Constantan Wire 6J40 - Cu55Ni45

Constantan 6J40 (Cu55Ni45) resistance alloy wire, drawn from 0.05 mm to 6.00 mm. Near-zero temperature coefficient of resistance - the standard material for wire-wound and sampling resistors, shunts and power resistors, and the designated negative leg of type E, J and T thermocouples.

Grades & composition

Designation and composition.

GradeNominal compositionChinese standardNearest international reference
6J40
Cu55Ni45		 Cu approx. 55 %, Ni approx. 45 % GB/T 6145-2010 ASTM B267 · IEC 60115 series

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Electrical & dimensional

Supply range and condition.

PropertyValue
Resistivity @ 20 °CConfirmed on the batch inspection report
Temperature coefficient @ 20 °CNear zero. Confirmed per batch against the technical agreement.
Thermal EMF against copperLow; measured per batch
Diameter range0.05 - 6.00 mm
TemperM (soft)
SurfaceBright, clean
Values above are nominal. Composition, resistivity, temperature coefficient of resistance (TCR) and thermal EMF are confirmed by the inspection report issued with each shipment - this page confirms feasibility and range, it is not the inspection certificate.

Typical applications

Where this grade is specified.

  • Precision wire-wound resistors
  • Current-sampling resistors and shunts
  • Power resistors
  • The negative leg of type E, J and T thermocouples

Constantan or manganin? Both are low-TCR resistance alloys. Constantan is chosen by application (thermocouple leg, sampling or wire-wound resistor); manganin is chosen by a precision requirement (lowest TCR, lowest thermal EMF against copper). Do not substitute manganin for a thermocouple negative leg - the reference table will no longer match. Full comparison.

6J40 GB/T 6145-2010 Wire-wound resistors Shunts
Constantan Wire coil
Constantan Wire - supplied in the temper your drawing calls for.

Order facts

What you need before you send a drawing.

Minimum orderSample 100 g at cost · orders from 1 kg · production pricing from 5 kg
Standard lead time3 - 7 days from order confirmation
Temper suppliedM (soft)
Diameter0.05 - 6.00 mm round wire
HS classificationHS 7408 (copper alloy wire)
DocumentsMaterial test certificate standard; third-party test report on request
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Export & compliance

Stated plainly, not oversold.

Export note - nickel-containing material to the United States: assess California Prop 65 (metallic nickel is listed with no safe harbour). To the EU: observe REACH nickel release limits and the General Product Safety Regulation (GPSR), which applies from 2026-06-01 and requires an EU-based responsible person. Bare alloy wire is a raw material, not a finished electrical device, so UL / CSA / CE device marks do not apply to it. Composition, resistivity, TCR and thermal EMF are stated as nominal on this page and are confirmed by the inspection report issued with each shipment.
Related selection notes: Constantan vs manganin · Shunt material choice

Next step

Send the grade, diameter, temper and quantity.

Tell us what the wire has to do and the date your line needs it. We come back with a confirmed lead time, the achievable tolerance and the documents we can issue. Sample 100 g at cost; orders from 1 kg; production pricing from 5 kg.

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