Grade datasheet · 6J40
Constantan Wire (6J40 / Cu55Ni45)
A copper-nickel alloy with a resistivity that barely moves with temperature — roughly 0.49 µΩ·m at room temperature, and a coefficient close to zero. That flatness is why it is used for shunts, sampling resistors and the negative leg of type E, J and T thermocouples.
0.018–6.00Diameter, mm
1 kgMinimum order
3–7 dLead time
MTCWith every lot
Identification
What this grade is called elsewhere
| System | Designation |
|---|---|
| GB / China | 6J40 |
| Common | Constantan / Cu55Ni45 / CuNi44 |
| UNS | N04400 (not applicable) — see CuNi44 |
| W.Nr. | 2.0842 (CuNi44) |
| JIS | CNC1 |
| IEC | Type E / J / T negative leg |
Grade equivalence is indicative. Confirm against the standard your drawing cites; our quotation states the designation we will produce to.
Composition
Nominal chemistry, % by weight
| Element | Nominal / limit |
|---|---|
| Ni | ≈ 45 |
| Mn | ≤ 0.50 |
| Cu | Balance |
| Fe | ≤ 0.50 |
| C | ≤ 0.10 |
Properties
What the numbers are, and where they stop
| Property | Value |
|---|---|
| Electrical resistivity, 20 °C | ≈ 0.49 µΩ·m |
| Temperature coefficient (20–100 °C) | ≈ ±20 ppm/K |
| Density | 8.90 g/cm³ |
| Melting range | ≈ 1210–1260 °C |
| Max service in air | ≈ 400 °C |
| Tensile, soft | ≈ 400–520 MPa |
| Elongation, soft | ≥ 25 % |
Nominal values for selection only. Contractual composition, tolerance and mechanical properties are stated on the inspection report issued with each shipment.
Use
Where this grade earns its place
- Shunt and current-sampling resistors
- Precision wire-wound resistors
- Negative leg of type E / J / T thermocouples
- Compensating leads
Family: Constantan Wire
Questions we get asked
Constantan or manganin for a shunt?
Constantan for higher resistivity and better workability at moderate accuracy; manganin where the lowest possible temperature coefficient of resistance is the deciding factor. Most shunts are constantan because it is cheaper and easier to solder.
Can you match constantan legs to the positive leg?
Yes. For type E, J and T we draw the negative leg from the same melt as the order and supply the pair together.
What diameters are available below 0.10 mm?
0.05 mm is routine. 0.025 mm and finer are drawn on request — this is the range where our fine-wire lines are concentrated.
Send the specification — diameter, grade, temper, quantity.
We come back with a confirmed lead time and the documentation we can issue for the shipment. 100 g sample at cost; orders from 1 kg.
Request a quotation Order a 100 g sample