Nitronic 50 and AISI 316L are both austenitic, non-magnetic stainless steels. Nitronic 50 was developed to close two of the weak points of 316L at once: low yield strength and pitting corrosion in chlorides.
Nitrogen and manganese
According to our datasheets, Nitronic 50 has chromium at 20.5–23.5%, nickel at 11.5–13.5% and molybdenum at 1.5–3.0%. So far it resembles 316L. Two elements make the difference: 4.0–6.0% manganese and 0.20–0.40% nitrogen.
Nitrogen is the strongest solid solution strengthener in austenitic stainless steels; manganese raises the solubility of nitrogen in the steel and so makes it possible to hold nitrogen at such a high level. The result is a yield strength of 380–485 MPa even in the solution annealed condition — more than twice the 170 MPa of 316L. In the cold worked condition the yield rises above 690 MPa.
The second effect of nitrogen is in corrosion: in the PREN formula that measures pitting resistance, the coefficient of nitrogen is 16 — that is, its effect is sixteen times that of chromium. The combination of high chromium + molybdenum + nitrogen gives Nitronic 50 chloride resistance markedly above that of 316L.
A third advantage: the non-magnetic property is retained after cold forming as well — while 316L becomes partly magnetic when cold worked, Nitronic 50 stays stable.
Comparison in numbers
| PROPERTY | Nitronic 50 | AISI 316L |
|---|---|---|
| Chromium (Cr) | 20.5 – 23.5% | 16.0 – 18.0% |
| Nickel (Ni) | 11.5 – 13.5% | 10.0 – 14.0% |
| Molybdenum (Mo) | 1.5 – 3.0% | 2.0 – 3.0% |
| Manganese (Mn) | 4.0 – 6.0% | max 2.00% |
| Nitrogen (N) | 0.20 – 0.40% | max 0.10% |
| Carbon (C) | max 0.06% | max 0.03% |
| Silicon (Si) | max 1.0% | max 0.75% |
| Tensile strength (solution annealed) | 690 – 760 MPa | 485 MPa |
| Yield strength Rp0.2 (solution annealed) | 380 – 485 MPa | 170 MPa |
| Tensile strength (cold worked) | above 1000 MPa | — |
| Yield strength (cold worked) | above 690 MPa | — |
| Elongation | 35 – 45% | 40% |
| Hardness | ~230 HB | max 217 HB |
| Density | 7.9 g/cm³ | 8.00 g/cm³ |
| Service temperature | structural stability up to 870 °C | — |
| UNS | S20910 | S31603 |
| W.Nr (DIN/EN) | 1.3964 | 1.4404 |
| AMS | 5764 | 5653 · 5507 |
Values are taken from our product datasheets; section thickness and the applied heat treatment regime change the result.
Which one, and when?
AISI 316L is sufficient — food and pharmaceutical pipework, welded tanks and pipes, general process equipment, architectural applications. It is easy to source in every form, far lower in cost and comfortable to machine.
Nitronic 50 is required — pump and valve shafts, seawater equipment, offshore fasteners, downhole components, non-magnetic high-strength parts (for example drilling measurement equipment housings). If the specification calls out AMS 5764, 316L is not an acceptable substitute.
Note: the high strength of Nitronic 50 makes it harder to machine; a low cutting speed and rigid clamping are required.
Alternatives
For duplex solutions in the same strength class, see our AISI 316L – Duplex 318 comparison; for higher corrosion resistance, our AISI 316L – 904L article.
Technical datasheets
Nitronic 50 — chemical composition, mechanical values, standard equivalents
AISI 316L — chemical composition, mechanical values, standard equivalents
Both grades are supplied to order in round bar, flat bar, plate, sheet, pipe and forged forms. Contact us for a quotation.