Name: Invar 42
Brand: Invar

Material Overview

Invar 42 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 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 defined temperature range. Its expansion characteristics make it suitable for matching selected soft glasses, ceramics and semiconductor materials in hermetic seals and electronic packages. Typical applications include integrated-circuit lead frames, glass-to-metal seals, feedthroughs, relay parts, vacuum components, electronic housings, lamp lead-in assemblies and precision components where dimensional compatibility during temperature changes is important.

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 42 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	Nominal / Common Requirement	Role in Invar 42
Nickel	Ni	Approx. 41.0-42.0	Controls the characteristic thermal expansion behavior of the iron-nickel matrix.
Iron	Fe	Balance	Forms the base of the controlled-expansion alloy.
Carbon	C	0.05 max	Restricted to support ductility, forming and sealing performance.
Manganese	Mn	0.40 max	Controlled minor addition used in melting and deoxidation.
Silicon	Si	0.20 max	Controlled for surface quality, oxidation behavior and glass sealing.
Other Elements	–	Controlled residuals	Residual elements are limited according to the producer or purchaser specification.

Alloy 42 chemistry varies slightly among producer specifications and regional designations. The required nickel range and residual-element limits should be stated in the purchase order, especially for glass sealing or semiconductor applications.

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 Value	Condition / Notes
Density	8.11 g/cm3	0.293 lb/in3	Room temperature
Melting Point	Approx. 1435 °C	Approx. 2615 °F	Typical value
Thermal Conductivity	10.5 W/m·°C	72.8 Btu·in/ft²·h·°F	Approx. 20 °C
Electrical Resistivity	0.61 µΩ·m	Approx. 367 ohm-cmil/ft	Approx. 20 °C
Modulus of Elasticity	Approx. 150 GPa	Approx. 21.8 x 10³ ksi	Room-temperature typical value
Mean Coefficient of Thermal Expansion	Approx. 5.3 µm/m·°C	Approx. 2.9 x 10^-6 in/in·°F	Mean value from 20 to 300 °C
Mean Expansion, 20-400 °C	Approx. 6.2 µm/m·°C	Approx. 3.4 x 10^-6 in/in·°F	Typical value; heat treatment and chemistry dependent
Thermal-Expansion Inflection Point	Approx. 370 °C	Approx. 700 °F	Expansion behavior changes above this region

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 / Notes
Hot-rolled annealed bar at 20 °C	Approx. 490 MPa (71 ksi)	Approx. 250 MPa (36 ksi)	Approx. 43%	Representative producer data; reduction of area approx. 72%
Hot-rolled annealed bar at 100 °C	Approx. 450 MPa (65 ksi)	Approx. 210 MPa (30 ksi)	Approx. 43%	Typical elevated-temperature value
Hot-rolled annealed bar at 300 °C	Approx. 410 MPa (59 ksi)	Approx. 110 MPa (16 ksi)	Approx. 44%	Typical elevated-temperature value
Sheet and strip – annealed	Specification dependent	Specification dependent	High ductility for forming	Approx. 140 HV max typical
Sheet and strip – full hard	Processing dependent	Processing dependent	Reduced from annealed condition	Approx. 240 HV min typical
Wire and precision strip	Temper dependent	Temper dependent	Temper dependent	Specify annealed, quarter-hard, half-hard or full-hard condition
Machined or formed sealing parts	Final-process dependent	Final-process dependent	Final-process dependent	Thermal expansion and surface condition normally govern acceptance

Mechanical properties are representative and secondary to thermal-expansion performance for most Alloy 42 applications. Final acceptance should be based on the purchaser specification, product form, temper, dimensions, thermal treatment, expansion test results and material test certificate.

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 42 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.

