Steel ER120S-1 PWHT
Heat-treated state
UNS K21030
PWHT = post-weld heat treated
Use when code or distortion control requires stress relief; expect a strength drop of roughly 50–100 MPa with slightly higher ductility.
Values for the PWHT condition
Other ER120S-1 tempers and conditions
ER120S-1 is listed in 3 conditions; see the grade overview at ER120S-1.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PWHTThis page Post-weld heat treated | Use when code or distortion control requires stress relief; expect a strength drop of roughly 50–100 MPa with slightly higher ductility. | 740 | 810 | 20 | 23 HRC | 7 % IACS |
AWDefault As-welded deposit | Standard qualification and production condition for 120 ksi joints on HY-100/HSLA-100 and armor plate. | 810 | 880 | 18 | 27 HRC | — |
As-welded, GTAW with 100% argon | Pick for root passes, thin sections and repair where the lowest oxygen/highest-toughness deposit is wanted. | 830 | 900 | 19 | 28 HRC | 7 % IACS |
What is ER120S-1 PWHT?
ER120S-1 PWHT is ER120S-1 heat treated to PWHT — use when code or distortion control requires stress relief; expect a strength drop of roughly 50–100 MPa with slightly higher ductility. ER120S-1 PWHT has a yield strength of 740 MPa (107 ksi) and a tensile strength of 810 MPa (117 ksi) — stronger than 83% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). ER120S-1 PWHT has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F). AW is the default condition FabDigit quotes; PWHT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- High strength — 740 MPa (107 ksi), better than 83% of steel grades
ER120S-1 PWHT properties
Typical room-temperature values for ER120S-1 PWHT; 23 are specific to this condition. Other listed values are ER120S-1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
ER120S-1 PWHT has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
ER120S-1 PWHT has a yield strength of 740 MPa (107 ksi) and a tensile strength of 810 MPa (117 ksi) — stronger than 83% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
ER120S-1 PWHT is rated for continuous service to 450°C (842 °F). It conducts heat at 39 W/m·K (22.5 BTU/hr·ft·°F), worse than 67% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
ER120S-1 PWHT conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of ER120S-1 PWHT takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability6
ER120S-1 PWHT's machinability is fair (42/100, worse than 73% of steel grades); weldability good (65/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ER120S-1 PWHT
Is ER120S-1 easy to machine?
Weld deposit at ~270 HB machines like Q&T 4340 at low hardness — use carbide, rigid setups and modest speeds; grind rather than mill for cap dressing.
Can ER120S-1 be welded?
Low-hydrogen practice is mandatory: dry gas, clean plate, preheat/interpass per base-metal carbon equivalent (typically 100–150 °C for HY-100), controlled heat input to keep both strength and −51 °C toughness.
Can ER120S-1 be formed, bent or molded?
Not a forming grade; the product is drawn wire supplied on spools or as cut TIG lengths — protect from moisture and mechanical damage to preserve feedability.
What surface finishes work on ER120S-1?
Weld metal rusts quickly; blast or grind, then prime/paint or metallize. Avoid electroplating without baking due to hydrogen embrittlement risk at this strength level.
ER120S-1 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CAWS A5.28 max | ≤ 0.1 | 0.08 |
| Mn | 1.4 – 1.8 | 1.6 |
| Si | 0.25 – 0.6 | 0.45 |
| Ni | 1.9 – 2.6 | 2.25 |
| Cr | 0.3 – 0.65 | 0.45 |
| Mo | 0.4 – 0.65 | 0.55 |
| V | ≤ 0.03 | — |
| Tideoxidizer/microalloy | ≤ 0.1 | 0.03 |
| Zr | ≤ 0.1 | 0.03 |
| Al | ≤ 0.1 | 0.03 |
| Cuincluding copper coating | ≤ 0.25 | — |
| P | ≤ 0.01 | — |
| S | ≤ 0.01 | — |
| Fe | balance | — |
ER120S-1 PWHT — frequently asked
What is ER120S-1 PWHT used for?
ER120S-1 PWHT is typically used for high-strength structural steel welding, military/armor plate repair, high-pressure vessel welds and off-highway equipment. In short: 120 ksi class weld metal; matches HY-100 and armor; toughness rated to −51 °C.
What is the yield strength of ER120S-1 PWHT?
ER120S-1 PWHT has a typical yield strength of 740 MPa (107 ksi) and a tensile strength of 810 MPa (117 ksi) — stronger than 83% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is ER120S-1 PWHT easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Weld deposit at ~270 HB machines like Q&T 4340 at low hardness — use carbide, rigid setups and modest speeds; grind rather than mill for cap dressing.
Can ER120S-1 PWHT be welded?
Yes — weldability is rated good (65/100). Low-hydrogen practice is mandatory: dry gas, clean plate, preheat/interpass per base-metal carbon equivalent (typically 100–150 °C for HY-100), controlled heat input to keep both strength and −51 °C toughness.
What surface finishes work on ER120S-1 PWHT?
Weld metal rusts quickly; blast or grind, then prime/paint or metallize. Avoid electroplating without baking due to hydrogen embrittlement risk at this strength level.
Can ER120S-1 PWHT be formed, bent or molded?
Not a forming grade; the product is drawn wire supplied on spools or as cut TIG lengths — protect from moisture and mechanical damage to preserve feedability.
What is the maximum service temperature of ER120S-1 PWHT?
ER120S-1 PWHT is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER120S-1-AW and ER120S-1 PWHT?
AW is the default condition — standard qualification and production condition for 120 ksi joints on HY-100/HSLA-100 and armor plate. PWHT: use when code or distortion control requires stress relief; expect a strength drop of roughly 50–100 MPa with slightly higher ductility. Yield strength is 810 MPa in AW versus 740 MPa in PWHT.
Sources
- AWS A5.28/A5.28M — Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding — American Welding Society (2020)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- High-strength low-alloy GMAW/GTAW wire datasheets (120 ksi class) — Lincoln Electric / ESAB / voestalpine Böhler Welding (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.