Nitronic 40 Stainless Steel - UNS S21900, S21904, XM10, XM11

Nitronic 40 Stainless Steel is a nitrogen strengthened austenitic stainless steel with great versatility, combining high yield strength with good corrosion resistance. Room temperature yield strength is about twice that of Types 304, 321 and 347.

 

Nitronic 40 provides remarkably good elevated temperature properties and also retains its high strength and toughness at cryogenic temperatures.

 

It has good high temperature oxidation resistance in air and resists stress corrosion cracking in severe marine environments at ambient temperature. Its austenite is so stable that it remains essentially non-magnetic at cryogenic temperatures or after up to 60% cold work.

Nitronic 40 may be hot worked by the same methods used with other austenitic stainless steels. However the alloy is stronger and requires more power for forging. Heating for hot working should be in temperature range of 2100˚F to 2200˚F.

Although it has higher yield strength than Type 304, Nitronic 40 may be formed on the same fabricating equipment, with the same techniques, only more power. In-process annealing maybe done between 1950˚F to 2050˚F.

Final annealing is done at 1900˚F to 2000˚F followed by rapid cooling. Nitronic 40 cannot be hardened by heat treatment.

Nitronic 40 exhibits good resistance to high temperature oxidation in air. Its general corrosion resistance in chemical media, industrial and marine environments is similar to that of Type 304 stainless steel. Nitronic 40 has shown excellent stress-corrosion cracking resistance in tests for 15 years at ambient temperatures in severe seacoast atmospheres.

Nitronic 40 is machined to same methods as other austenitic stainless steels, and like those alloys, also work hardens during machining. This requires rigid tooling, heavy feeds and slower speeds.

Nitronic 40 is readily weldable using TIG, MIG and shielded metal arc welding methods. Like other Nitronic grades the high nitrogen content can interfere with electron beam welding by severe outgassing.

Nitronic 40 is useful in applications where low magnetic permeability is important because it remains essentially non-magnetic even in sub-zero temperatures or after severe cold working.