Overview

Nitronic 50 is a nitrogen-strengthened, high-manganese, molybdenum-bearing austenitic chromium-nickel stainless steel (nominally 22% chromium, 13% nickel, 5% manganese with molybdenum, niobium, vanadium and nitrogen — the "22-13-5" composition) that combines high strength with corrosion resistance superior to the standard molybdenum austenitic grades. This datasheet presents the material within the trade-name designation system.

Its room-temperature yield strength is about twice that of the 316/316L and 317/317L grades (and up to about three times in the cold-worked condition), achieved through nitrogen and manganese strengthening rather than through molybdenum alone. Its general and crevice corrosion resistance is superior to the 316/316L and 317/317L grades, with a Pitting Resistance Equivalent Number (PREN) above 34 — on a par with 2205-type duplex stainless steel. The high manganese and nitrogen stabilise the austenite so effectively that the alloy remains non-magnetic even after severe cold work or at sub-zero temperatures, and it retains good mechanical properties from cryogenic to elevated temperatures. As with most austenitic stainless steels, it can be susceptible to stress-corrosion cracking in hot chloride-bearing environments.

It is readily welded by conventional processes using a matching over-alloyed filler; autogenous high-power-density processes such as electron-beam and laser welding are approached with caution. Typical applications include fasteners, bolting and shafting, chains, pump and valve components, flanges, springs, marine hardware, petrochemical equipment and medical implants.

1. Physical Properties

Values per manufacturer / reference data, annealed condition.

2. Chemical Composition (wt %)

Limiting composition per ASTM A276 / AMS 5764.

Nominal: 22Cr-13Ni-5Mn with Mo, Nb, V and N. Nitrogen and manganese provide strength and austenite stability; molybdenum and nitrogen give the elevated pitting/crevice resistance (PREN > 34).

3. Mechanical Properties

Typical room-temperature properties, annealed condition.

Room-temperature yield strength is about twice that of 316/316L and 317/317L (up to three times when cold-worked), with good properties from cryogenic to elevated temperatures. Values are typical; confirm against the mill test certificate.

4. Corrosion Resistance

5. Heat Treatment

An austenitic stainless steel; it cannot be hardened by heat treatment. High strength comes from nitrogen, manganese, niobium and vanadium; strength can be raised further by cold work.

Solution Anneal about 1065 °C (1950 °F) gives adequate corrosion resistance with high strength for many applications; for as-welded service or very corrosive media, the 1121 °C (2050 °F) anneal is preferred. Follow with rapid cooling (water quench).

Material in the high-strength cold-worked condition is often specified for bolting and shafting, with a small compromise in corrosion resistance versus the annealed condition. Hot working is done at 1177–1204 °C (2150–2200 °F).

6. Weldability and Joining

Readily welded by conventional processes — gas-tungsten-arc, gas-metal-arc, shielded-metal-arc and submerged-arc — using a matching over-alloyed filler, Nitronic 50W. Caution is required with autogenous high-power-density processes such as electron-beam and laser welding, owing to low ferrite number and nitrogen outgassing.

No preheat required. Use matching over-alloyed filler to maintain strength and corrosion resistance.

7. Machinability and Fabrication

Machining Guidelines

Forming Processes

8. Applications

9. Available Product Forms and Standards

Nitrogen-strengthened 22-13-5 austenitic stainless steel. UNS S20910; AMS 5764; ASTM A276 / A240 / A182 / A193; NACE MR0175. Tradenames: Nitronic 50, Alloy 50, Fermonic 50.

10. Comparison with Related Alloys (Nitronic Trade-Name System)

Next：Alloy 50