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AWS ER80S-Ni3 or ER55S-Ni3 (K31240) Weld Metal

AWS ER80S-Ni3 is a weld metal formulated for joining alloy steels. Cited properties are appropriate for the post-weld heat treated (PWHT) condition. ER80S-Ni3 is the AWS designation for this material. K31240 is the UNS number.

It has a moderately high ductility among alloy steel welding fillers. In addition, it has a fairly high thermal conductivity and a moderately low electrical conductivity.

The graph bars on the material properties cards below compare AWS ER80S-Ni3 to: alloy steel welding fillers (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

190 GPa 27 x 106 psi

Elongation at Break

27 %

Poisson's Ratio


Shear Modulus

72 GPa 10 x 106 psi

Tensile Strength: Ultimate (UTS)

630 MPa 91 x 103 psi

Tensile Strength: Yield (Proof)

530 MPa 76 x 103 psi

Thermal Properties

Latent Heat of Fusion

260 J/g

Melting Completion (Liquidus)

1450 °C 2640 °F

Melting Onset (Solidus)

1410 °C 2570 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

51 W/m-K 29 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.4 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

4.0 % relative


7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.7 kg CO2/kg material

Embodied Energy

23 MJ/kg 9.8 x 103 BTU/lb

Embodied Water

52 L/kg 6.3 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

160 MJ/m3

Resilience: Unit (Modulus of Resilience)

740 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

22 points

Strength to Weight: Bending

21 points

Thermal Diffusivity

14 mm2/s

Thermal Shock Resistance

19 points

Alloy Composition

Iron (Fe) 93.2 to 96.6
Nickel (Ni) 3.0 to 3.8
Manganese (Mn) 0 to 1.3
Silicon (Si) 0.4 to 0.8
Copper (Cu) 0 to 0.35
Carbon (C) 0 to 0.12
Phosphorus (P) 0 to 0.025
Sulfur (S) 0 to 0.025
Residuals 0 to 0.5

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

AWS A5.28: Specification for Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding

Welding Metallurgy, 2nd ed., Sindo Kou, 2003