Nitronic 60 is a nitrogen-strengthened austenitic stainless steel built for a single, demanding purpose: to survive metal-on-metal contact where ordinary stainless grades would seize, gall, and tear themselves apart. Known formally as UNS S21800 and also referred to as Alloy 218, it has quietly become a default choice wherever two stainless surfaces have to slide, rotate, or thread against one another under load. This guide walks through what the alloy is made of, how it behaves, why it forges so well, and where it earns its place in critical hardware.
Unlike the familiar 300-series grades that lean on nickel and chromium, Nitronic 60 takes a different metallurgical route. It deliberately replaces a chunk of nickel with manganese and adds an unusually high level of silicon, then locks in extra strength using nitrogen rather than carbon. The result is a stainless steel that is roughly twice as strong as 304 in the annealed condition while shrugging off the galling and wear that plague conventional austenitics.
Section 01What Nitronic 60 Actually Is
"Nitronic" refers to a family of high-performance austenitic stainless steels strengthened with nitrogen. Within that family, the "60" grade was engineered specifically for wear and galling resistance rather than for cryogenic toughness or extreme corrosion performance. Its identity rests on three deliberate composition choices: high manganese, high silicon, and a controlled nitrogen addition.
That recipe matters because it changes how the surface behaves under friction. When two metal parts rub together, microscopic high points weld momentarily, then rip apart — the phenomenon engineers call galling. Standard stainless steels are notoriously prone to it. The silicon-rich surface chemistry of S21800 interrupts that weld-and-tear cycle, which is why it ends up in valve stems, fasteners, pins, and bushings that have to move without seizing.
Section 02Chemical Composition
The composition is where this alloy departs most sharply from a grade like 304 or 316. The elevated silicon and manganese are not incidental — they are the working ingredients behind the wear performance. Nitrogen, meanwhile, does the job that carbon does in many steels, but without the risk of sensitization that carbon brings to stainless grades.
| Element | Range | Role |
|---|---|---|
| Chromium | 16.0 – 18.0 | Corrosion resistance, passive film |
| Manganese | 7.0 – 9.0 | Austenite stability, work-hardening |
| Nickel | 8.0 – 9.0 | Austenite former, toughness |
| Silicon | 3.5 – 4.5 | Galling & wear resistance |
| Nitrogen | 0.08 – 0.18 | Solid-solution strengthening |
| Carbon | 0.10 max | Kept low to avoid sensitization |
| Iron | Balance | Base |
That ~4% silicon figure is the headline. Most stainless steels keep silicon under 1%; here it is several times higher, deliberately driving a surface behavior that the rest of the family cannot match.
Section 03Mechanical Properties
In the annealed condition Nitronic 60 delivers yield strength roughly double that of 304 stainless, and it work-hardens aggressively. Combined with good ductility, that makes it a structurally capable material rather than just a surface-treatment alternative. The values below are representative published figures for annealed bar and forged stock; exact results depend on section size and processing and should be confirmed against the mill test report for a given lot.
| Property | Typical value |
|---|---|
| 0.2% yield strength | 50 ksi (345 MPa) |
| Ultimate tensile strength | 100 ksi (690 MPa) |
| Elongation in 2 in. | 35% |
| Hardness | ~95 HRB |
| Density | 0.279 lb/in³ (7.62 g/cm³) |
| Structure | Fully austenitic, non-magnetic |
Section 04Why Nitronic 60 Resists Galling
Galling resistance is the reason most engineers reach for this alloy, so it is worth understanding the mechanism rather than treating it as a spec-sheet bullet. When two austenitic stainless surfaces slide under pressure, the soft, ductile asperities cold-weld and then shear, transferring material and chewing up both faces. The high silicon content in S21800 promotes a hard, stable surface layer that resists that adhesive transfer.
The practical payoff is significant: a Nitronic 60 fastener can often be run against another Nitronic 60 surface without anti-seize compound and still come apart cleanly. That self-mating capability is rare in stainless steel and is precisely why the alloy is favored for threaded and sliding hardware.
- Self-mating — performs well against itself, unlike 304/316 which gall readily.
- Holds up hot — galling resistance persists at elevated temperatures where many wear materials fade.
- No coating dependence — the resistance is inherent to the bulk chemistry, not a surface treatment that can wear away.
Section 05Corrosion Behavior
Nitronic 60 offers corrosion resistance comparable to 304 and, in many environments, approaching 316 — while leaving those grades far behind on wear. It performs well in oxidizing conditions, resists chloride stress-corrosion cracking better than the standard austenitics, and holds up in marine and seawater service. That combination of decent corrosion resistance plus exceptional wear is what makes it useful in pumps and valves handling aggressive media.
Section 06The Forging Process
Forging is where Nitronic 60 components gain much of their performance. The alloy is typically melted by argon-oxygen decarburization (AOD) or vacuum induction melting, often followed by remelting for cleaner, more homogeneous stock. From that billet, controlled heat and pressure refine the grain structure and align the metal flow lines with the geometry of the part.
