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