Kanthal® AF is a ferritic iron-chromium-aluminium alloy (FeCrAl alloy) for use at temperatures up to 1300°C (2370°F). The alloy is characterized by excellent oxidation resistance and very good form stability resulting in long element life.
Kanthal® AF is typically used in electrical heating elements in industrial furnaces and home appliances.
Example of applications in the appliance industry are in open mica elements for toasters, hair dryers, in meander shaped elements for fan heaters and as open coil elements on fibre insulating material in ceramic glass top heaters in ranges, in ceramic heaters for boiling plates, coils on molded ceramic fibre for cooking plates with ceramic hobs, in suspended coil elements for fan heaters, in suspended straight wire elements for radiators, convection heaters, in porcupine elements for hot air guns, radiators, tumble dryers.
Chemical composition
| | C % | Si % | Mn % | Cr % | Al % | Fe % |
|---|
| †Nominal composition |
|
|
|
|
5.3 |
Bal. |
|---|
| Min |
- |
- |
- |
20.5 |
- |
|
|---|
| Max |
0.08 |
0.7 |
0.4 |
23.5 |
- |
|
|---|
†
Mechanical properties
| Wire size |
Yield strength |
Tensile strength |
Elongation |
Hardness |
| Ø |
Rp0.2 |
Rm |
A |
|
| mm (in) |
MPa (ksi) |
MPa (ksi) |
% |
Hv |
| 1.0 (0.04) |
500 (73) |
700 (102) |
23 |
230 |
| 4.0 (0.16) |
475 (69) |
680 (99) |
18 |
230 |
Mechanical properties at elevated temperature
| Temperature °C |
900 |
1000 |
1100 |
1200 |
1300 |
| Temperature °F |
1652 |
1832 |
2012 |
2192 |
2372 |
| MPa |
37 |
20 |
12 |
6 |
4 |
| ksi |
5.4 |
2.9 |
1.7 |
0.9 |
0.6 |
Ultimate tensile strength - deformation rate 6.2 x 10-2 /min
Creep strength - 1% elongation in 1000 h
| Temperature °C |
1100 |
1200 |
| Temperature °F |
2012 |
2192 |
| MPa |
0.7 |
0.3 |
| psi |
100 |
44 |
Physical properties
| Density g/cm3 (lb/in3) |
7.15 (0.258) |
| Electrical resistivity at 20°C Ω mm2/m (Ω circ. mil/ft) |
1.39 (836) |
| Poisson's ratio |
0.30 |
Young's modulus
| Temperature °C |
20 |
100 |
200 |
400 |
600 |
800 |
1000 |
| Temperature °F |
68 |
212 |
392 |
752 |
1112 |
1472 |
1832 |
| GPa |
220 |
210 |
205 |
190 |
170 |
150 |
130 |
| Msi |
32 |
30 |
30 |
28 |
25 |
22 |
19 |
Temperature factor of resistivity
| Temperature °C |
100 |
200 |
300 |
400 |
500 |
600 |
700 |
800 |
900 |
1000 |
1100 |
1200 |
1300 |
| Temperature °F |
212 |
392 |
572 |
752 |
932 |
1112 |
1292 |
1472 |
1652 |
1832 |
2012 |
2192 |
2372 |
| Ct |
1.00 |
1.01 |
1.01 |
1.02 |
1.03 |
1.04 |
1.04 |
1.05 |
1.05 |
1.06 |
1.06 |
1.06 |
1.06 |
Coefficient of thermal expansion
| Temperature °C (°F) |
Thermal Expansion x 10-6/K (10-6 /°F) |
| 20 - 250 (68-482) |
11 (6.1) |
| 20 - 500 (68-932) |
12 (6.7) |
| 20 - 750 (68-1382) |
14 (7.8) |
| 20 - 1000 (68-1832) |
15 (8.3) |
Thermal conductivity
| Temperature °C |
50 |
600 |
800 |
1000 |
1200 |
| Temperature °F |
122 |
1112 |
1472 |
1832 |
2192 |
| W m-1 K-1 |
11 |
20 |
22 |
26 |
27 |
| Btu h-1ft-1°F-1 |
6.4 |
11.6 |
12.7 |
15.0 |
15.6 |
Specific heat capacity
| Temperature °C |
20 |
200 |
400 |
600 |
800 |
1000 |
1200 |
| Temperature °F |
68 |
392 |
752 |
1112 |
1472 |
1832 |
2192 |
| kJ kg-1 K-1 |
0.46 |
0.56 |
0.63 |
0.75 |
0.71 |
0.72 |
0.74 |
| Btu lb-1 °F-1 |
0.11 |
0.13 |
0.15 |
0.18 |
0.17 |
0.17 |
0.18 |
| Melting point °C (°F) |
1500 (2732) |
| Max continuous operating temperature in air °C (°F) |
1300 (2372) |
| Magnetic properties |
The material is magnetic up to approximately 600°C (1112°F)(Curie point). |
| Emissivity - fully oxidized material |
0.70 |
