Ferritic SS 446

Ferritic SS 446

446 grade stainless steel composition is what makes it ferritic stainless steel which has good resistance to high temperature corrosion and oxidation. SS 446 is an alloy with high chromium ferritic properties and AISI 446 composition gives it better heat resistance and has excellent resistance to sulfidation, oxidation and other kinds of hot corrosion.

SS 446 chemical composition

GRADE Cu Ni Mn Si Ni C P S Fe
SS 446 MIN 23 29 BALANCE
MAX 27 33 1.5 1 0.25 0.2 0.04 0.03

AISI 446 composition doesn’t allow it to be used in the high temperature range unless a nearly complete loss of room temperature ductility may be in question. Sigma phase embrittlement happenswhen it is exposed in the 1000°F-1300°F range.

Corrosion Resistance 

Stainless steel 446 suppliers usually tell that this gradeis non-hardenable but has extra-ordinary corrosion resistance at elevated temperatures. SS 446 is a high chromium ferritic alloy resistant to heat which has excellent resistance to sulfidation, oxidation, and other types of hot corrosion.

SS 446 is an alloy with high chromium content with heat resistance along with sulfidation, oxidation, and other forms of hot corrosion. 446 stainless steel is used in multiples applications such as Recuperators, Spouts for conveying molten copper alloys, Neutral salt pot electrodes, Oil burner parts, and Combustion chambers.

Specifications of SS 446

GRADE UNS EN JIS ASTM
SS 446 S46600 1.4762 SUS 446 A 268, A 276, A 314, A 176

The ductility loss can be recovered in SS 446 by a little temperature hike at the range of temperatures of 700°C to 800°C. In the temperature range of 600°C to 900°C, 1.4762 has the affinity to sigma phase embrittlement, thus, after longer application within this range of temperature range, the ductile values are strongly reduced particularly at the range of 800ºC-900ºC.The steel should not be used in this temperature range if mechanical stress is in position.

Heat Treatment 

An interesting fact about SS 446 is that it is the only alloy with heat resistance that can tolerate molten copper and brass. AISI 446 composition enables it to create an impact on high ductile-to-brittle transition temperature. Whenever necessary, annealing should be performed at 1550-1650°F followed by rapid cool.

Physical Properties

Grade Density (g/cm3) Elastic Modulus (GPa) Coeff of Thermal Expansion (μm/m/°C) Thermal Conductivity (W/m.K)
SS 446 7.8 200 0-100°C 21.6
10.4

Weldability

446 stainless steel data sheet suggests it can be easily welded using traditional methods except oxyacetylene welding. Chrome steels with ferritic properties are heat sensitive. Therefore, the 446 stainless steel should be welded with the heat with the lowest possible input by using thin electrode diameter, low current intensity and stringer bead welding.

Type 308 Welding Material can be used while welding SS 446, however, it does not resemble any resistance to scaling equivalent to the base metal. While welding, AISI 446 composition has to be taken care of regarding the difference in coefficient of thermal expansion of the base and weld metal too.

Applications of SS 446

SS 446 is severely embrittled in the temperature range of 700°F-1000°F thus it is used in various applications including Recuperators, Oil burner parts, Neutral salt pot electrodes, Spouts for conveying molten copper alloys, and Combustion chambers, etc.

Some of the popular applications of SS 446 are:

  • 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