Fermonic® 50
Also known as Nitronic® 50, UNS S20910, EN 1.3964
Fermonic® 50 is a nitrogen-strengthened austenitic stainless steel with about twice the yield strength of 316.
Fermonic® 50 (UNS S20910) is a nitrogen-strengthened austenitic stainless steel providing approximately twice the minimum yield strength of Types 316 and 316L, while retaining excellent ductility and superior corrosion resistance. Its higher chromium, molybdenum and nitrogen content delivers better pitting and crevice corrosion resistance than 316 stainless in chloride environments.
Available as standard annealed bar and in cold worked or warm worked high-strength and extra-high-strength conditions, up to a proof stress of 862 N/mm² for the most demanding structural applications. Listed in NACE MR0175 / ISO 15156 for sour service.
We stock bar in the UK and USA. Plate, tube and fittings are available on enquiry; forgings and castings to order.
- Approximately twice the yield strength of Types 316 and 316L stainless steel
- Superior pitting and crevice corrosion resistance to 316 stainless
- Excellent ductility and toughness maintained in high-strength conditions
- Non-magnetic, even after cold working
- Listed in NACE MR0175 / ISO 15156 for sour service
| Element | Min | Max |
|---|---|---|
| Iron (Fe) | Bal | |
| Chromium (Cr) | 20.50 | 23.50 |
| Nickel (Ni) | 11.50 | 13.50 |
| Manganese (Mn) | 4.00 | 6.00 |
| Molybdenum (Mo) | 1.50 | 3.00 |
| Niobium (Nb) | 0.10 | 0.30 |
| Vanadium (V) | 0.10 | 0.30 |
| Nitrogen (N) | 0.20 | 0.40 |
| Silicon (Si) | - | 1.00 |
| Phosphorus (P) | - | 0.045 |
| Sulphur (S) | - | 0.030 |
| Carbon (C) | - | 0.06 |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 55 ksi | 380 N/mm² |
| Tensile strength (min) | 100 ksi | 690 N/mm² |
| Elongation (5.65√S0 & 4D) | 35% | |
| Reduction of area | 55% | |
| Hardness (Brinell) | 293 max | |
| Impact strength (room temp) | 54 J av | |
| Impact strength (−60°C) | 27 J av (20 J min) |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 125 ksi | 862 N/mm² |
| Tensile strength (min) | 145 ksi | 1000 N/mm² |
| Elongation (5.65√S0 & 4D) | 12% | |
| Reduction of area | 40% | |
| Hardness | 328 HBN max |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 105 ksi | 725 N/mm² |
| Tensile strength (min) | 125 ksi | 827 N/mm² |
| Elongation (5.65√S0 & 4D) | 15% | |
| Reduction of area | 45% | |
| Hardness | 328 HBN max |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 105 ksi | 725 N/mm² |
| Tensile strength (min) | 125 ksi | 896 N/mm² |
| Elongation (5.65√S0 & 4D) | 20% | |
| Reduction of area | 50% | |
| Hardness | 25-35 HRC | |
| Impact strength (room temp) | 135 J | |
| Impact strength (−60°C) | 40 J |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 120 ksi | 827 N/mm² |
| Tensile strength (min) | 135 ksi | 930 N/mm² |
| Elongation (5.65√S0 & 4D) | 20% | |
| Reduction of area | 40% | |
| Hardness | 25-35 HRC | |
| Impact strength (room temp) | 135 J | |
| Impact strength (−60°C) | 40 J |
| Property | Value |
|---|---|
| Density (kg/m³) | 7880 |
| Magnetic permeability (20°C) | < 1.05 |
| Young's modulus (kN/mm²) | 197 |
| Specific electrical resistance, 20°C (µΩ.m) | 0.82 |
| Mean coefficient of thermal expansion, 20-100°C (m/m/°C) | 17.9 x 10⁻⁶ |
| Specific heat, 20°C (J/kg.K) | 475 |
| Thermal conductivity, 20°C (W/m.K) | 13.3 |
Equivalents & cross-references
Standard designations
- UNS
- S20910Unified Numbering System; also designated XM-19
- EN
- 1.3964European material number - preserved from prior aka field
- ASTM
- XM-19ASTM designation - confirmed in Langley datasheet A479Bar and shapes A276Bar and shapes A182Flanges and fittings A314Billets for forging
- AMS
- 5764Bar and wire
- NACE
- MR0175 / ISO 15156-3Sour service
- API
- 6AWellhead and tree equipment
Fermonic® 50 is also designated UNS S20910, EN 1.3964, ASTM XM-19, ASTM A479, ASTM A276, ASTM A182, ASTM A314, AMS 5764, NACE MR0175 / ISO 15156-3 and API 6A.
