Invar® and Free-Cut Invar “36”® Alloy FM Properties

Invar properties physical mechanical expansion chemistry specificationsEFINEA is the unsurpassed leader in supplying nickel-iron alloys to the industry. You will find Invar® and Free-Cut Invar “36”® Alloy FM (Free Machining grade) individual property tables for evaluating these two alloys. As a reference we have provided the comprehensive thermal expansion data, physical and mechanical properties, chemistry, and applicable specifications for Invar and Free-Cut Invar “36”.

 

To download an Invar® alloy data sheet, a Free-Cut Invar “36”® Alloy FM data sheet, or any other Controlled Expansion Alloy data sheets, please go to the Data Sheets section in our Technical Library.

Invar Average Coefficient of Thermal Expansion µm/m • °C

Temperature Range °CUNS NO. K93603,
871°C 1 hour, Furnace Cool
Temperature Range °CUNS NO. K93603,
871°C 1 hour, Furnace Cool
30 to 100 1.9330 to 300 6.05
30 to 1502.3830 to 3507.51
30 to 1501.2 to 2.7*30 to 400 8.69
30 to 2003.0330 to 500 10.47
30 to 2504.3630 to 600 11.75
Source: *ASTM F1684-06 (2021) Table 5; Average linear coefficient range limits; ASTM F1684-06 (2021) Table X2.1

To compare the average linear coefficient of thermal expansion across our line of controlled expansion glass and sealing alloys, please refer to the Thermal Expansion Table.

Invar Typical Physical Properties

Densitylb/cu in0.291
Specific Gravity8.05
Curie Temp°F535
°C279.4
Melting Range°F2600
°C1427
Electrical Resistivity (70°F)ohm-cir mil/ft495
microhm-cm82.92
Thermal ConductivityBTU-in/sq. ft-hr-°F72.85
W/m °C10
Mean Specific HeatBTU/lb/°F0.123
Source: CarTech Invar 36 Alloy Data Sheet v.3/15/04

Invar Typical Mechanical Properties

Tensile Strengthksi58 min. - 72.5 max.
MPa400 min. - 500 max.
Yield Strengthksi33.33 min. - 50.7 max.
MPa230 min. - 350 max.
Elongation% in 2"34
HardnessRockwell HRBB60 min. - 85 max.
Modulus of Elasticity
• Annealed Bar & Stripksi20.5 x 103
• Cold Rolledksi21.5 x 103
Source: ASTM F1684-06 (2021) Table 4 Plate

Invar Chemistry

Iron nominalBalanceA
Nickel nominal36A
Cobalt max.0.50
Manganese max.0.60
Carbon max0.05
Silicon max.0.40
Phosphorus max.0.015
Sulfur max.0.015
Chromium max.0.25
Aluminum max.0.10B
Magnesium max.0.10B
Zirconium max.0.10B
Titanium max.0.10B
Source: ASTM F1684-06 (2021) UNS K93603 Table 1
A The iron and nickel requirements are nominal. B The total of aluminum, magnesium, titanium, and zirconium shall not exceed 0.20%

Invar Specifications

Standard Grade
ASTM F1684AMS 1-23011 CL 7MIL-1-23011 CL 7UNS K93603 (Plate, Sheet)

Free-Cut Invar “36”® Alloy FM

Free-Cut Invar "36"® Alloy FM Mean Coefficient of Thermal Expansion

Temperature
77°F to
Coefficient
x 10-6/°F
Temperature
25°C to
Coefficient
x 10-6/°C
2120.911001.64
3021.321502.38
3921.692003.04
4822.342504.21
5723.263005.87
Source: CarTech Free-Cut Invar "36" Alloy Data Sheet v.3/15/04

Free-Cut Invar "36"® Alloy FM Free-Cut Typical Physical Properties

Densitylb/cu in0.291
Specific Gravity8.05
Curie Temp°F535
°C280
Melting Point°F2600
Electrical Resistivity (70°F)ohm-cir mil/ft495.0
Thermal ConductivityBTU-in/sq. ft-hr-°F72.6
W/m °C10
Mean Specific HeatBTU/lb-°F0.1230
Source: CarTech Free-Cut Invar “36” Alloy Data Sheet v.3/15/04

Free-Cut Invar "36"® Alloy FM Typical Mechanical Properties

Annealed BarsCold Drawn Bars
Tensile Strengthksi6590
MPa448621
Yield Strengthksi4070
MPa276483
Reduction in Area%6560
Elongation% in 2"3520
HardnessRockwell B7090
Modulus of Elasticityksi20.521.5
Source: CarTech Free-Cut Invar "36" Alloy Data Sheet v.3/15/04

Free-Cut Invar "36"® Alloy FM Free-Cut Chemistry

nominal % unless noted
IronBal
Nickel36.00
Manganese0.90
Silicon0.35
Cobalt0.20
Selenium0.20
Source: CarTech Free-Cut Invar “36” Alloy Data Sheet v.3/15/04

Free-Cut Invar "36"® Alloy FM Specifications

Free Machining Grade Round Bar, Rod
ASTM F1684UNS K93050

For additional information on specifications of the materials distributed by EFINEA, please visit the websites of the international organizations that develop and publish technical standards: ASTM International and ASM International.