Name: Invar 36
Brand: Invar

Material Overview

Invar 36 material profile

A concise grade introduction for buyers who need to confirm composition, properties, standards, available forms and suitable applications before sending an inquiry.

Engineering profile

Invar 36 is an iron-nickel controlled-expansion alloy containing approximately 36% nickel. Its thermal expansion rate is approximately one-tenth that of carbon steel at temperatures up to about 204 °C, making it suitable for components that must maintain stable dimensions during temperature changes. Invar 36 is widely used for aerospace tooling, composite forming molds, cryogenic equipment, optical and laser systems, semiconductor components, metrology instruments, precision measuring devices, electronic components and assemblies matched to low-expansion materials.

Technical data on this page is for material selection reference. Final acceptance values should be confirmed by the purchase standard, heat treatment condition, product form, size and material test certificate.

Chemical Composition

Invar 36 composition range

The following table shows common limiting composition values for Alloy 625 / UNS N06625. Actual product chemistry is reported by heat on the material test certificate.

Element	Symbol	Typical Requirement (%)	Role in Invar 36
Nickel	Ni	35.0-37.0	Produces the characteristic low-expansion behavior of the alloy.
Iron	Fe	Balance	Forms the base matrix and contributes to the alloy’s magnetic behavior.
Manganese	Mn	0.60 max	Supports melting practice and metallurgical control.
Silicon	Si	0.35 max	Controlled as a minor deoxidizing element.
Carbon	C	0.10 max	Controlled to maintain workability and dimensional performance.
Chromium	Cr	0.50 max	Controlled residual element.
Molybdenum	Mo	0.50 max	Controlled residual element.
Copper	Cu	0.50 max	Controlled residual element.
Phosphorus	P	0.025 max	Controlled impurity for processing and product quality.
Sulfur	S	0.025 max	Controlled impurity unless a free-machining grade is specified.

Physical Properties

Key physical and thermal data

These values help customers compare density, thermal behavior, magnetic response and conductivity during early material selection.

Property	Metric Value	Imperial / Notes	Condition
Density	Approx. 8.11 g/cm3	Approx. 0.293 lb/in3	Room temperature
Melting Point	Approx. 1430 °C	Approx. 2605 °F	Typical value
Curie Temperature	Approx. 230 °C	Approx. 446 °F	Chemistry and condition dependent
Thermal Conductivity	Approx. 10 W/m·K	Approx. 69 Btu·in/ft2·h·°F	Room temperature
Specific Heat	Approx. 515 J/kg·°C	Approx. 0.123 Btu/lb·°F	Room temperature
Electrical Resistivity	Approx. 0.82 µΩ·m	Approx. 82 µΩ·cm	Room temperature
Modulus of Elasticity	Approx. 141 GPa	Approx. 20.5 x 10³ ksi	Annealed, room temperature
Mean CTE, 21 to -100 °C	Approx. 1.26 µm/m·°C	Approx. 0.70 µin/in·°F	Representative manufacturer data
Mean CTE, 21-100 °C	Approx. 1.44 µm/m·°C	Approx. 0.80 µin/in·°F	Representative manufacturer data
Mean CTE, 21-150 °C	Approx. 1.98 µm/m·°C	Approx. 1.10 µin/in·°F	Representative manufacturer data
Mean CTE, 21-200 °C	Approx. 2.52 µm/m·°C	Approx. 1.40 µin/in·°F	Representative manufacturer data
Mean CTE, 21-250 °C	Approx. 3.42 µm/m·°C	Approx. 1.90 µin/in·°F	Representative manufacturer data

Mechanical Properties

Room-temperature mechanical properties

Mechanical properties vary with product form, size, processing route and heat treatment. The table below summarizes commonly referenced nominal values for material selection.

Product Form / Condition	Tensile Strength	Yield Strength, 0.2%	Elongation	Hardness
Annealed bar and strip – typical	Approx. 448 MPa / 65 ksi	Approx. 276 MPa / 40 ksi	Approx. 35%	Approx. 70 HRB
Cold drawn bar – typical	Approx. 621 MPa / 90 ksi	Approx. 483 MPa / 70 ksi	Approx. 20%	Approx. 90 HRB
Cold rolled strip – typical	Approx. 717 MPa / 104 ksi	Approx. 679 MPa / 98.5 ksi	Approx. 5.5%	Approx. 98 HRB
Finished precision component	By product specification	By product specification	By specification	By specification

For pressure equipment, aerospace parts or project-specific acceptance, use the minimum requirements in the specified ASTM, ASME, AMS, EN or customer drawing rather than nominal values.

