Nitronic 60 – UNS S21800
Galling- and wear-resistant austenitic stainless steel
Cr-Ni-Mn austenitic stainless steel with ≈ 4% silicon and nitrogen. Silicon and manganese inhibit wear, galling and fretting even in the annealed condition: in an unlubricated test, Nitronic 60 against Nitronic 60 galled only at 345 MPa, while 304 against 304 galled at 14 MPa. Typical annealed yield strength is 414 MPa, general corrosion resistance lies between 304 and 316, and chloride pitting resistance is better than 316.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | S21800 |
| W.Nr./EN | No direct EN equivalent |
| Trade names | Nitronic 60 (Cleveland-Cliffs), Alloy 218, N-60, Fermonic 60 |
| Others | Fasteners ASTM A193 B8S / A194 8S; cast CF10SMnN; consumable AWS ER218 (Nitronic 60W) |
Standards by product form
| Form | Standard |
|---|---|
| Bar and shapes | ASTM A276 / A479 S21800 |
| Plate, sheet and strip | ASTM A240 S21800 |
| Bar, forging and wire (aerospace) | AMS 5848 |
| Billet and bar for forging | ASTM A314 |
| Wire | ASTM A580 |
| Bolts and nuts | ASTM A193 B8S / A194 8S |
| Casting | ASTM A351 / A743 CF10SMnN |
| Pressure vessel | ASME Section VIII Div. 1 (UHA-23) |
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 |
| 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 A276 / A479 (UNS S21800)
| Element | Range (%) |
|---|---|
| C | ≤ 0.10 |
| Mn | 7.0 – 9.0 |
| Si | 3.5 – 4.5 |
| Cr | 16.0 – 18.0 |
| Ni | 8.0 – 9.0 |
| N | 0.08 – 0.18 |
| P | ≤ 0.060* |
| S | ≤ 0.030 |
| Mo | ≤ 0.75 |
| Cu | ≤ 0.75* |
| Fe | balance |
Mechanical properties
Annealed – typical values for Ø 25 mm bar (HPA/AK Steel); minimums for bar over 12.7 mm in brackets
| Property | Value |
|---|---|
| Yield strength (0.2%) | 414 MPa typical (≥ 345 MPa*) |
| Tensile strength | 710 MPa typical (≥ 655 MPa*) |
| Elongation (4D) | 64% typical (≥ 35%*) |
| Reduction of area | 74% typical (≥ 55%*) |
| Hardness | 95 HRB typical (170 – 255 HB) |
| Strain hardened (Nitronic 60 HS, level 3, up to Ø 89 mm) | UTS ≥ 1,103 MPa; YS ≥ 896 MPa |
Typical physical properties
| Property | Value |
|---|---|
| Density | 7.62 g/cm³ |
| Modulus of elasticity | 180 GPa |
| Thermal expansion (24 – 93 °C) | ≈ 15.8 µm/m·K |
| Electrical resistivity | 98.2 µΩ·cm |
| Magnetic permeability (annealed) | 1.003 |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | From cryogenic (–196 °C, where it keeps its galling resistance) to high temperature: oxidation resistance similar to 309 and good strength up to ≈ 980 °C (1,800 °F). |
| Heat treatment | Solution anneal at ≈ 1,065 °C (1,950 °F)* with rapid cooling. Not hardenable by heat treatment; strength is raised by cold work (Nitronic 60 HS), which does not improve galling resistance. |
| Welding | Good, by the usual stainless steel processes. Matching consumable AWS A5.9 ER218 (Nitronic 60W). Preheat and post-weld heat treatment are generally not needed beyond normal stress relief. |
| Machining | Difficult: rating ≈ 23% (AISI B1112 = 100%; 304 = 45%). Machine at ≈ 50% of the speeds used for 304, with coated carbide, a rigid machine and enough power. |
Typical applications
- Valve stems, seats and trim
- Pump wear rings and lobes
- Pins, bushings and roller bearings
- Anti-galling bolts, nuts and studs (A193 B8S)
- Bridge pins and critical construction parts
- Screens, chains and drive systems
- Oil and gas, petrochemical and chemical processing components
Alternatives: Nitronic 50 (XM-19) when corrosion and strength matter more than galling; 17-4PH H950 or hardened 410 as the mating part for Nitronic 60 in stems and seats (no galling up to 345 MPa in the test); Stellite 6 or hardfacing when abrasive wear dominates; 316L when there is no metal-to-metal contact.
