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UNS K94200 (FeNi42, 1.3917) Low Expansion Alloy

K94200 alloy is an iron alloy formulated for controlled thermal expansion. 1.3917 is the EN numeric designation for this material. FeNi42 is the EN chemical designation. And K94200 is the UNS number.

The properties of K94200 alloy include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare K94200 alloy to: low-expansion iron alloys (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

140 GPa 21 x 106 psi

Elongation at Break

5.0 to 32 %

Poisson's Ratio


Shear Modulus

54 GPa 7.8 x 106 psi

Shear Strength

330 to 410 MPa 48 to 60 x 103 psi

Tensile Strength: Ultimate (UTS)

500 to 710 MPa 73 to 100 x 103 psi

Tensile Strength: Yield (Proof)

270 to 650 MPa 39 to 94 x 103 psi

Thermal Properties

Curie Temperature

350 °C 660 °F

Melting Onset (Solidus)

1440 °C 2620 °F

Specific Heat Capacity

500 J/kg-K 0.12 BTU/lb-°F

Thermal Conductivity

15 W/m-K 8.7 BTU/h-ft-°F

Thermal Expansion

5.0 µm/m-K

Other Material Properties


8.2 g/cm3 510 lb/ft3

Electrical Conductivity: Equal Volume

2.7 % IACS

Electrical Conductivity: Equal Weight (Specific)

3.0 % IACS

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

35 to 130 MJ/m3

Resilience: Unit (Modulus of Resilience)

250 to 1460 kJ/m3

Stiffness to Weight: Axial

9.8 points

Stiffness to Weight: Bending

21 points

Strength to Weight: Axial

17 to 24 points

Strength to Weight: Bending

17 to 22 points

Thermal Diffusivity

3.7 mm2/s

Thermal Shock Resistance

49 to 70 points

Followup Questions

Further Reading

Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993

Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005