Content:
Types of Nikrothal® alloys
Advantages of Nikrothal® alloys
Physical and mechanical properties
Summary
Product varieties
Types of Nikrothal® alloys
Nikrothal® 80: Up to 1,200°C (2,190°F)
It is a premium-quality alloy known for its high nickel content, which provides excellent workability and high-temperature strength.
Nikrothal® 80 is widely used in demanding applications within the electric appliance industry, particularly for tubular element applications.
Nikrothal® 60: Up to 1,150°C (2,100°F)
It is suitable for a range of domestic and furnace applications and offers good corrosion resistance, excellent oxidation properties, and superior form stability, making it reliable for high-temperature use.
However, its corrosion resistance may be reduced in sulfur-containing atmospheres.
Typical applications for Nikrothal® 60 include use as suspended coils, where it is most commonly utilized, and less frequently in tubular heating elements.
Nikrothal® 40: Up to1,100°C (2,010°F)
The primary advantage of this alloy is its lower cost due to its reduced nickel content.
It is suitable for use in a variety of domestic appliances and general heating equipment where moderate temperatures are required.
Nikrothal® 70: Up to 1,250°C (2,280°F)
Typical applications for Nikrothal® 70 include use as electrical heating elements in industrial furnaces.
This alloy is particularly well-suited for use in reducing atmospheres, as it is resistant to “green rot,” a type of corrosion that affects some alloys in such environments.
Advantages of Nikrothal® alloys
Higher hot and creep strength
Nikrothal® alloys exhibit higher hot and creep strength compared to Kanthal® alloys. Although Kanthal® APM and Kanthal® AF have good form stability and are superior to other Kanthal® grades, they do not match the hot and creep strength of Nikrothal® alloys.
Better ductility after use
Nikrothal® alloys maintain their ductility even after prolonged use, ensuring flexibility and durability over time.
Higher emissivity
Fully oxidized Nikrothal® alloys have a higher emissivity than Kanthal® alloys. This means that at the same surface load, Nikrothal® alloys operate at a somewhat lower element temperature, enhancing efficiency in certain applications.
Non-magnetic properties
Nikrothal® alloys are generally non-magnetic, making them advantageous for low-temperature applications where non-magnetic materials are required. The exception to this is Nikrothal® 60, which is magnetic at low temperatures. In contrast, Kanthal® alloys become non-magnetic only when heated above 600°C (1,100°F).
Better wet corrosion resistance
Nikrothal® alloys generally offer better corrosion resistance at room temperature than non-oxidized Kanthal® alloys, except in environments containing sulfur or certain controlled atmospheres.
Physical and mechanical properties
Nikrothal® 80 | Nikrothal® Te | Nikrothal® 70 | Nikrothal® 60 | Nikrothal® 40 | ||
---|---|---|---|---|---|---|
Max continuous operating temp. |
°C |
1,200 |
1,200 |
1,250 |
1,150 |
1,100 |
Nominal composition (See Note), % |
Cr |
20 – – 80 |
22 – 9 balance |
30 – – 70 |
16 – balance 60 |
20 – balance 35 |
Density ρ |
g/cm3 |
8.30 (0.300) |
8.10 (0.293) |
8.10 (0.293) |
8.20 (0.296) |
7.90 (0.285) |
Resistivity at 20°C at 68°F |
Ω mm2/m Ω/cmf |
1.09 (655) |
1.19 (716) |
1.18 (709) |
1.11 (668) |
1.04 (626) |
Temperature factor of the resistivity, Ct 250°C (480°F) 500°C (930°F) 800°C (1,470°F) 1,000°C (1,830°F) 1,200°C (2,190°F) |
1.02 1.05 1.04 1.05 1.07 |
1.04 1.06 1.06 1.07 1.07 |
1.02 1.05 1.04 1.05 1.06 |
1.04 1.08 1.10 1.11 – |
1.08 1.15 1.21 1.23 – |
|
Linear thermal expansion coefficient α, × 10-6/K 20 – 100°C (68 – 210°F) 20 – 250°C (68 – 480°F) 20 – 500°C (68 – 930°F) 20 – 750°C (68 – 1,380°F) 20 – 1,000°C (68 – 1,840°F) |
– 15 16 17 18 |
– 14 15 16 17 |
– 14 15 16 17 |
– 16 17 18 18 |
– 16 17 18 19 |
|
Thermal conductivity λ at 50°C at 122°F |
W/m K (Btu in/ft2 h °F) |
15 (104) |
14 (97) |
14 (97) |
14 (97) |
13 (90) |
Specific heat capacity at 20°C at 68°F |
kJ/kg K (Btu/lb °F) |
0.46 (0.110) |
0.46 (0.110) |
0.46 (0.110) |
0.46 (0.110) |
0.50 (0.119) |
Melting point (approx.) | °C (°F) |
1,400 (2,550) |
1,380 (2,515) |
1,380 (2,515) |
1,390 (2,535) |
1,390 (2,535) |
Mechanical properties* (approx.) |
||||||
Tensile strength | N/mm2 (psi) |
810 (117,500) |
800 (116,000) |
820 (118,900) |
730 (105,900) |
675 (97,900) |
Yield point | N/mm2 (psi) |
420 (60,900) |
390 (56,600) |
430 (62,400) |
370 (53,700) |
340 (49,300) |
Hardness | Hv | 180 | 190 | 185 | 180 | 180 |
Elongation at rupture | % | 30 | 30 | 30 | 35 | 35 |
Tensile strength at 900°C | N/mm2 (psi) |
100 (14,500) |
– – |
120 (17,400) |
100 (14,500) |
120 (17,400) |
Creep strength*** |
N/mm2 (psi) N/mm2 (psi) N/mm2 (psi) N/mm2 (psi) |
15 (2,160) 4 (560) – – – – |
15 (2,160) 4 (560) – – – – |
– – – – – – – – |
15 (2,160) 4 (560) – – – – |
20 (2,900) 4 (560) – – – – |
Magnetic properties | 2) | 2) | 2) | 3) | 2) | |
Emissivity, fully oxidized condition | 0.88 | 0.88 | 0.88 | 0.88 | 0.88 | 0.88 |
Note: Composition listed is nominal. Actual composition may vary to meet standard electrical resistance and dimensional tolerances.
* The values given apply for sizes of approx. 1.0 mm diameter (0.039 in)
** 4.0 mm (0.157 in) Thinner gauges have higher strength and hardness values while the corresponding values are lower for thicker gauge
*** Calculated from observed elongation in a Kanthal standard furnace test. 1% elongation after 1,000 hours
1) Magnetic (Curie point approx. 600°C (1,100°F)) 2) Non-magnetic 3) Slightly magnetic
Summary
Nikrothal® alloys are designed for high temperatures: for creep strength and ductility.
Maximum operating temperature per alloy
Resistivity vs.temperature
Product varieties
Kanthal® and Nikrothal® alloys are available in specialized forms such as wire, strips (0.10–3.5 mm thick, 4–195 mm wide), rods, and straightened wire. These versatile forms ensure adaptability for high-temperature and resistance needs.
Rod | Wire | Strip |
Straightned wire |
|
Nikrothal® 80 | • | • | • | |
Nikrothal® 70 | • | • | • | |
Nikrothal® 60 | • | • | • | |
Nikrothal® 40 | • | • | • | • |