Invar 36 Alloy Pipe (ASTM F1684 / FeNi36 / UNS K93600)

Source：http://www.zytcsteel.com Time：2026/8/25 16:12:27 View：

Invar 36 (also known as FeNi36, Nilo® 36, Alloy 36, or Chinese grade 4J36) is a nickel-iron low-expansion alloy containing approximately 36% nickel. Its most defining characteristic is an exceptionally low coefficient of thermal expansion (CTE) – approximately one-tenth that of carbon steel – which it maintains from cryogenic temperatures up to about +500°F (260°C).

Common grades of Invar exhibit a CTE of approximately 1.2 × 10⁻⁶ /°C (1.2 ppm/°C) between 20°C and 100°C, compared to 11–15 ppm/°C for ordinary steels.

ZYTC Alloy stocks and supplies a comprehensive range of Invar 36 products, including pipe, tube, bar, rod, cold-rolled sheet, hot-rolled plate, strip, and welding wire – all manufactured to the highest quality standards.

Chemical Composition

Weight %	Ni	Fe	C	Mn	P	S	Si	Cr	Mo	Co
Invar 36	35-38	Rem	0.10 max	0.06 max	0.025 max	0.025 max	0.35 max	0.50 max	0.50 max	1.0 max

Mechanical Properties

Material	Condition	Ultimate Tensile Strength		Yield Strength 0.2 %		Elongation (%)
		psi	MPa	psi	MPa
Invar 36	Annealed	71,000	490	35,000	240	42

Authoritative Industry Specifications & Standards

ZYTC Alloy’s Invar 36 alloy pipes comply with multiple global mainstream industrial, aerospace and military standards, fully meeting international procurement and certification requirements:

Core Standard: ASTM F1684
UNS Grade: K93600, K93601
Material Designation: FeNi36, NILO 36, Invar 36
German Standard: Werkstoff Nr. 1.3912
Plate & Strip Standards: ASTM B388, ASTM B753, DIN 1715
Military Specifications: MIL-S-16598, MIL-I-23011 CL 7

Core Material Performance

Near-Zero Thermal Expansion: Ultra-low expansion coefficient from cryogenic temperature up to 260°C (500°F), ensuring long-term dimensional stability of precision components.
Excellent Cryogenic Performance: No brittle failure at ultra-low temperatures, maintaining complete strength and toughness, ideal for liquefied gas storage and delivery systems.
High Structural Stability: Low thermal deformation, anti-fatigue and anti-creep properties, suitable for long-term stable operation of precision optical and measuring equipment.
Reliable Machinability: Balanced hardness and toughness, easy for precision cutting, drilling and secondary forming.

Precision Size Range & Tolerance Standard

ZYTC Alloy specializes in ultra-precision thin-wall Invar 36 tubes, supporting both standard industrial tolerance and ultra-tight precision tolerance customization to meet high-end precision assembly needs:

Basic Dimension Scope

Outer Diameter (OD): 0.25mm (0.010”) – 16.00mm (0.625”); maximum thin-wall tube OD up to 25.40mm (1.000”) available
Wall Thickness (WT): 0.05mm (0.002”) – 1.00mm (0.040”)
Straight Length: 1.00mm – 5000.00mm
Coil Length: 5m – 15m customized coiled tubes

Precision Tolerance Grade

Standard Tolerance: OD/ID ±0.03mm; Wall thickness ±10%
Tight Precision Tolerance: OD/ID ±0.015mm; Wall thickness ±3%

All tubes feature smooth inner and outer walls, uniform wall thickness, no burrs and no oxide scale, fully adapted for precision instrument assembly and ultra-precision processing.

Wide Product Portfolio

As a full-range Invar alloy supplier, ZYTC Alloy maintains sufficient stock of complete Invar 36 material series to support one-stop procurement:

Invar 36 Pipe & Tube (precision thin-wall tube / thick-wall tube)
Invar 36 Bar & Round Rod
Invar 36 Cold-Rolled Sheet & Hot-Rolled Plate
Invar 36 Welding Wire

Applications

With ultra-low expansion and cryogenic stability, Invar 36 alloy tubes are widely used in high-precision and extreme-environment industries worldwide:

Aerospace & Aircraft Systems: Aircraft control components, composite tooling molds and precision structural parts
Optical & Laser Industry: Laser equipment structural parts, optical instrument brackets and precision measuring benchmarks
Electronic & Radio Devices: High-stability electronic components and precision instrument structural parts
Cryogenic Engineering: Liquefied gas storage tanks, low-temperature delivery piping and cryogenic system components
Precision Metrology: Standard length gauges, thermostat rods and high-precision measuring device parts

ZYTC Alloy Supply Advantages

ZYTC Alloy focuses on the R&D and production of precision low-expansion alloys for many years. We have mature precision rolling and fine drawing processes for Invar 36 thin-wall tubes, which can stably achieve micron-level ultra-tolerance control. All products are strictly tested for thermal expansion coefficient, dimensional tolerance and surface quality before delivery, with complete MTR test reports and material traceability files.

We support small-batch prototype customization and mass bulk orders, providing professional size selection, tolerance scheme optimization and processing technical guidance for global customers, helping customers solve precision dimensional stability problems in high-end equipment manufacturing.

Contact Us

Contact ZYTC Alloy to get official Invar 36 datasheets, precision tolerance solutions, batch test reports and competitive ex-factory quotations.

📧 Email: dominic@zytc-steel.com
📲 WhatsApp: +86 13132148618

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