Nitronic / UNS S21800
Nitronic® 60 is a silicon- and manganese-alloyed austenitic stainless steel with outstanding resistance to galling and wear, often used to replace cobalt alloys in sliding and seating parts.
- UNS S21800
- Spec ASTM A240
- Density 7.62 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S21800 |
| Also known as | S21800, Alloy 218 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | — | 0.10 |
| Mn | 7.0 | 9.0 |
| P | — | 0.060 |
| S | — | 0.030 |
| Si | 3.5 | 4.5 |
| Cr | 16.0 | 18.0 |
| Ni | 8.0 | 9.0 |
| N | 0.08 | 0.18 |
| Fe | Bal. | — |
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength (min) | 655 MPa (95.0 ksi) |
| Yield strength, 0.2% offset (min) | 345 MPa (50.0 ksi) |
| Elongation in 50 mm (min) | 35 % |
| Hardness | 241 HB max |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.62 g/cm³ | 0.275 lb/in³ |
| Magnetic response | Non-magnetic | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets & plates | ASTM A240 / ASME SA240 | 0.3 mm – 6 mm |
| Bars & rods | ASTM A276, A479 | 3 mm – 500 mm |
| Flanges & forgings | ASTM A182 (F XM-19 for Nitronic 50) | 1/2" – 48" NB (larger on request) |
Corrosion & temperature resistance
Nitronic 50 resists pitting, crevice corrosion and seawater better than 316/317; Nitronic 60 offers corrosion resistance between 304 and 316 with outstanding galling resistance.
Applications
Nitronic® 60: Valve seats, wear plates, fasteners, pins. Marine shafting, pump shafts, valve stems and seats, fasteners, wear plates and chemical process components.
Nitronic® 60 vs Nitronic® 50
| Nitronic® 60 | Nitronic® 50 | |
|---|---|---|
| UNS | S21800 | S20910 |
| Key property | Best galling resistance of stainless | 2× yield of 316, better corrosion |
| Typical use | Valve seats, wear plates, fasteners, pins | Marine shafts, pump shafts, valve stems |
| Cr (wt %) | 16.0–18.0 | 20.5–23.5 |
| Ni (wt %) | 8.0–9.0 | 11.5–13.5 |
| Mo (wt %) | — | 1.50–3.00 |
| C (wt %) | ≤ 0.10 | ≤ 0.06 |
| Tensile / yield (min, MPa) | 655 / 345 | 690 / 380 |
Frequently asked questions
What is the UNS number of Nitronic® 60?
Nitronic® 60 is designated UNS S21800.
What is Nitronic® 60 used for?
Best galling resistance of stainless. Typical uses: valve seats, wear plates, fasteners, pins.
Is Nitronic® 60 magnetic?
Non-magnetic.
In which forms can I buy Nitronic® 60 from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Round Bars & Rods, Fasteners. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with Nitronic® 60?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between Nitronic® 60 and Nitronic® 50?
Nitronic® 60: best galling resistance of stainless. Nitronic® 50: 2× yield of 316, better corrosion. See the comparison table on this page.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
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