Nitronic 60: complete guide
What Nitronic 60 is
Nitronic 60 is a manganese-silicon-nitrogen austenitic stainless steel. Silicon (3.5 – 4.5%) and manganese (7.0 – 9.0%) reduce wear, galling and fretting, even in the annealed condition, making the alloy a lower-cost alternative to cobalt and high-nickel alloys for fighting wear. Nitrogen raises yield strength to ≈ 414 MPa annealed.
Galling resistance: test data
Unlubricated threshold galling stress (stress at which galling began), button on block, same material on both faces unless stated:
- 304 against 304: 14 MPa; 316 against 316: 14 MPa; 17-4PH H950 against 17-4PH H950: 14 MPa.
- Nitronic 60 against Nitronic 60: 345 MPa.
- Nitronic 60 against 304, 303, hardened 410, 440C or 17-4PH H950: no galling up to 345 MPa.
- Nitronic 60 against 316: 262 MPa; against annealed 430: 248 MPa.
The test was also run in liquid nitrogen (–196 °C), where the alloy keeps its galling resistance. Cold work raises strength but does not improve galling behavior.
Wear and cavitation
In unlubricated metal-to-metal wear (crossed cylinders, 415 rpm), the 304 against Nitronic 60 couple lost 6.0 mg per 1,000 cycles, versus 24.7 mg for 304 against 17-4PH (43 HRC); with 316, 4.3 mg versus 18.5 mg. Nitronic 60 against itself lost 2.8 mg. In cavitation erosion, taking Nitronic 60 as 1.00, 304 eroded 3.67 times faster, 316 3.70, aluminum bronze 3.00 and CA-6NM 6.80 (different test series).
Corrosion
General corrosion resistance lies between 304 and 316, but chloride pitting resistance is better than 316. In 6 months of quiet seawater, Nitronic 60 showed far better crevice corrosion resistance than 304 and slightly better than 316. When corrosion is the main requirement, Nitronic 50 (XM-19) is the safer choice.
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 60?
Per ASTM A276 / A479 (UNS S21800): C ≤ 0.10; Mn 7.0 – 9.0; Si 3.5 – 4.5; Cr 16.0 – 18.0; Ni 8.0 – 9.0; N 0.08 – 0.18.
Which standards cover Nitronic 60?
Bar and shapes: ASTM A276 / A479 S21800. Plate, sheet and strip: ASTM A240 S21800. Bar, forging and wire (aerospace): AMS 5848. Billet and bar for forging: ASTM A314. Wire: ASTM A580. Bolts and nuts: ASTM A193 B8S / A194 8S. Casting: ASTM A351 / A743 CF10SMnN. Pressure vessel: ASME Section VIII Div. 1 (UHA-23).
Up to what temperature can Nitronic 60 be used?
From cryogenic (–196 °C, where it keeps its galling resistance) to high temperature: oxidation resistance similar to 309 and good strength up to ≈ 980 °C (1,800 °F).
Which materials can replace Nitronic 60?
Nitronic 50 (XM-19) when corrosion and strength matter more than galling; 17-4PH H950 or hardened 410 as the mating part for Nitronic 60 in stems and seats (no galling up to 345 MPa in the test); Stellite 6 or hardfacing when abrasive wear dominates; 316L when there is no metal-to-metal contact.
What is galling?
It is adhesion and tearing of material between two metal surfaces sliding under load, typical of stainless against stainless. In the manufacturer's unlubricated test, 304 against 304 and 316 against 316 galled at 14 MPa; Nitronic 60 against Nitronic 60 only at 345 MPa.
Is Nitronic 60 magnetic?
No. Magnetic permeability in the annealed condition is 1.003.
What is the difference between Nitronic 50 and Nitronic 60?
Nitronic 50 (XM-19) is designed for corrosion resistance and strength (typical PREN ≈ 34, yield ≥ 380 MPa). Nitronic 60 trades some corrosion resistance for silicon and manganese, which give galling and wear resistance; its general corrosion resistance lies between 304 and 316.
Is there a Nitronic 80?
We found no commercial alloy with that name. The Nitronic family (Cleveland-Cliffs, formerly AK Steel/Armco) includes grades 19D, 30, 32, 33, 40, 50 and 60. For galling resistance use Nitronic 60; for corrosion resistance with high strength, Nitronic 50 (XM-19).
