Invar 36 4J36 UNS K93600 Low Expansion Precision Alloy

Short Description:

Invar 36 Alloy Overview Invar 36 / 4J36 is an iron-nickel precision alloy containing approximately 36% nickel. Its defining characteristic is a very low coefficient of thermal expansion over a controlled temperature range, making it suitable for components where dimensional stability is more important than conventional structural strength. Thermal expansion performance is affected by chemical composition, melting practice, heat treatment, cold work and the temperature…

Grade:: Invar 36 4J36 UNS K93600 Low Expansion Precision Alloy
Standard:: Applicable ASTM standard (by alloy grade and product form)
Surface:: Mill finish, pickled, polished, or as required
Diameter:: Not applicable

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Invar 36 Alloy Overview

Invar 36 / 4J36 is an iron-nickel precision alloy containing approximately 36% nickel. Its defining characteristic is a very low coefficient of thermal expansion over a controlled temperature range, making it suitable for components where dimensional stability is more important than conventional structural strength.

Thermal expansion performance is affected by chemical composition, melting practice, heat treatment, cold work and the temperature range used for measurement. The required coefficient of thermal expansion and test range should therefore be stated on the drawing or purchase specification.

Invar 36 Product Specification

Item	Supply Reference
Grade	Invar 36 / 4J36 / FeNi36
UNS designation	K93600
W.Nr.	1.3912
Common reference standards	ASTM F1684 and ASTM A658 may be referenced depending on product form and project requirements; confirm the required edition with the inquiry
Alloy family	Low-expansion nickel-iron precision alloy
Key purchasing requirement	Product form, dimensions, condition, CTE test range, tolerances and certification

Supply Forms and Custom Processing

Product Form	Production Review Information
Sheet, plate and cold-rolled strip	Thickness, width, length or coil weight, flatness, surface and edge condition
Round bar, rod and forged bar	Diameter, tolerance, straightness, cut length and machining allowance
Wire and flat wire	Diameter or thickness × width, coil / spool condition, temper and surface
Cut or machined components	Drawing, dimensional tolerances, datum requirements, machining allowance and inspection plan

Invar 36 Technical Data

Chemical composition reference — final acceptance must follow the ordered specification and material certificate.

Grade	Range	Ni	Fe	C	Mn	Si	P	S
Invar 36	Min	35	Balance	—	0.2	—	—	—
Invar 36	Max	37	Balance	0.05	0.6	0.3	0.02	0.02

Mechanical properties reference at 20°C — values can vary with product form, dimensions and condition.

Tensile Strength	0.2% Yield Strength	Elongation
490 MPa	240 MPa	42%

Design Factor	Engineering Note
Thermal expansion	Very low over the controlled service range; specify the required CTE range and test method
Cryogenic service	Used in selected liquefied-gas and cryogenic systems after design, toughness and joining review
Machining	Use rigid tooling, controlled feeds and allowances appropriate for a tough nickel-iron alloy
Joining	Welding and brazing procedures must preserve dimensional and service requirements

Discuss Invar 36 Dimensions and CTE Requirements

Invar 36 Applications

Application Area	Typical Use
Precision measurement	Standards of length, measuring devices, gauges and positioning structures
Optical and laser systems	Supports, mounts and structures requiring dimensional stability
Aerospace and composites	Composite tooling, moulds and precision fixtures
Cryogenic equipment	Selected tanks, piping components and transport systems for liquefied gases
Electronics and temperature control	Electronic components, thermostat rods, relays and bimetallic assemblies

Quality Inspection and Documentation

Inspection Item	Available Review
Material identity	Chemical composition, grade and heat / batch traceability
Dimensions	Thickness or diameter, width, length, straightness, flatness and tolerances
Mechanical properties	Tensile testing according to the ordered product specification when required
Thermal expansion	CTE testing range, orientation, specimen and acceptance criteria must be agreed before production
Documents	Inspection certificate, test report, marking and additional project documentation as specified

Packaging and Export Delivery

Sheet and plate	Surface protection, moisture barrier and reinforced wooden cases or pallets according to size
Bar and rod	Bundled or boxed with end protection and heat / batch identification
Strip and wire	Coils or spools with interleaving and moisture-resistant outer packing where required
Identification	Grade, dimensions, heat / batch number, net weight and purchase-order reference

RFQ Confirmation Checklist

Please Provide	Required Detail
Grade and standard	Invar 36 / 4J36, specification and required edition
Product form and dimensions	Thickness or diameter, width, length, tolerances and quantity
Thermal requirement	CTE limit, temperature range and test method
Processing	Cutting, machining allowance, heat treatment, surface and edge requirements
Quality and delivery	Certificate, inspection, marking, packing and destination