AMS 5561 UNS S21900 Nitronic 40 (21-6-9) Seamless Tubing

ZYTC Alloy supplies AMS 5561 UNS S21900 Nitronic 40 (21-6-9) seamless & welded drawn tubing, featuring non-magnetic, ultra-cryogenic toughness and high strength for aerospace, cryogenic and nuclear applications.

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ZYTC Alloy, a professional Chinese manufacturer and supplier of high-performance aerospace-grade stainless steel tubular products, provides premium AMS 5561 UNS S21900 Nitronic 40 (21-6-9) seamless drawn tubing and welded & drawn tubing. As a nitrogen-strengthened austenitic stainless steel, Nitronic 40 delivers a unique combination of superior mechanical strength, extreme cryogenic toughness, excellent corrosion resistance and stable non-magnetic properties, serving critical applications in aerospace, cryogenic engineering, chemical processing, marine and nuclear industries worldwide.

The SAE AMS 5561 specification governs corrosion and heat-resistant Nitronic 40 tubing manufactured via seamless drawn or welded & drawn processes. Different from conventional 300-series stainless steels, Nitronic 40 achieves remarkable property enhancement through precise nitrogen and manganese alloying, overcoming the strength and toughness limitations of standard stainless grades while maintaining exceptional structural stability under ultra-low and aggressive high-temperature service conditions.

Chemical Composition

Element	Weight % (min)	Weight % (max)
Chromium (Cr)	19.0	21.5
Nickel (Ni)	5.5	7.5
Manganese (Mn)	8.0	10.0
Nitrogen (N)	0.15	0.40
Carbon (C)	–	0.08
Silicon (Si)	–	1.00
Phosphorus (P)	–	0.060
Sulfur (S)	–	0.030
Iron (Fe)	Balance	Balance

The high nitrogen and manganese content are the key differentiators. Nitrogen increases the austenite stability and provides solid-solution strengthening, while manganese replaces a portion of nickel to stabilize austenite and improve toughness at cryogenic temperatures.

Mechanical Properties

Condition	Tensile Strength (MPa)	Yield Strength 0.2% (MPa)	Elongation (% in 50mm)	Hardness (HRB)
Annealed (min)	621	345	35	–
Annealed (typical)	690 – 760	380 – 450	40 – 50	~90
Cold Worked / Hardened (min)	1034	827	20	–
Cold Worked (typical)	1117 – 1200	900 – 1000	20 – 30	~100 (HRB)

The cold-worked condition offers a yield strength exceeding 827 MPa—nearly double that of annealed 316 stainless steel—making Nitronic 40 ideal for high-pressure and load-bearing applications without requiring heavy-wall sections.

Physical Properties

Property	Value	Unit
Density	7.8	g/cm³ (0.282 lb/in³)
Melting Range	1400 – 1430	°C (2550 – 2600 °F)
Modulus of Elasticity	196	GPa (28.4 × 10⁶ psi)
Coefficient of Thermal Expansion (20–200°C)	16.0	×10⁻⁶ /°C
Thermal Conductivity (at 100°C)	14.4	W/m·K
Specific Heat (0–100°C)	500	J/kg·K
Electrical Resistivity	75	×10⁻⁸ ohm·m
Magnetic Permeability (after cold work)	< 1.005	μ (non-magnetic)

One of the most valuable attributes of Nitronic 40 is its stable austenitic structure. Unlike 304 or 301 stainless steels, which undergo strain-induced martensitic transformation and become magnetic after cold work, Nitronic 40 remains essentially non-magnetic even after severe cold reduction. This is critical for aerospace instrumentation and cryogenic systems where magnetic interference must be minimized.

Product Supply Capacity

As a professional Chinese specialty stainless steel manufacturer, ZYTC Alloy supplies full-spec AMS 5561 UNS S21900 Nitronic 40 seamless drawn tubing and welded & drawn tubing. All products are manufactured in strict accordance with AMS 5561 aerospace specifications, with precise dimensional tolerance, uniform microstructure and stable mechanical performance. Custom caliber, wall thickness, length and precision processing services are available. Each batch is equipped with complete mill test reports (MTR) and full material traceability, supporting third-party inspection.

Applications

Aerospace Industry
Cryogenic Engineering
Chemical & Petrochemical
Marine Engineering
Nuclear Industry
High-Performance Automotive

Manufacturing Advantages of ZYTC Alloy

ZYTC Alloy focuses on the production of aerospace-grade Nitronic series stainless steel tubular products. We adopt precision smelting, controlled hot/cold working and standardized heat treatment processes to ensure that AMS 5561 Nitronic 40 tubing features high strength, stable non-magnetic properties, extreme low-temperature toughness and excellent corrosion resistance. Our professional metallurgical team provides one-stop technical support including process guidance, welding suggestions and material application optimization for global industrial and aerospace clients.

Contact Us

Contact ZYTC Alloy to obtain official datasheets, inspection reports, stock information and customized quotations for AMS 5561 UNS S21900 Nitronic 40 seamless drawn tubing.

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