Project Description

 

Introduction

Nitronic 50, also known as Fermonic 50, is a high-strength austenitic stainless steel designated as ASTM XM-19, UNS S20910, and EN 1.3964. Developed originally by Armco Steel, it offers approximately twice the yield strength of 316 stainless steel while maintaining comparable corrosion resistance. The alloy is widely used in the oil & gas, marine engineering, chemical processing, aerospace, and medical device industries where high strength combined with excellent pitting resistance in chloride environments is required. Its nitrogen-strengthened austenitic matrix provides superior resistance to stress corrosion cracking and remains non-magnetic even after severe cold working, making it ideal for critical service in sour gas applications per NACE MR0175 / ISO 15156.

Nitronic 50 stainless steel product
Nitronic 50 / XM-19 Round Bar

Equivalent Grades & Standards

Standard / System Grade / Designation
ASTM XM-19 per ASTM A276, A479, A240, A182, A193, A194
AMS AMS 5764 (bar, wire, forgings), AMS 5842, AMS 5843
EN / DIN 1.3964 / X2CrNiMnMoNbN 21-15-3-1 per EN 10088-3, EN 10272
UNS S20910
Trademarks Nitronic 50 (Cleveland-Cliffs), Fermonic 50
NACE MR0175 / ISO 15156 for sour service
JIS No direct equivalent; closest SUS 316 or duplex 2205
GOST No direct equivalent; closest 08Kh21N6M2T

Typical Applications

Oil & Gas: valve stems, pump shafts, wellhead components, christmas tree parts, subsea bolting, downhole tooling.
Marine: propeller shafts, rudder stocks, fasteners, seawater pump impellers, mooring hardware.
Chemical Processing: agitator shafts, pressure vessel internals, heat exchanger components, filter housings.
Aerospace: high-strength fasteners, landing gear bushings, structural brackets.
Medical: orthopaedic implants, surgical instruments, dental fixtures.
Power Generation: turbine bolting, condenser tubing, nuclear reactor internals.

Its combination of high strength, non-magnetic properties, and chloride pitting resistance makes it a preferred choice where standard 316 falls short mechanically.

Supply Range

Form Dimensions
Round Bar Dia. 6 mm – 500 mm (0.25″ – 20″)
Flat Bar Thk. 3–80 mm × W 10–350 mm
Plate / Sheet Thk. 0.5–100 mm × W up to 2500 mm
Seamless Tube OD 6–300 mm × WT 0.8–30 mm
Wire Dia. 0.1–12 mm (0.004″–0.47″)
Forgings OD up to 2000 mm; weight up to 5000 kg

Chemical Composition

Per ASTM A276 / A479 (weight %):

C Mn Si P S Cr Ni Mo Nb N Fe
≤0.06 4.0–6.0 ≤1.00 ≤0.040 ≤0.030 20.5–23.5 11.5–13.5 1.5–3.0 0.1–0.3 0.2–0.4 Bal.

High nitrogen and molybdenum contents provide the alloy’s distinctive pitting resistance and elevated strength in the annealed condition.

Mechanical Properties

Condition Tensile Strength (MPa) Yield Strength 0.2% (MPa) Elongation (%) Hardness (HRB)
Annealed (ASTM A276) ≥690 (100 ksi) ≥380 (55 ksi) ≥35 ≤96
Cold Worked (typical) 860–1000 620–860 15–25 25–38 HRC
AMS 5764 (solution annealed) ≥690 ≥380 ≥35 ≤96

Annealing is performed at 1065–1120°C followed by water quenching. The alloy remains austenitic and non-magnetic (relative permeability ≤1.02) in all conditions. Impact toughness at cryogenic temperatures is excellent, with Charpy V-notch values typically exceeding 100 J at -196°C.