Kanthal® APMT tubes is an advanced powder metallurgical, dispersion strengthened, ferritic iron-chromium-aluminium alloy (FeCrAlMo alloy) which is used at tube temperatures up to 1250°C (2280°F).
Kanthal® APMT tubes have good form stability at high temperature. Kanthal® APMT forms an excellent, non-scaling surface oxide, which gives good protection in most furnace environments, i.e. oxidizing, sulphurous and carburizing, as well as against deposits of carbon, ash, etc. The combination of excellent oxidation properties and form stability makes the alloy unique.
Typical applications for Kanthal® APMT are as radiant tubes in electrically or gas fired furnaces such as continuous annealing and galvanizing furnaces, seal quench furnaces, holding furnaces and dosing furnaces in the aluminium, zinc, lead industries, thermocouple protection tubes, furnace muffles for sintering applications.
Chemical composition
| C % | Si % | Mn % | Mo % | Cr % | Al % | Fe % | |
|---|---|---|---|---|---|---|---|
| Nominal composition | 3.0 | 21.0 | 5.0 | Balance | |||
| Min | - | - | - | 20.5 | - | ||
| Max | 0.08 | 0.7 | 0.4 | 23.5 | - |
Corrosion resistance
| Maximum recommended operating temperature in air °C (°F) | 1250 (2280) |
|---|---|
| Protective surface oxide | Al2O3 |
Oxidation rate
Weight gain of Kanthal APMT, due to oxide formation, when oxidized in air at 1200°C for 100h cycles with cooling to ambient temperature between each cycle.
Mechanical properties
| Yield strength | Tensile strength | Elongation | Hardness |
|---|---|---|---|
| Rp0.2 | Rm | A | |
| MPa (ksi) | MPa (ksi) | % | Hv |
| 540 (78) | 740 (107) | 26 | 250 |
Remark: The samples are taken in the longitudinal direction from tube in delivery condition.
Mechanical properties at elevated temperature
| Temperature °C F) | 800 (1472) | 900 (1652) | 1000 (1832) | 1100 (2012) | 1200 (2192) |
|---|---|---|---|---|---|
| MPa (ksi) | 21.9 (3200) | 15.6 (2300 | 10.9 (1600) | 5.0 (730) | 2.1 (300) |
Remark: The samples are taken in the longitudinal direction from tube in delivery condition. Typical typical initial average grain size is 30-50μm.
| Creep rate | Temperature / Stress | ||||
|---|---|---|---|---|---|
| s-1 | 800°C (1472°F) |
900°C (1652°F) |
1000°C (1832°F) |
1100°C (2012°F) |
1200°C (2192°F) |
| MPa (psi) | MPa (psi) | MPa (psi) | MPa (psi) | MPa (psi) | |
| 1.0 e-10 | 20.7 (3000) | 12.7 (1800) | 7.7 (1100) | 3.0 (440) | 1.2 (170) |
| 1.0 e-8 | 25.5 (3700) | 18.0 (2600) | 13.0 (1900) | 6.9 (1000) | 3.0 (440) |
| 1.0 e-6 | 30.8 (4500) | 25.5 (3700) | 22.2 (3200) | 16.2 (2300) | 7.3 (1100) |
| Time | Temperature / Stress | ||||
|---|---|---|---|---|---|
| h | 800°C (1472°F) |
900°C (1652°F) |
1000°C (1832°F) |
1100°C (2012°F) |
1200°C (2192°F) |
| MPa (psi) | MPa (psi) | MPa (psi) | MPa (psi) | MPa (psi) | |
| 100 | 28.8 (4200) | 22.0 (3200) | 17.9 (2600) | 10.1 (1500) | 5.0 (730) |
| 1000 | 25.3 (3700) | 17.3 (2500) | 12.3 (1800) | 6.0 (870) | 2.5 (360) |
| 10000 | 22.0 (3200) | 13.8 (2000) | 8.1 (1200) | 3.5 (510) | 1.3 (190) |
Physical properties
| Density g/cm3 (lb/in3) | 7.25 (0.262) |
|---|---|
| Electrical resistivity at 20°C Ω mm2/m (Ω circ. mil/ft) | 1.40 (842) |
| Poisson's ratio | 0.30 |
| 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 °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 | 1.00 | 1.01 | 1.01 | 1.01 | 1.02 | 1.02 | 1.02 | 1.03 | 1.03 | 1.03 | 1.03 | 1.04 |
| Temperature °C (°F) | Thermal Expansion x 10-6/K (10-6 /°F) |
|---|---|
| 20 - 250 (68-482) | 12.4 (6.89) |
| 20 - 500 (68-932) | 13.1 (7.28) |
| 20 - 750 (68-1382) | 13.6 (7.56) |
| 20 - 1000 (68-1832) | 14.7 (8.17) |
| 20 - 1200 (68-2192) | 15.4 (8.56) |
| Temperature °C (°F) | 50 (122) | 600 (1112) | 800 (1472) | 1000 (1832) | 1200 (2192) |
|---|---|---|---|---|---|
| W m-1 K-1 (Btu h-1ft-1°F-1) | 11 (6.4) | 21 (12.1) | 23 (13.3) | 27 (15.6) | 29 (16.8) |
| Temperature °C | 20 | 200 | 400 | 600 | 800 | 1000 | 1200 |
|---|---|---|---|---|---|---|---|
| Temperature °F | 68 | 392 | 752 | 1112 | 1472 | 1932 | 2192 |
| kJ kg-1 K-1 | 0.48 | 0.56 | 0.64 | 0.71 | 0.67 | 0.69 | 0.70 |
| Btu lb-1 °F-1 | 0.11 | 0.13 | 0.15 | 0.17 | 0.16 | 0.16 | 0.17 |
| Melting point °C (°F) | 1500 (2732) |
|---|---|
| Magnetic properties | The material is magnetic up to approximately 600°C (1112°F) (Curie point). |
| Emissivity - fully oxidized material | 0.70 |