Nitronic 33 is a nitrogen-strengthened austenitic stainless steel that combines high yield strength with excellent toughness and ductility. It’s magnetic permeability remains very low after severe cold working and at cryogenic temperatures.

The alloy is superior to 304 stainless in at least five specific areas: (1) Yield strength in the annealed condition is approximately twice that of 304, (2) it has excellent strength and ductility at cryogenic temperatures, (3)has better stress corrosion cracking resistance than 304, (4) low magnetic permeability is retained at cryogenic temperatures and after severe cold working and, (5) resistance to wear and galling is superior to the standard austenitic stainless steels.

The corrosion resistance of Nitronic 33 is superior to 409 and, in general, is nearly equal to 304. In weak acid solutions, the corrosion resistance of Nitronic 33 approaches that of 304. In more aggressive media Nitronic 33 is somewhat less resistance than 304.

Nitronic 33 is markedly more resistant than 304 and 304L to stress corrosion cracking in hot chloride solutions at lower stress levels. At higher stress levels (approx. 50 ksi and above) they are equal. Like most stainless steels, Nitronic 33 is prone to pitting and crevice corrosion in seawater and other aggressive environments, and should not be used under these conditions unless cathodically protected.

Although Nitronic 33 is considerably stronger than the conventional austenitic stainless steels, the same fabricating equipment and techniques can generally be used.

Applications

• Cryogenic Service – tanks valves, piping, flanges, and structural supports
• Abrasion/Wear Resistance – screens, racks, and wear plates
• Electrical (low magnetic permeability) – conduit shielding, MRI scanner supports, fittings, underground transmission risers and pipe and electronic support members
• Marine – mine sweeper components and perming piers
• Nuclear – spent fuel casks (internal supports)
• Process Equipment – heat exchangers, pressure vessels and piping where 304 is borderline with respect to stress corrosion cracking.