Trade name equivalents
-
Nitronic 50
Cleveland-Cliffs (formerly AK Steel)
Nitronic 50 is a trade name of Cleveland-Cliffs (formerly AK Steel) for Fermonic® 50.
Common questions
What is Fermonic 50?
Fermonic 50 (Annealed) is a nitrogen-strengthened austenitic stainless steel covered by UNS S20910, XM-19, ASTM A479, ASTM A276, ASTM A182, ASTM A314 and AMS 5764, and listed in NACE MR0175/ISO 15156-3 and API 6A. It is supplied in the annealed condition and provides almost double the yield strength of common austenitic grades such as Alloy 304 and Alloy 316L. Langley Alloys stocks it as bar; plate, tube and fittings are available on enquiry, and forgings and castings are to order.
What is Fermonic 50 used for?
Fermonic 50 is used for oil and gas downhole equipment; marine pumps, valves, masts, tie downs, fixtures and fittings; food processing equipment; process industry equipment for sulphuric, nitric and polythionic acid, urea production and organic and fatty acids; and pulp and paper valves and fittings. Its higher strength lets designers reduce section size, weight and cost.
Is Fermonic 50 non-magnetic and suitable for sour service?
Yes. Fermonic 50 remains fully austenitic, and therefore fully non-magnetic, even after severe cold working, making it suitable for sensor applications. It is listed in NACE MR0175 for sour service oilfield applications given its ability to resist sulphide stress cracking, and it achieves corrosion resistance equivalent to or better than Alloy 317L in a wide range of environments. It is also listed in food handling standards (FDA) as an acceptable material for food contact surfaces.
How strong is Fermonic 50 compared with standard stainless steels?
Fermonic 50 provides almost double the yield strength of Alloy 304 and Alloy 316L, with a 0.2% proof stress of 380 N/mm² (55 ksi), and higher strength can be achieved through cold working. It also offers higher resistance to abrasion, erosion and cavitation erosion than Alloy 304, 316L and 317L, while maintaining excellent ductility and toughness at both elevated and cryogenic temperatures.
What is Nitronic 50?
Nitronic 50 is a trade name used by Cleveland-Cliffs (formerly AK Steel) for UNS S20910, a nitrogen-strengthened austenitic stainless steel also designated XM-19. Langley Alloys stocks this alloy as Fermonic® 50 to ASTM A479, AMS 5764, NACE MR0175/ISO 15156-3, and API 6A.
What is XM-19 stainless steel?
XM-19 is the ASTM designation for UNS S20910, a nitrogen-strengthened austenitic stainless steel with high strength and excellent corrosion resistance. It is also known as Nitronic 50 and is stocked by Langley Alloys as Fermonic® 50 to ASTM A479, AMS 5764, and API 6A.
Is Fermonic 50 the same as Nitronic 50?
Yes. Fermonic® 50 is Langley Alloys' designation for UNS S20910, the same material sold by AK Steel as Nitronic 50. Both designations refer to a nitrogen-strengthened austenitic stainless steel meeting UNS S20910 (ASTM XM-19), ASTM A479, AMS 5764, and NACE MR0175/ISO 15156-3.
What is the UNS number for Nitronic 50?
The UNS number for Nitronic 50 is S20910. It is also designated XM-19 (ASTM), AMS 5764, ASTM A479, and listed in NACE MR0175/ISO 15156-3. Langley Alloys stocks this grade as Fermonic® 50.
What is the density of Fermonic 50?
Fermonic 50 has a density of approximately 7.88 g/cm³ (7880 kg/m³).
Fermonic® 50 bars are supplied peeled and polished; annealed bars are solution treated and water quenched, and high-strength bars are cold or warm worked to reach their strength.
Tools for this grade
Pitting & crevice resistance
Pitting & Crevice Resistance
Rank alloys by PREN and get an indicative pitting temperature for a chloride service. Pick a grade and a service temperature to see whether it has margin against pitting, or compare the range in the table below. A first-pass screen for chloride and seawater service.
| Grade | UNS | PREN | Indicative CPT | Relative pitting resistance |
|---|
Indicative screen, not a certified result. PREN ranks pitting resistance; the pitting temperature here is estimated from PREN (CPT ≈ 2.5 × PREN - 50), consistent with Langley's "PREN >40, CPT exceeding 50°C" for super duplex. Real critical pitting/crevice temperature depends on test method, product form, surface finish and service chemistry. Crevice corrosion starts well below the pitting temperature - allow a margin at gaskets, deposits and flange faces. Use certified data for design.
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