Nitronic 50 High-Strength Stainless Steel Guide
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What Is Nitronic 50 (XM-19)?
Nitronic 50 (UNS S20910, XM-19, 22-13-5) is a nitrogen-strengthened austenitic stainless steel developed for applications that need substantially higher strength than 316L without losing corrosion resistance. Nitrogen is a powerful solid-solution strengthener, which is why this grade reaches roughly double the annealed yield strength of 316. The high manganese content raises nitrogen solubility, and the molybdenum plus nitrogen combination pushes pitting resistance above that of 316L and 317L. Nitronic is the recognized trade name for this family of grades and appears in ASTM standards as XM-19.
Chemical Composition
| Element | Limit (%, by weight) |
|---|---|
| Carbon | max 0.060 |
| Chromium | 20.50-23.50 |
| Nickel | 11.50-13.50 |
| Manganese | 4.0-6.0 |
| Molybdenum | 1.50-3.00 |
| Nitrogen | 0.20-0.40 |
| Silicon | max 1.00 |
| Sulfur | max 0.030 |
Mechanical Properties and Strength Advantage
| Property | Nitronic 50 (annealed bar, A276) | 316/316L (annealed bar, A276) |
|---|---|---|
| Yield strength, min (MPa) | 380 | 205 |
| Tensile strength, min (MPa) | 690 | 515 |
| Elongation, min (%) | 35 | 40 |
| Magnetic permeability | low, stays low after cold work | increases after cold work |
Cold-worked bar can reach yield strengths above 700 MPa, roughly triple the annealed 316 value, which is why Nitronic 50 is specified for pump shafts, boat shafts, and fasteners where diameter reduction saves weight and improves fatigue life. It also keeps useful strength during intermittent exposure to elevated temperatures, making it suitable for automotive valve applications and other high-heat components.
Applications
Pump shafts and boat shafts, where high yield strength resists bending and wear.
Marine hardware and seawater pumps, where pitting resistance matters.
Chemical and petrochemical equipment, pressure vessel internals, and heat exchangers.
Fasteners, studs, and valve stems in sulfide-bearing oil and gas service.
Non-magnetic components where cold working must not introduce a magnetic response.
Processing and Procurement Notes
Nitronic 50 machines with more tool wear than 316 because of its high strength; use rigid setups and positive-rake tooling. It welds with austenitic practice; matching filler such as ER209 or an over-alloyed nitrogen-bearing filler is recommended to keep the weld metal corrosion resistance and strength. When ordering bar, confirm the condition (annealed or cold-worked), the ASTM A276/A479 specification, the UNS number S20910, and request an EN 10204 3.1 certificate with the mechanical test results.
Common Misconceptions
'Nitronic 50 is a duplex grade.' No, it is fully austenitic; the strength comes from nitrogen in solid solution, not from a two-phase structure.
'It is the same as 316L.' Its yield strength and pitting resistance are higher, and the price reflects the difference; do not substitute 316L where S20910 is specified.
'It cannot be used at high temperature.' It resists scaling intermittently to high temperatures, but long-term creep design above about 650 °C still needs code-based evaluation; it is not a replacement for high-temperature grades.
Frequently Asked Questions
What is Nitronic 50 stainless steel?
It is a nitrogen-strengthened austenitic stainless steel, UNS S20910, also designated XM-19 in ASTM A276 and known commercially as 22-13-5 for its chromium-nickel-manganese levels.
How strong is Nitronic 50?
Annealed bar has a minimum yield strength of 380 MPa, about double that of 316L; cold-worked bar exceeds 700 MPa yield, roughly three times annealed 316.
Is Nitronic 50 corrosion resistant?
Yes. Pitting and crevice corrosion resistance are superior to 316L and 317L in most chloride and sulfide media, which is why it is used in marine and oil and gas service.
Is Nitronic 50 magnetic?
No. It has very low magnetic permeability and remains essentially non-magnetic even after heavy cold working, unlike standard 304 and 316.
What is Nitronic 50 used for?
Pump shafts, boat shafts, fasteners, valve stems, heat exchanger components, and marine or chemical equipment that needs high strength plus corrosion resistance.
What standards cover Nitronic 50 bar?
ASTM A276 and A479 (bar), A312 and A249 for pipe and tube, and A240 for plate, all under UNS S20910; EN equivalent is 1.3964 (X2CrNiMnMoNbN21-16-5-3) where cross-referencing is required.
