AWS ER120S-1 or ER83S-1 (K21030) Weld Metal
AWS ER120S-1 is a weld metal formulated for joining alloy steels. Cited properties are appropriate for the as-welded condition. ER120S-1 is the AWS designation for this material. K21030 is the UNS number.
It has a fairly low ductility among alloy steel welding fillers. In addition, it has a very high tensile strength and a moderately high embodied energy.
The graph bars on the material properties cards below compare AWS ER120S-1 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
17 %
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
930 MPa 130 x 103 psi
Tensile Strength: Yield (Proof)
830 MPa 120 x 103 psi
Thermal Properties
Latent Heat of Fusion
260 J/g
Melting Completion (Liquidus)
1460 °C 2650 °F
Melting Onset (Solidus)
1410 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
46 W/m-K 27 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.8 % IACS
Electrical Conductivity: Equal Weight (Specific)
9.0 % IACS
Otherwise Unclassified Properties
Base Metal Price
4.2 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.9 kg CO2/kg material
Embodied Energy
25 MJ/kg 11 x 103 BTU/lb
Embodied Water
56 L/kg 6.7 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
150 MJ/m3
Resilience: Unit (Modulus of Resilience)
1850 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
33 points
Strength to Weight: Bending
27 points
Thermal Diffusivity
13 mm2/s
Thermal Shock Resistance
27 points
Alloy Composition
| Fe | 92.4 to 96.1 | |
| Ni | 2.0 to 2.8 | |
| Mn | 1.4 to 1.8 | |
| Mo | 0.3 to 0.65 | |
| Si | 0.25 to 0.6 | |
| Cr | 0 to 0.6 | |
| Cu | 0 to 0.25 | |
| C | 0 to 0.1 | |
| Al | 0 to 0.1 | |
| Ti | 0 to 0.1 | |
| Zr | 0 to 0.1 | |
| V | 0 to 0.030 | |
| P | 0 to 0.010 | |
| S | 0 to 0.010 | |
| res. | 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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015