Designation by Standards
| Steel No. | DIN | EN | AISI | JIS | ГОСТ |
| 1.4762 | X10CrAl24 † | X10CrAlSi25 | 446 | SUH446 | 15Ch28 |
Chemical Composition (in weight %)
| C | Si | Mn | Cr | Mo | Ni | V | W | Others |
| max. 0.12 | 1.05 | max. 1.00 | 24.50 | - | - | - | - | Al=1.45 |
Description
Heat resisting ferritic steel. Heat resistance in air up to 1150oC.
Applications
Annealing and hardening shops: Boxes, pots, muffles, retorts, pans and tubs for all kinds of heat treatment. Heating rods and plates.
Furnace and steam boiler construction: Grates and grate segments, fittings, conveyor parts, suporting and walking beams, rails, pistons, axle rollers, doors, slides, flaps, casings, recuperators, fans, superheater suspensions, pipe clamps, soot blower tubes.
Glass, porcelain, enamelling, cement and ceramics industries: Burner nozzels, rings, segments and other parts for rotary and lepols kilns.
General engineering: Grate bars, valves and spindles, stirring arms and teeth, thermocouple protecting tubes, fittings, drums, screws, nuts, rivets.
Petroleum industry: Tubes and tubular parts.
Physical properties (avarage values) at ambient temperature
Modulus of elasticity [103 x N/mm2]: 220, 208 (200oC), 192 (400oC), 172 (600oC)
Density [g/cm3]: 7.7
Thermal conductivity [W/m.K]: 17.0, 23.0 (500oC)
Electric resistivity [Ohm mm2/m]: 1.1
Specific heat capacity[J/g.K]: 0.45
Mechanical properties at ambient temperature
Hardness: max. 223 HB
0.2 % proof stress: min. 280 N/mm2
Tensile strength: 520-720 N/mm2
Elongation: 10% (Longt.), 7% (Transv.)
Resistance to:
Oxydizing: very high
Reducing: high
Nitrogenous and low-oxygen gasses: low
Carburization: medium
Maximum operating temperature in air: 1150oC.
Coefficient of Linear Thermal Expansion 10-6 oC-1
| 20-200oC | 20-400oC | 20-600oC | 20-800oC | 20-1000oC |
| 10.5 | 11.5 | 12.0 | 12.5 | 13.5 |
Soft Annealing or Quenching
Heat to 780-850oC, then quenching in air or water. Structure of heat treated steel is ferrite.
Hardening
This alloy does not respond to heat treatment.
1% Creep Limit in N/mm2 vs. Temperature in oC
| Hours | 500oC | 600oC | 700oC | 800oC | 900oC |
| 1 000 | 80 | 27.5 | 8.5 | 3.7 | 1.8 |
| 10 000 | 50 | 17.5 | 4.7 | 2.1 | 1.0 |
Creep Rupture Strength in N/mm2 vs. Temperature in oC
| Hours | 500oC | 600oC | 700oC | 800oC | 900oC |
| 1 000 | 160 | 55 | 17.0 | 7.5 | 3.6 |
| 10 000 | 100 | 35 | 9.5 | 4.3 | 1.9 |
| 100 000 | 55 | 20 | 5.0 | 2.3 | 1.0 |
Forging
Hot forming temperature: 1100-750oC.
Machinability
Slow speeds and positive feeds combined with rigid mounts and sharp tooling surfaces optimize machining 446.
Welding
Most common welding methods can be successfully employed with this alloy. Type 308 welding material may be used, but will not display scaling resistance equal to the base metal. Consideration must be given to the differences in coefficient of thermal expansion of base and weld metal. Oxyacetylene welding is not recommended.
Cold working
Due to its elevated chromium content, 446 is more difficult than other stainless steels to bend, draw, spin and weld.
Remark
All technical information is for reference only.