Nitronic 50 (XM-19) – UNS S20910
High-nitrogen, high-strength austenitic stainless steel
Cr-Ni-Mn-N austenitic stainless with Nb and V. It has nearly twice the yield strength of 316L in the annealed condition and corrosion resistance superior to 316/317L. It stays non-magnetic even after severe cold work and keeps its toughness at cryogenic temperatures.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | S20910 |
| W.Nr./EN | No direct EN equivalent (1.3964 is similar but has 15–17% Ni) |
| DIN | X2CrNiMnMoNNb21-16-5-3 (approx.) |
| Trade names | Nitronic 50 (Cleveland-Cliffs), XM-19 (XM19), Type XM-19 |
| Others | ASTM A276 / A479 Type XM-19; 22-13-5 |
Standards by product form
| Form | Standard |
|---|---|
| Bar | ASTM A276 / A479 Type XM-19 (UNS S20910) |
| Forging/flange | ASTM A182 FXM-19 |
| Plate | ASTM A240 XM-19 |
| Tube | ASTM A312 TPXM-19 |
| Aerospace | AMS 5764 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7222.30.00 | 7222.30 | 7222.30.0024 | 7222 30 51 |
| Hot-rolled bar | 7222.11.00 | 7222.11 | 7222.11.0059 | 7222 11 11 |
| Plate (> 10 mm, width ≥ 600 mm) | 7219.21.00 | 7219.21 | 7219.21.0020 | 7219 21 10 |
| Seamless pipe | 7304.41.90 | 7304.41 | 7304.41.6045 | 7304 41 00 |
| Welded pipe | 7306.40.00 | 7306.40 | 7306.40.5085 | 7306 40 80 |
| Flange and fitting | 7307.21.00 | 7307.21 | 7307.21.5000 | 7307 21 00 |
Tariff class: stainless steel (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM A479 (XM-19)
| Element | Range (%) |
|---|---|
| C | ≤ 0.06 |
| Mn | 4.0 – 6.0 |
| P | ≤ 0.045 |
| S | ≤ 0.030 |
| Si | ≤ 1.00 |
| Cr | 20.5 – 23.5 |
| Ni | 11.5 – 13.5 |
| Mo | 1.50 – 3.00 |
| N | 0.20 – 0.40 |
| Nb | 0.10 – 0.30 |
| V | 0.10 – 0.30 |
| Fe | balance |
Mechanical properties
Annealed (ASTM A479 XM-19); 'High Strength' condition available in bar
| Property | Value |
|---|---|
| Yield strength (0.2%) | ≥ 380 MPa |
| Tensile strength | ≥ 690 MPa |
| Elongation | ≥ 35% |
| Reduction of area | ≥ 55% |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.88 g/cm³ |
| Melting range | 1,415 – 1,450 °C |
| Modulus of elasticity | 197 GPa |
| Thermal conductivity (150 °C) | ≈ 15.6 W/m·K |
| Thermal expansion (20–100 °C) | ≈ 16.2 µm/m·K |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Cryogenic (–196 °C) up to ≈ 650 °C in corrosion/light structural service; do not use where prolonged sensitization is critical without evaluation. |
| Heat treatment | Annealing 1,065 – 1,120 °C with rapid water quench. Not hardenable by quenching; HS condition obtained by controlled hot working. |
| Welding | Good. Consumable AWS ER209 / E209 (matching alloy). |
| Machining | Harder than 316L because of the higher strength and work hardening: cutting speed ≈ 50–60% of 316, carbide tooling and a rigid machine. |
Filler metal for welding
The wire composition is usually not identical to the material: each page explains why.
Typical applications
- Seawater pump and propulsion shafts
- Valve stems and studs
- Offshore components and sour service (NACE MR0175)
- Marine hardware
- Cryogenic and non-magnetic equipment
- Pulp and paper
Alternatives: 316L when mechanical strength is not critical; duplex 2205/super duplex for shafts in chlorides (but magnetic); Nitronic 60 (UNS S21800) for galling and wear resistance.
Nitronic 50 (XM-19): complete guide
What Nitronic 50 is
Nitronic 50, designated XM-19 in ASTM standards (UNS S20910), belongs to the family of austenitic stainless steels, in the nitrogen-bearing group. Nitrogen in solid solution (0.20 – 0.40%) and niobium and vanadium carbonitrides raise the yield strength to 380 MPa in the solution-annealed condition, versus 170 MPa for 316L, with no loss of toughness and no magnetism.
Chemical composition and role of the elements
The high manganese increases nitrogen solubility; nitrogen and molybdenum raise pitting and crevice resistance (PREN ≈ 29 – 40, typically 34); niobium and vanadium refine the grain and harden by fine precipitation. Residual elements such as aluminum, boron, copper and tungsten are not specified by the standard.
Corrosion and limits of use
It resists pitting, crevice corrosion and chloride stress corrosion cracking better than 316L and 317L, and performs well in flowing seawater.
For stems, seats and pins where the main problem is galling between stainless parts, the alloy to use is Nitronic 60.
Applications
Pump and ship propeller shafts, valve stems, non-magnetic fasteners and chains, marine and offshore equipment components, heat exchangers, instrumentation parts on platforms and cryogenic components.
Supply forms and Dustre services
Round bars and blocks forged in open die, cut to size on a band saw, with rough or finish machining, solution annealing in our own furnaces and hardness, tensile and impact testing. All material is supplied with a 3.1 inspection certificate and heat traceability.
Frequently asked questions
What is the chemical composition of Nitronic 50 (XM-19)?
Per ASTM A479 (XM-19): C ≤ 0.06; Mn 4.0 – 6.0; P ≤ 0.045; S ≤ 0.030; Si ≤ 1.00; Cr 20.5 – 23.5.
Which standards cover Nitronic 50 (XM-19)?
Bar: ASTM A276 / A479 Type XM-19 (UNS S20910). Forging/flange: ASTM A182 FXM-19. Plate: ASTM A240 XM-19. Tube: ASTM A312 TPXM-19. Aerospace: AMS 5764.
Up to what temperature can Nitronic 50 (XM-19) be used?
Cryogenic (–196 °C) up to ≈ 650 °C in corrosion/light structural service; do not use where prolonged sensitization is critical without evaluation.
Which materials can replace Nitronic 50 (XM-19)?
316L when mechanical strength is not critical; duplex 2205/super duplex for shafts in chlorides (but magnetic); Nitronic 60 (UNS S21800) for galling and wear resistance.
Are Nitronic 50 and XM-19 the same steel?
Yes. XM-19 is the ASTM designation (ASTM A276 / A479 Type XM-19, A182 FXM-19, A240 XM-19) of UNS S20910; Nitronic 50 is the Cleveland-Cliffs trade name for the same alloy. On orders and certificates, the ASTM grade and UNS number govern.