Standards & Specifications

Common Invar 36 standards by product form

YSN128 can quote Alloy 625 products according to ASTM, ASME, AMS, EN, DIN, ISO or customer drawing requirements. Certificate scope can be matched to the purchase order.

Scope	Common Standard / Requirement	Application	Buyer Note
Thermostat Component Alloy	ASTM B753-07(2024), Alloy T36	Sheet and strip used as components in bonded thermostat metal	This active standard is application-specific and does not cover every Invar 36 product form.
Controlled-Expansion Material	ASTM F1684-06(2021), withdrawn 2024	Legacy requirements for UNS K93603 wire, rod, bar, strip, sheet and tubing	Use only when accepted by the purchaser or retained by a project specification.
European Designation	W.Nr. 1.3912 / FeNi36	European identification for 36% nickel controlled-expansion alloy	Confirm the required national or customer material specification.
Thermal Expansion Testing	ASTM E228-22	Linear thermal expansion testing by push-rod dilatometer	Specify the test interval, specimen direction, thermal history and acceptance value.
Tensile Testing	ASTM E8/E8M-25	Room-temperature tensile strength, yield strength and elongation testing	Results depend on product form, cold work, orientation and heat treatment.
Custom Precision Products	Customer drawing or OEM material specification	Tooling, optical structures, cryogenic components and machined assemblies	Customer requirements should define CTE, stabilization treatment and dimensional tolerances.
Inspection Documents	EN 10204 3.1 or agreed mill certificate	Chemical analysis, mechanical testing, heat treatment and traceability	Confirm certificate and additional testing requirements before ordering.

Available Product Forms

Invar 36 supply range

Review available product forms, size ranges, standards and delivery options for this alloy.

Form	Common Size Range	Delivery Condition	Typical Applications	Page Link
Pipe & Tube	Precision small-bore to large drawing-based dimensions	Seamless, welded, cold drawn, annealed or stress relieved	Cryogenic lines, precision supports and dimensionally stable tubular assemblies	View Pipe & Tube
Round Bar	Diameter 3-300 mm, larger custom forgings available	Hot rolled, forged, annealed, peeled, ground or cold drawn	Optical mounts, measuring components, shafts and machined parts	View Round Bar
Sheet & Plate	Thickness 0.5-100 mm, custom widths and lengths	Hot rolled, cold rolled, annealed or precision flattened	Composite tooling, molds, instrument frames and aerospace structures	View Sheet & Plate
Strip & Foil	Thickness 0.02-3 mm, slit widths to specification	Cold rolled, annealed, bright finished or tension leveled	Thermostat components, precision spacers and electronic assemblies	View Strip & Foil
Wire	Diameter 0.1-12 mm, coil, spool or straight length	Cold drawn, annealed, bright finished or stress relieved	Precision wire parts, measuring devices and electronic components	View Wire
Fasteners	Standard-style and custom drawing dimensions	Machined or thread rolled, annealed or stress relieved	Low-expansion tooling, optical equipment and precision assemblies	View Fasteners
Fittings	Drawing-based elbows, tees, reducers and special connectors	Machined, formed or welded with agreed heat treatment	Precision tubular systems and cryogenic assemblies	View Fittings
Flanges	Custom diameters, thicknesses and drilling patterns	Forged or plate-cut, machined and dimensionally stabilized	Vacuum systems, optical chambers and instrument interfaces	View Flanges
Forgings	Rings, discs, blocks, shafts and drawing-based components	Forged, annealed, rough machined or finish machined	Aerospace tooling, molds, support rings and precision structures	View Forgings
Welding Wire	Diameter 0.8-4.0 mm or project-specific dimensions	Clean bright finish with controlled matching chemistry	Qualified joining and repair of Invar 36 assemblies	View Welding Wire

Material Selection Guide

When to consider Invar 36

This guide helps buyers connect service conditions with the typical advantage of Alloy 625. Final selection should consider medium concentration, temperature, pressure, fabrication, availability and budget.

