Nitronic 50: A High Strength and Corrosion Resistant Austenitic Stainless Steel
Alloy Definition and Chemical Composition
Nitronic 50 brings together high strength, excellent corrosion resistance and good ductility properties. It is an austenitic stainless steel. It essentially contains the elements iron, chromium (20–23%), nickel (11–13%), manganese (4–6%) and molybdenum (1.5–3%). The high manganese and nitrogen addition both increases strength and greatly improves resistance to rusting compared with the classic 300 series stainless steels.
Nitronic 50 is used especially in sea water environments, chemical process systems, nuclear energy components and highly stressed fastening elements. In terms of tensile and yield strength it doubles standard austenitic stainless steels such as 304L and 316L.
Typical chemical composition (% by weight):
- Chromium (Cr): 20.5 – 23.5
- Nickel (Ni): 11.5 – 13.5
- Molybdenum (Mo): 1.5 – 3.0
- Manganese (Mn): 4.0 – 6.0
- Nitrogen (N): 0.20 – 0.40
- Silicon (Si): ≤1.0
- Carbon (C): ≤0.06
- Phosphorus (P): ≤0.04
- Sulphur (S): ≤0.03
- Iron (Fe): Balance
The nitrogen element dissolves in interstitial solid solution and thereby increases the yield strength by up to 50% and improves the pitting corrosion resistance.
Nitronic 50 Standards and Specifications
Nitronic 50 has been defined in the following standards:
- UNS S20910 – Unified Numbering System
- ASTM A276 / A479 – Bar, section and forged products
- ASTM A182 – Forged flanges and fittings
- ASTM A240 – Sheet and plate products
- ASME SA-479 – Suitability for pressure vessel construction
- AMS 5764 – Special form for aerospace applications
Nitronic 50 can be supplied in both annealed (solution treated) and high-strength (cold worked or cold drawn) form.
Nitronic 50 Trade Names and Equivalent Alloys
- Nitronic® 50 – Name registered by AK Steel (now Cleveland-Cliffs)
- XM-19 – Its other common equivalent name
- UNS S20910 – Its chemically fixed designation
- Other trade marks: Armco Nitronic 50, AL-6XN (partial similarity)
Nitronic 50 Mechanical and Physical Properties
Nitronic 50 is an austenitic steel able to preserve its mechanical strength both at low and at high temperatures. It is not magnetic and provides an advantage in the production of high strength fastening elements.
In the solution treated (annealed) condition:
- Tensile strength (UTS): 690 – 760 MPa
- Yield strength (0.2%): 380 – 485 MPa
- Elongation (%): 35 – 45
- Hardness (Brinell): ~230 HB
- Density: 7.9 g/cm³
- Melting range: 1370–1395 °C
- Temperature strength: Structural stability up to 870 °C
In the cold worked (high strength) condition:
- Tensile strength: >1000 MPa
- Yield strength: >690 MPa
Nitronic 50 is somewhat more difficult than 316L in terms of machinability, but machining is possible with modern CNC systems.
Application Areas
Nitronic 50 is preferred across a broad spectrum of industrial applications, especially in environments where corrosion and mechanical strength are required at the same time:
1.Marine and Offshore
#Pumps, valves, shafts, propeller shafts, chains, fastening elements
2Chemical Process Industry
#Tanks and reactors in environments containing acid and chlorine
3.Energy and Nuclear Sector
#Pipe systems, gaskets, pipe hanger systems, heat exchanger elements
4.Aerospace
#High strength, non-magnetic fasteners
5.Medical and Food Sector
#Durable fasteners used in sterile environments
Advantages
- High Yield Strength: It offers approximately twice the yield strength of 316L.
- Excellent Corrosion Resistance: It is durable against a broad corrosion spectrum including sea water, chlorine ions, organic acids and oxidising environments.
- Being Non-Magnetic: It offers low magnetic permeability in most applications. It is preferred in MRI and precision electronic systems.
- Good Weldability: It can be welded without problems by the MIG, TIG and resistance welding methods.
- High Fatigue Strength: It provides a long life in systems exposed to dynamic loads.
Disadvantages
- High Cost: Because of the proportion of alloying elements it is more expensive than the 300 series steels.
- Machinability Difficulty: The high strength makes chip removal difficult. It may cause cutting tip wear.
- Risk of Magnetism After Annealing: Cold worked forms may acquire slight magnetic properties over time.
- Carbon Content and Welding: Although the carbon ratio is low, carbide precipitation may form at the grain boundaries in welds with high heat input; solution annealing is recommended.
Conclusion and Engineering Evaluation
Nitronic 50 is one of the rare alloys offering, beyond the classic stainless steels, both high strength and high corrosion resistance. In applications where engineers in the marine, chemical, energy and aerospace sectors seek high performance solutions, it stands out with mechanical properties superior to those of 316L and 317L.
Thanks to its high strength it provides weight reduction and structural compactness in cases where thinner section designs are possible. Together with its non-magnetic structure it is also preferred in MRI devices, medical devices and applications requiring electromagnetic shielding.
#UNSS20910
#ASTMA276
#ASTMA182
#ASTMA240
#ASMESA-479
#AMS5764
#Nitronic®50
#UNS S20910
We supply this material
We supply Nitronic 50 (1.3964) — to the AMS 5764 standard, in the dimensions and forms required. Contact us for stock availability and pricing.
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