Product / Requirement	Common Standard	Current Status / Use	Certificate / Inspection
Sheet, Strip, Rod, Bar, Tube and Wire	ASTM F30	Withdrawn in 2024 without replacement; use only as a legacy or contractually specified sealing-alloy standard.	Chemistry, temper, grain size, surface finish and thermal-expansion results as specified
Sheet and Strip for Thermostat Components	ASTM B753	Active standard within its thermostat-component scope; confirm alloy designation and current edition.	Chemistry, dimensions, temper and thermal-response testing as required
Dumet and Lamp Lead-In Wire	ASTM F29	Withdrawn in 2024; use only when retained by an existing drawing or customer specification.	Core chemistry, cladding, dimensions, surface condition and seal testing
European Material Designation	W.Nr. 1.3917 / FeNi42	Use the purchaser’s applicable EN, DIN or manufacturer specification.	EN 10204 3.1 MTC, chemistry and dimensional inspection
Chinese Controlled-Expansion Alloy	GB/T 15018, 4J42	Common regional designation; confirm the current edition and required expansion range.	Chemistry, thermal expansion, dimensions and heat-treatment record
Thermal Expansion Testing	ASTM E228 or purchaser-approved dilatometry method	Test method selected according to specimen geometry and required temperature interval.	Expansion curve or mean coefficient over the specified temperature range
Tensile Testing	ASTM E8 / E8M or applicable regional method	Used when mechanical-property verification is required by the purchase specification.	Tensile strength, yield strength and elongation report
Custom Electronic Components	Customer drawing / OEM specification	Often the controlling requirement for lead frames, packages, feedthroughs and hermetic seals.	CTE, surface finish, cleanliness, flatness, grain size and dimensional inspection
Welding Products	Ni-Fe 42 matching filler or qualified project-specific consumable	Consumable selection depends on expansion matching, joint design and sealing process.	Consumable chemistry, lot traceability and procedure qualification

Available Product Forms

Invar 42 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	OD 1-300 mm, thin-wall capillary and drawing-based sizes available	Seamless or fabricated, annealed, cleaned and cut to length	Glass-to-metal seals, feedthrough sleeves, vacuum components and sensor housings	View Pipe & Tube
Round Bar	Diameter 1-300 mm, custom cut lengths available	Hot rolled, forged, annealed, peeled, ground or polished	Feedthrough pins, precision shafts, headers and machined sealing components	View Round Bar
Sheet & Plate	Thickness 0.2-80 mm, custom widths, lengths and cut blanks	Annealed, cold rolled, pickled, ground or precision flattened	Electronic packages, base plates, frames, covers and precision supports	View Sheet & Plate
Strip & Foil	Thickness 0.01-3 mm, precision slit widths and coil supply	Annealed, quarter-hard, half-hard or full-hard	Integrated-circuit lead frames, diaphragms, clips and stamped electronic parts	View Strip & Foil
Wire	Diameter 0.05-12 mm, coil, spool or straight-length supply	Annealed, cold drawn, bright cleaned or oxidation prepared	Lead-in wire, feedthrough pins, hermetic seals and electronic terminals	View Wire
Fasteners	Miniature and custom bolts, nuts, screws, studs and washers	Cold formed or machined, annealed or work hardened	Precision instruments, electronic assemblies and expansion-matched structures	View Fasteners
Fittings	Miniature sleeves, connectors, ferrules and drawing-based components	Machined or formed, annealed, cleaned and dimensionally inspected	Hermetic feedthroughs, vacuum systems, sensor packages and glass seals	View Fittings
Flanges	Miniature vacuum flanges, rings and custom drawing dimensions	Machined, annealed, ground and cleaned	Electronic packages, optical assemblies and precision vacuum connections	View Flanges
Forgings	Rings, discs, blocks and drawing-based precision blanks	Forged, annealed, rough machined or finish machined	Instrument frames, housings, support rings and precision expansion-matched parts	View Forgings
Welding Wire	Diameter 0.5-4.0 mm, spool, coil or straight-length supply	Matching Ni-Fe chemistry, clean bright finish and controlled diameter	Joining Alloy 42 assemblies where expansion compatibility must be maintained	View Welding Wire

