Designation by Standards

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

Heat resisting ferritic steel. Heat resistance in air up to 1150oC.

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.

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

Hot forming temperature: 1100-750oC.

Slow speeds and positive feeds combined with rigid mounts and sharp tooling surfaces optimize machining 446.

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.

All technical information is for reference only.