446

446

446 is a high chromium ferritic heat resistant alloy with excellent resistance to oxidation, sulfidation and other forms of hot corrosion. This grade is most commonly used between 1500 - 2100°F, although its elevated temperature strength is quite low. 446 is the only heat resistant alloy that will tolerate molten copper and brass. As with other high chromium ferritic stainless, 446 embrittles severely in the 700-1000°F temperature range (885°F embrittlement). 446 should not be used in this temperature range unless nearly complete loss of room temperature ductility may be tolerated. Sigma phase embrittlement occurs upon long time exposure in the 1000-1300°F range.

446 has a high ductile-to-brittle impact transition temperature. Therefore, successful forming and bending is aided by low forming speeds, edge preparation and preheating to 250-400°F. Annealing, when necessary should be performed at 1550-1650°F followed by rapid cool.

Welding may be accomplished by conventional methods. Preheating and postheating to 300-600°F is helpful. Austenitic weld fillers, such as AWS E310 or E312 are generally suggested to maximize weld deposit ductility.

Chemistry

 CrCNMnSiPhSFe
MIN 23.0 - - - - - - -
MAX 27.0 0.15 0.25 1.5 1.0 0.04 0.03 Balance

Specifications

ASTM A 240, ASTM A 276, ASTM A 276 Condition A, ASTM A 276 Condition S
EN 1.4763
UNS S44600
Werkstoff 1.4763

Inventory

446 Flat Bar, 446 Plate, 446 Round Bar, 446 Square Bar

Common Trade Names

446 Stainless

Features

  • Oxidation resistance through 2000°F
  • Sulfidation resistance
  • Good thermal conductivity
  • Resistance to molten copper
  • Low strength

Applications

  • Neutral salt pot electrodes
  • Recuperators
  • Spouts for conveying molten copper alloys
  • Oil burner parts
  • Combustion chambers
  • Furnace and kiln linings
  • Stack dampers
  • Boiler baffles
  • Glass molds
  • Soot blowers

Physical Properties

Density: 0.270 lb/inch3
Melting Point: 2640 - 2710°F

Temperature, °F 70 1200 1400 1600 1800
Coefficient* of Thermal Expansion, in/in°F x 10-6 - 6.3 6.4 6.7 7.3
Thermal Conductivity
Btu • ft/ft2 • hr • °F
13.2 18.8 19.9 20.8 21.6
Modulus of Elasticity Dynamic, psi x 106 30.4 20.0 -   -

* 70°F to indicated temperature.

Mechanical Properties

Representative Tensile Properties

Temperature, °F 70 1000 1100 1200 1300 1400
Ultimate Tensile Strength, ksi 68 52.7 27.7 15.0 10.5 5.0
0.2% Yield Strength, ksi 50 42.3 23 12 9.0 4.0
Elongation, % 30 27 65 90 113 128
Hardness, Rb 89 - 93 - -     -

Typical Creep- Rupture Properties

Temperature, °F 1400 1600 1800
Minimum Creep 0.0001%/Hour, ksi 0.26 - -
10,000 Hour Rupture Strength, ksi 1.1 0.45 0.23