Material Selection Guide

When to consider Invar 42

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	Why Invar 42 Helps	Common Product Form	Buyer Note
Glass-to-metal hermetic sealing	Its controlled expansion can match selected soft glasses during sealing and thermal cycling.	Wire, tube, strip, bar and machined feedthrough	Provide the exact glass grade, sealing temperature, component geometry and leak-rate requirement.
Semiconductor lead frames	Provides predictable expansion with good stampability in annealed or controlled cold-worked strip.	Precision strip and foil	Specify thickness tolerance, flatness, edge condition, temper and surface cleanliness.
Silicon-compatible electronic packaging	The expansion rate is closer to silicon than common structural steels or austenitic stainless steels.	Sheet, strip, plate, frame and machined housing	Confirm the complete temperature cycle and allowable package stress.
Vacuum and sensor feedthroughs	Controlled expansion helps reduce thermal mismatch across sealed joints.	Wire, pin, capillary tube, sleeve and fitting	Specify leak rate, electrical isolation, plating and surface preparation.
Precision dimensional components	Offers lower expansion than ordinary steels over its controlled operating range.	Bar, plate, ring and machined component	Provide the exact temperature interval because CTE changes significantly with temperature.
Bimetal and thermostat components	Can serve as a controlled low-expansion component in selected laminated thermal-response systems.	Sheet and strip	Specify active and passive layers, curvature requirement, thickness ratio and cycling conditions.

Why Choose Us

Supply and quality support for Invar 42

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.

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FAQ

Invar 42 questions from buyers

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

Invar 42 is mainly used for glass-to-metal seals, integrated-circuit lead frames, semiconductor packages, feedthrough pins, relay parts, vacuum components, lamp lead-in assemblies, electronic housings and other components requiring controlled thermal expansion.

Yes. Invar 42, Alloy 42 and NILO 42 are common commercial names associated with UNS K94100. Related designations include Werkstoff 1.3917, FeNi42 and the Chinese grade 4J42. Exact chemistry and expansion limits must still be checked against the purchase specification.

Invar 36 contains approximately 36% nickel and has a much lower expansion coefficient near room temperature. Alloy 42 contains approximately 41-42% nickel and has a higher, more uniform expansion rate selected to match certain glasses, ceramics and semiconductor materials. The two grades are not interchangeable in a precision seal or expansion-controlled assembly.

Alloy 42 is principally an iron-nickel alloy, while Kovar also contains approximately 17% cobalt. Kovar is generally selected to match hard borosilicate glass and certain ceramics, whereas Alloy 42 is commonly used with selected soft glasses, lead frames and silicon-related electronic packages. Material selection must be based on the complete expansion curve rather than room-temperature CTE alone.

ASTM F30 was historically the principal specification for Alloy 42 sealing products, but it was withdrawn in 2024 without replacement. ASTM B753 remains applicable to covered thermostat-component products. Many current purchases therefore use manufacturer specifications, customer drawings, Werkstoff 1.3917, FeNi42 or GB/T 15018 requirements.

Yes. Alloy 42 can be joined by suitable resistance, laser, electron-beam and inert-gas welding procedures. Welding can change local microstructure, stress and expansion behavior, so critical sealing assemblies should use a qualified procedure and may require a final anneal or dimensional-stability treatment.

Yes. Alloy 42 components are often nickel, copper, silver or gold plated depending on the electronic assembly and sealing process. Glass sealing requires carefully controlled surface cleanliness, oxide condition, heat treatment and thermal cycle. The glass composition and plating system should be included in the technical review.

Please provide UNS K94100 or the required regional designation, product form, dimensions, quantity, temper, chemistry limits, thermal-expansion range, surface finish, heat treatment, certificate requirements and destination. For sealing parts, also send the glass or ceramic grade, drawing, plating, cleanliness and leak-test requirements.

Invar 42