Chemical composition and properties of FeCrAl alloys:
The chemical composition in w-% of different FeCrAl alloys are shown in the table below;
The scaling temperature is that temperature where the protecting oxide starts to crack and fall of with a high rate.
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| Trade Mark | % Cr | % Al | Other additions | Scaling temp in air, at constant temperature, degrees C (F) |
| Kanthal APM | 22 | 5.8 | 1425(2600F) | |
| Kanthal APMT | 21 | 5.0 | Mo 3.0 | 1425(2600F) |
| Kanthal A-1 | 22 | 5.8 | 1400(2550F) | |
| Kanthal AF | 22 | 5.3 | Y | 1300(2370F) |
|
Kanthal D |
22 | 4.8 | 1300(1300F) | |
| Alkrothal | 15 | 4.3 | 1100(2010F) |
The high aluminum content, in combination with the high chromium content causes the scaling temperature to increase up to 1425 C (2600F ); Under the headline heat resistance, these FeCrAl alloys are compared with commonly used Fe and Ni base alloys. As can be seen from that table, the FeCrAl alloys have superior properties as compared to the other alloys in most environments.
It should be noted that, during alternating temperature conditions, the yttrium addition to the AF alloy which also is known as the Fecralloys alloys, improves the adherence of the protecting oxide, making the service life of components in the AF alloy longer than that of the A-1 grade.
Kanthal APM and APMT ferritic super alloys!
Kanthal APM and APMT are manufactured by powder metallurgy, which increases the high temperature strength quite substantially. Kanthal APM can therefore be used also in applications where a high temperature strength (creep strength) is of importance. Thus, Kanthal APM is a ferritic super alloy. Kanthal APMT is a further development of Kanthal APM, having an even higher creep strength.
Product forms and availability
The FeCrAl alloys are available as wire, strip, welded and seamless tubes; All these product forms are available from stock for fast deliveries.
Properties of FeCrAl alloys
|
FeCrAl alloys i.e. Ferretic
stainless steel with aluminium |
Kanthal
AF, Fecralloy |
Kanthal
A-1 |
Kanthal
APM |
Kanthal
APMT |
Kanthal
D |
| Scaling temperature temperature in air °C (°F) | 1300 (2372) | 1400 (2552) | 1425 (2597) | 1425 (2597) | 1300 (2372) |
| Max continuous operating temperature in air °C (°F) | 1300 (2372) | 1400 (2552) | 1250 (2282) | 1250 (2282) | 1300 (2372) |
| Nominal chemical composition, % | |||||
| Cr | 22 | 22 | 22 | 21 | 22 |
| Al | 5.3 | 5.8 | 5.8 | 5.0 | 4.8 |
| Y | Addition | - | - | - | - |
| Fe | Balance | Balance | Balance | Balance | Balance |
| Mo | - | - | - | 3.0 | - |
| Density, g/cm3 (lb/in3) | 7.15 (0.259) | 7.10 (0.256) | 7.10 (0.256) | 7.25 (0.262) | 7.25 (0.262) |
| Electrical resistivity at 20°C Ω mm2/m | 1.39 | 1.45 | 1.45 | 1.40 | 1.35 |
| Temperature factor of the resistivity, Ct | |||||
| 600°C (1112°F) | 1.04 | 1.02 | 1.02 | 1.02 | 1.04 |
| 800°C (1472°F) | 1.05 | 1.03 | 1.03 | 1.02 | 1.06 |
| 1000°C (1832°F) | 1.06 | 1.04 | 1.04 | 1.03 | 1.07 |
| 1200°C (2192°F) | 1.06 | 1.04 | 1.04 | 1.03 | 1.08 |
| Coefficiency of thermal expansion, x 10-6/K | |||||
| 20-250°C (68-482°F) | 11 | 11 | 11 | 12.4 | 11 |
| 20-500°C (68-932°F) | 12 | 12 | 12 | 13.1 | 12 |
| 20-750°C (68-1382°F) | 14 | 14 | 14 | 13.6 | 14 |
| 20-1000°C (68-1832°F) | 15 | 15 | 15 | 14.7 | 15 |
| 20-1200°C (68-2192°F) | - | - | 16 | 15.4 | - |
| 20-1400°C (68-2552°F) | - | - | 16 | - | - |
| Thermal conductivity, W m-1K-1 | |||||
| 20°C (68°F) | 11 | - | - | - | - |
| 50°C (122°F) | - | 11 | 11 | 11 | 11 |
| 600°C (1112°F) | 20 | 20 | 20 | 21 | 20 |
| 800°C (1472°F) | 22 | 22 | 22 | 23 | 22 |
| 1000°C (1832°F) | 26 | 26 | 26 | 27 | 26 |
| 1200°C (2192°F) | 27 | 27 | 27 | 29 | 27 |
| 1400°C (2552°F) | - | 35 | 35 | - | - |
| Specific heat capacity, kJ kg-1K-1 |
|||||
| 20°C (68°F) | 0.46 | 0.46 | 0.46 | 0.48 | 0.46 |
| 200°C (392°F) | 0.56 | 0.56 | 0.56 | 0.56 | 0.56 |
| 400°C (752°F) | 0.63 | 0.63 | 0.63 | 0.64 | 0.63 |
| 600°C (1112°F) | 0.75 | 0.75 | 0.75 | 0.71 | 0.75 |
| 800°C (1472°F) | 0.71 | 0.71 | 0.71 | 0.67 | 0.71 |
| 1000°C (1832°F) | 0.72 | 0.72 | 0.72 | 0.69 | 0.72 |
| 1200°C (2192°F) | 0.74 | 0.74 | 0.74 | 0.70 | 0.74 |
| 1400°C (2552°F) | - | 0.80 | 0.80 | - | - |
| Melting point, °C (°F) | 1500 (2732) | 1500 (2732) | 1500 (2732) | 1500 (2732) | 1500 (2732) |
| Mechanical properties | |||||
| Tensil strength, MPa | 650 | 670 | 670 | 742 | 630 |
| Yield point, MPa | 470 | 460 | 450 | 540 | 470 |
| Hardness, Hv | 230 | 225 | 225 | 250 | 220 |
| Elongation, % | 20 | 22 | 27 | 26 | 21 |
| Creep strength - 1% elongation in 1000h, MPa | |||||
| 800°C (1472°F) | - | 1.2 | - | 21.9 | 1.2 |
| 900°C (1652°F) | - | - | 5.9 | 15.6 | - |
| 1000°C (1832°F) | - | 0.5 | 2.0 | 10.9 | 0.5 |
| 1100°C (2012°F) | 0.7 | - | 0.7 | 5.0 | - |
| 1200°C (2192°F) | 0.3 | - | 0.3 | 2.1 | - |
| Magnetic properties (Currie point) |
The material is magnetic up to approximately 600°C (1112°F) | The material is magnetic up to approximately 600°C (1112°F) | The material is magnetic up to approximately 600°C (1112°F) | The material is magnetic up to approximately 600°C (1112°F) | The material is magnetic up to approximately 600°C (1112°F) |
| Emissivity - fully oxidized material | 0.70 | 0.70 | 0.70 | 0.70 | 0.70 |