This grain refinement is not cosmetic. Properly forged S21800 shows improved fatigue resistance, toughness, and directional strength compared with bar that is simply machined to shape. For rings, flanges, shafts, sleeves, and disks that see cyclic or impact loading, that difference can decide service life. Jiangsu Liangyi Co., Ltd. produces a full range of Nitronic 60 forged parts — rings, flanges, round bars, shafts, sleeves, bushings, tube sheets, and disks — to customer drawings and specifications.
From billet to finished forging
- Melting — AOD or vacuum induction melt, with optional vacuum-arc or electroslag remelting for cleanliness.
- Heating — billet brought to forging temperature to ensure full plasticity.
- Forging — open-die, closed-die, or ring-rolling to develop grain flow along the part.
- Heat treatment — solution anneal and quench to restore the optimum microstructure.
- Finishing — machining, testing, and inspection to the governing customer specification.
Section 07Heat Treatment
The standard treatment for Nitronic 60 is a solution anneal at roughly 1900–2050 °F (1040–1120 °C) followed by a rapid water quench. The anneal dissolves precipitates and resets the fully austenitic structure; the quench locks that structure in and preserves the alloy's corrosion and toughness properties. Because the grade relies on nitrogen rather than carbon for strength, it does not respond to conventional hardening heat treatments the way martensitic stainless grades do — strength comes from composition and cold work, not from quench-and-temper.
Section 08Where Nitronic 60 Is Used
The alloy's mix of wear resistance, strength, and corrosion tolerance places it across several demanding industries. The common thread is always moving or loaded contact in a hostile environment.
| Sector | Typical components |
|---|---|
| Valves & flow control | Valve stems, seats, trim, gate-valve internals |
| Fastening | Bolts, nuts, screws, pins, threaded hardware |
| Pumps | Wear rings, lobes, shafts, sleeves, bushings |
| Marine & offshore | Seawater pump parts, ballast-system valves, subsea hardware |
| Aerospace & defense | Bushings, bearing components, structural fittings |
| Construction | Bridge pins and other critical wear-prone fittings |
In each of these, an engineer could in principle specify a cheaper stainless — but the cost of a galled valve stem or a seized fastener in service almost always dwarfs the material premium.
Section 09How to Specify Nitronic 60 Forged Components
Getting the right forging starts with a clear specification. At minimum, a request should capture the governing material specification, the form and dimensions, the required heat treatment condition, and any testing or certification the application demands.
- Form & geometry — ring, flange, shaft, disk, sleeve, bushing, tube sheet, or custom drawing.
- Standard & grade — confirm UNS S21800 and the applicable material specification (for example ASTM A276 or SAE AMS 5764).
- Condition — solution-annealed and water-quenched is standard for most forgings.
- Testing & documentation — mechanical testing, NDT, and a mill test report (MTR) documenting conformance, as required.
- Tolerances & finish — machining allowances and surface requirements.
Need S21800 Forgings Made to Print?
Jiangsu Liangyi Co., Ltd. manufactures UNS S21800 forgings to your specification, with material supplied in accordance with customer-specified standards and conformance documented by a mill test report. See the full product range and request a quote on our product page.
View Nitronic 60 Forged PartsSection 10Frequently Asked Questions
Is Nitronic 60 the same as UNS S21800?
Yes. Nitronic 60 is a trade name; UNS S21800 is its Unified Numbering System designation. The alloy is also referred to as Alloy 218. All three refer to the same manganese- and silicon-rich, nitrogen-strengthened austenitic stainless steel.
How does Nitronic 60 compare to 316 stainless steel?
Nitronic 60 has roughly double the yield strength of 316 and dramatically better galling and wear resistance, with comparable general corrosion performance in many environments. 316 may still win on pure pitting resistance in some chloride settings, but it galls readily where Nitronic 60 does not.
Is Nitronic 60 magnetic?
No. In the annealed condition it is fully austenitic and essentially non-magnetic, though heavy cold work can induce a slight magnetic response, as with other austenitic grades.
Can Nitronic 60 be welded?
Yes, it has good weldability using standard austenitic procedures. Matching filler is available; following correct heat-input and post-weld practices preserves its corrosion and mechanical properties.
Why choose a forged Nitronic 60 part over machined bar?
Forging refines and aligns the grain structure with the component geometry, improving fatigue strength, toughness, and directional properties — valuable for parts under cyclic or impact loading such as shafts, rings, and flanges.
What standards apply to Nitronic 60 forgings?
The S21800 alloy is referenced in material specifications such as ASTM A276 and SAE AMS 5764. Material is typically supplied solution-annealed and water-quenched, with conformance to a customer-specified standard documented per order by a mill test report (MTR).
This guide is provided for general engineering reference only and does not constitute a warranty of properties or fitness for a particular purpose. Always confirm exact property values, standards, and material suitability against current mill certifications and the requirements of your specific application.
Nitronic® is a registered trademark of Cleveland-Cliffs Steel Corp. (successor to AK Steel). Jiangsu Liangyi Co., Ltd. is an independent manufacturer and is not affiliated with, authorized by, endorsed by, or sponsored by the trademark owner. The name "Nitronic 60" is used solely to identify the UNS S21800 alloy that we supply.