alloy grades
Limitations
- Limited ductility — 5%, worse than 93% of copper alloy grades
C70260-TM04 properties
Typical room-temperature values for C70260-TM04; 13 are specific to this condition. Other listed values are C70260 reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
C70260-TM04 has a density of 8.83 g/cm³ (0.319 lb/in³), heavier than 65% of copper alloy grades. It melts at 1,085°C (1,985 °F).
Mechanical12
C70260-TM04 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 665 MPa (96.5 ksi) — stronger than 95% of copper alloy grades. Elongation at break is 5% and the elastic modulus is 130 GPa (18.9 Msi).
Thermal6
C70260-TM04 is rated for continuous service to 200°C (392 °F). It conducts heat at 176 W/m·K (101.7 BTU/hr·ft·°F), better than 74% of copper alloy grades. Thermal expansion is 17.6 µm/m·K (9.78 µin/in·°F).
Electrical3
C70260-TM04 conducts electricity at 46 % IACS, better than 78% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 57% of copper alloy grades.
Sustainability4
Producing a kilogram of C70260-TM04 takes about 60 MJ of energy and emits 4 kg of CO₂ — more than 69% of copper alloy grades. Typical recycled content is 35%.
Manufacturability7
C70260-TM04's machinability is fair (42/100, better than 59% of copper alloy grades); weldability fair (45/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C70260-TM04
Is C70260 easy to machine?
Machines like a medium-hard bronze — chips are gummy; use sharp carbide, positive rake and generous coolant; rating ≈30 % of AISI 1212.
Can C70260 be welded?
Resistance and laser welding are practical; fusion welding locally over-ages the strip and loses spring temper, so avoid on formed contacts.
Can C70260 be formed, bent or molded?
Mill-hardened strip stamps and bends well in TM00–TM02 (good-way bends near 0–1t); step up bend radii and prefer good-way orientation at TM03/TM04.
What surface finishes work on C70260?
Not anodizable; standard finishes are Sn, Sn-Pb-free reflow, Ni underplate with Au or Ag flash for contacts; degrease and micro-etch before plating.
C70260 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 | 1.6 – 2.5 | 2 |
| Si | 0.4 – 0.8 | 0.55 |
| Mgoptional micro-addition for relaxation resistance | ≤ 0.15 | — |
| Fe | ≤ 0.2 | — |
| Zn | ≤ 0.5 | — |
| Mn | ≤ 0.1 | — |
| Pb | ≤ 0.02 | — |
| Others (total) | ≤ 0.3 | — |
| Cu≈96.5 % nominal | balance | — |
C70260-TM04 — frequently asked
What is C70260-TM04 used for?
C70260-TM04 is typically used for connectors, lead frames, switch parts and terminals. In short: balanced conductivity and spring force; formable Cu-Ni-Si strip; lower-alloy C70250 alternative.
What is the yield strength of C70260-TM04?
C70260-TM04 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 665 MPa (96.5 ksi) — stronger than 95% of copper alloy grades. Strength varies by condition: see the 5 listed tempers.
Is C70260-TM04 easy to machine?
Not especially — machinability is rated fair (42/100, better than 59% of copper alloy grades). Machines like a medium-hard bronze — chips are gummy; use sharp carbide, positive rake and generous coolant; rating ≈30 % of AISI 1212.
Can C70260-TM04 be welded?
With care — weldability is rated fair (45/100). Resistance and laser welding are practical; fusion welding locally over-ages the strip and loses spring temper, so avoid on formed contacts.
What surface finishes work on C70260-TM04?
Not anodizable; standard finishes are Sn, Sn-Pb-free reflow, Ni underplate with Au or Ag flash for contacts; degrease and micro-etch before plating.
Can C70260-TM04 be formed, bent or molded?
Mill-hardened strip stamps and bends well in TM00–TM02 (good-way bends near 0–1t); step up bend radii and prefer good-way orientation at TM03/TM04.
What is the maximum service temperature of C70260-TM04?
C70260-TM04 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 C70260-TM02 and C70260-TM00?
TM02 is the default condition — the default stocked strip temper: balanced spring force, formability and ~50% IACS conductivity. TM00: pick when deep forming, tight bends or complex stamping dominate and moderate spring force is enough. Yield strength is 535 MPa in TM02 versus 400 MPa in TM00.
Sources
- EN 1654 / EN 1652 — Copper and copper alloys, strip for springs and connectors (CW111C CuNi2Si) — CEN (2019)
- ASTM B888 — Copper Alloy Strip for Electrical Connectors and Lead Frames — ASTM (2020)
- UNS C70260 alloy data — Copper Development Association (copper.org) (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Cu-Ni-Si mill-hardened connector strip datasheets (TM00–TM04) — Various strip producers (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.