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Nickel-Chromium Resistance Alloys

  • Nickel-chromium (NiCr) electric heating alloys are a type of high-resistance heating material primarily composed of nickel (Ni) and chromium (Cr), widely used in electric heating elements. Their key characteristics and performance are as follows:
  • • High resistivity: The resistivity usually ranges from 1.04 to 1.18 μΩ·m (20℃), making it suitable for efficient electric-heat conversion.
  • • High operating temperature: The maximum operating temperature can reach 1100–1250℃ (for instance, Cr20Ni80 can reach 1200℃, and some optimized grades can reach 1250℃).
  • • Excellent oxidation resistance: Forms a dense Cr₂O₃ oxide layer on the surface, effectively preventing further oxidation.
  • • Good high-temperature strength and plasticity: Resistant to deformation at high temperatures, not prone to embrittlement after long-term use, facilitating maintenance and reprocessing.
  • • Non-magnetic: Suitable for low-temperature or precision equipment sensitive to magnetic fields.
  • • Low temperature coefficient of resistance: Ensures that the resistance remains relatively stable with temperature changes, suitable for precise temperature control applications.• Low temperature coefficient of resistance: Ensures that the resistance remains relatively stable with temperature changes, suitable for precise temperature control applications.
  • • Good machinability and weldability: Can be drawn into wires, rolled into strips, and supports various connection methods such as arc welding and gas welding.
  • Advantages and disadvantages compared with other heating alloys:
  • • Superior to iron-chromium-aluminum (FeCrAl):
  • o Higher high-temperature strength and creep resistance;
  • o Retains plasticity after long-term use and is less prone to brittle fracture;
  • o Non-magnetic (FeCrAl is magnetic below >600℃);
  • o Better corrosion resistance (except in sulfur-containing atmospheres).
  • • Inferior to iron-chromium-aluminum:
  • o Higher cost (due to nickel content);
  • o Slightly lower resistivity;
  • o Susceptible to corrosion in sulfur-containing reducing atmospheres. NiCr alloy working temp and resistivity chart
  • Typical applications:
  • • Household appliances: Heating elements for electric ovens, kettles, fan heaters, etc.;
  • • Industrial electric furnaces: Resistance wires, heating tubes, heat treatment furnaces;
  • • Aerospace: Gas turbine blades, high-temperature sensors;
  • • Chemical equipment: Heat-resistant components for reactors and heat exchangers;
  • • Vacuum coating: As NiCr targets for magnetron sputtering.
Cr20Ni80 wires
NiCr8020 resistance wire
Cr30Ni70 wires
Main Properties and Characteristics of Nickel-Chromium and Nickel-Chromium-Iron Material

(Swipe the screen to view the full table)

Alloy Name

Properties
 Cr20Ni80 Cr30Ni70 Cr15Ni60 Cr20Ni35 Cr20Ni30
Main
Chemical
Components		 Ni Remainder Remainder 55.0-61.0 34.0-37.0 30.0-34.0
Cr 20.0-23.0 28.0-31.0 15.0-18.0 18.0-21.0 18.0-21.0
Fe ≤1.0 ≤1.0 Remainder Remainder Remainder
Maximum operating temperature 1200 1250 1150 1100 1100
Resistivity 20ºC (μΩ·m) 1.09±0.05 1.18±0.05 1.12±0.05 1.04±0.05 1.04±0.05
Density(g/cm3) 8.40 8.10 8.20 7.90 7.90
Coefficient of heat conductivity
(20ºC) (W/m·K)		 15 14 13 13 13
Coefficient of linear expansion
(20ºC ~ 1000ºC) (α×10-6/ºC)		 18.0 17.0 17.0 19.0 19.0
Melting point(ºC) 1400 1380 1390 1390 1390
Tensile strength(Rm/MPa) ≥650 ≥650 ≥600 ≥600 ≥600
Elongation after Fracture (A/%) ≥20 ≥20 ≥20 ≥20 ≥20
Accelerated life test(Hours/ºC) ≥80/1200 ≥50/1250 ≥80/1150 ≥80/1100 ≥50/1100
Microscopic structure Austenite Austenite Austenite Austenite Austenite
Magnetism Non-magnetic Non-magnetic Weak magnetic Non-magnetic Non-magnetic
The temperature correction factor for Nickel-Chrome and Nickel-Chrome-Iron alloys

Temp(ºC)

20

100

200

300

400

500

600

700

800

900

1000

1100

1200

Cr20Ni80

1

1.006

1.012

1.018

1.025

1.026

1.018

1.01

1.008

1.01

1.014

1.021

1.025

Cr30Ni70

1

1.007

1.016

1.028

1.038

1.044

1.036

1.03

1.028

1.029

1.033

1.037

1.043

Cr15Ni60

1

1.011

1.024

1.038

1.052

1.064

1.069

1.073

1.078

1.088

1.095

1.109

Cr20Ni35

1

1.029

1.061

1.09

1.115

1.139

1.157

1.173

1.188

1.208

1.219

1.228

Cr20Ni30

1

1.023

1.052

1.079

1.103

1.125

1.141

1.158

1.173

1.187

1.201

1.214

1.226
– To obtain resistance at working temperature, multiply by the factor in above table.