Service Requirement	Recommended Alloy	Reason for Selection	Buyer Note
General low expansion from cryogenic to moderate temperatures	Invar 36	Provides stable dimensions across a useful temperature range with broad commercial availability.	Define the complete operating range and maximum permitted expansion.
Minimum expansion close to room temperature	Super Invar 32-5	Can provide lower room-temperature expansion than conventional Invar 36.	Its CTE is especially sensitive to chemistry, heat treatment and thermal history.
Composite forming tools and molds	Invar 36	Its low expansion helps tooling remain dimensionally compatible with composite structures.	Specify plate quality, weld procedure, stress relief and dimensional stabilization.
Glass-to-metal or ceramic hermetic sealing	Kovar or another sealing alloy	Its expansion curve is designed to match selected glasses and ceramics during sealing.	Select the alloy according to the exact glass composition and sealing cycle.
Expansion matching selected electronic glass	Invar 42	Its higher nickel content provides a different expansion curve suited to selected glass and electronic applications.	Compare expansion over the complete assembly temperature range.
Easy machining of bar components	Free-machining Invar grade	Controlled additions can improve chip formation and machining productivity.	Confirm that the modified chemistry and CTE remain acceptable for the application.

Why Choose Us

Supply and quality support for Invar 36

For ranking traffic, buyers need more than a data sheet. This section gives clear trust signals for procurement, engineering and quality teams.

STASTM / ASME / AMS / EN

Quotation can be matched to project standards and product form specifications.

MTEN10204 3.1 MTC

Heat number, chemistry, mechanical properties and inspection records can be supplied.

QCPMI & Inspection

PMI, UT, dimensional inspection, visual inspection and packing check are available.

CSCustom Size

Cutting, machining allowance, rough machining and drawing-based supply can be arranged.

EPExport Packing

Wooden case, bundle, waterproof protection and international shipping documents.

RFFast Technical Reply

Send grade, size, standard, quantity and destination for a practical quotation route.

Related Nickel Alloys

Compare nearby grades and product forms

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Invar Super Invar 32-5

Super Invar 32-5 is an iron-nickel-cobalt controlled-expansion alloy developed for exceptionally low dimensional change around room temperature. Identified as UNS K93500, it provides lower thermal...

Invar Invar 42

Invar 42, also known as Alloy 42 or NILO 42, is a controlled-expansion iron-nickel alloy developed to provide a predictable thermal expansion rate over a...

FAQ

Invar 36 questions from buyers

Find practical answers about procurement, standards, fabrication and industrial applications.

Invar 36 is used for aerospace and composite tooling, molds and dies, cryogenic equipment, optical and laser systems, metrology instruments, precision measuring devices, semiconductor components, electronic assemblies and parts requiring minimal dimensional change.

Invar 36 may be identified as UNS K93600, K93601 or K93603 depending on the producer and governing specification. The purchase order should state the required chemistry, product form and applicable specification rather than relying only on the trade name.

Invar 36 contains approximately 36% nickel, while Super Invar 32-5 contains approximately 32% nickel and 5.5% cobalt. Super Invar can provide lower expansion close to room temperature, while Invar 36 offers a broader history of use and generally wider product availability.

A representative mean CTE from approximately 21 to 100 °C is about 1.44 µm/m·°C. The value increases over wider or higher temperature intervals and varies with chemistry, cold work, annealing, residual stress and thermal history.

YSN128 can quote plate, sheet, strip, round bar, rod, wire, precision tube, forgings and drawing-based fasteners, fittings and flanges. Custom cutting, machining allowance, heat treatment and dimensional stabilization can be discussed.

ASTM B753-07(2024) includes Alloy T36 for thermostat component applications. ASTM F1684 historically covered UNS K93603 but was withdrawn in 2024. ASTM E228 may be used for thermal expansion testing and ASTM E8/E8M for tensile testing.

Yes. Invar 36 can be welded using qualified GTAW, GMAW or other suitable processes with compatible filler chemistry. Weld shrinkage and residual stress can affect dimensional accuracy, so precision assemblies may require stress relief, thermal stabilization and final dimensional inspection.

Please send the grade or UNS number, product form, dimensions, quantity, operating temperature range, required CTE, delivery condition, heat treatment, dimensional tolerances, inspection requirements and certificate type. Drawings should be supplied for custom or precision-machined components.

Invar 36