Steel ER70S-A1 PWHT620
Heat-treated state
UNS K11235
Standard condition for C-Mo pressure piping and boilers; softens the deposit, restores ductility and stabilises creep performance.
Values for the PWHT620 condition
Other ER70S-A1 tempers and conditions
ER70S-A1 is listed in 2 conditions; see the grade overview at ER70S-A1.
- PWHT620
- AW
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PWHT620This page PWHT | Standard condition for C-Mo pressure piping and boilers; softens the deposit, restores ductility and stabilises creep performance. | 460 | 550 | 28 | 165 HB | — |
AWDefault As-welded deposit | Use for as-deposited joints where PWHT is not mandated; highest strength and hardness, lowest ductility. | 500 | 590 | 25 | 12 HRC | 8.5 % IACS |
What is ER70S-A1 PWHT620?
ER70S-A1 PWHT620 is ER70S-A1 heat treated to PWHT620 — standard condition for C-Mo pressure piping and boilers; softens the deposit, restores ductility and stabilises creep performance. ER70S-A1 PWHT620 has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 55% of steel grades. Elongation at break is 28% and the elastic modulus is 205 GPa (29.7 Msi). ER70S-A1 PWHT620 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). AW is the default condition FabDigit quotes; PWHT620 is available on request or by drawing note.
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- Ductile — tolerates forming and impact — 28%, better than 89% of steel grades
- Readily welded — 88/100, better than 87% of steel grades
ER70S-A1 PWHT620 properties
Typical room-temperature values for ER70S-A1 PWHT620; 10 are specific to this condition. Other listed values are ER70S-A1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
ER70S-A1 PWHT620 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical17
ER70S-A1 PWHT620 has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 55% of steel grades. Elongation at break is 28% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
ER70S-A1 PWHT620 is rated for continuous service to 500°C (932 °F). It conducts heat at 41 W/m·K (23.7 BTU/hr·ft·°F), worse than 62% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
ER70S-A1 PWHT620 conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of ER70S-A1 PWHT620 takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability7
ER70S-A1 PWHT620's machinability is fair (52/100, better than 52% of steel grades); weldability excellent (88/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ER70S-A1 PWHT620
Is ER70S-A1 easy to machine?
Weld caps machine like a normalized C-Mo steel (~60 % of AISI 1212); PWHT first to avoid hard as-welded zones.
Can ER70S-A1 be welded?
GMAW with Ar+(5–25 %)CO₂ or GTAW with Ar; preheat 100–200 °C on heavy C-Mo sections and PWHT at 605–635 °C per code.
Can ER70S-A1 be formed, bent or molded?
Supplied as drawn copper-coated wire or cut TIG rod; keep feed rolls and liners clean to avoid arc instability.
What surface finishes work on ER70S-A1?
Deposit rusts like plain steel — grind, wire-brush and paint or insulate; no anodizing, plating only for special service.
ER70S-A1 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 | ≤ 0.12 | 0.09 |
| Mn | ≤ 1.3 | 1.1 |
| Si | 0.4 – 0.7 | 0.55 |
| Mocreep-strengthening addition | 0.4 – 0.65 | 0.5 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.04 | 0.01 |
| Cuincludes any copper coating | ≤ 0.35 | 0.2 |
| Fe | balance | — |
ER70S-A1 PWHT620 — frequently asked
What is ER70S-A1 PWHT620 used for?
ER70S-A1 PWHT620 is typically used for carbon-moly steel pipe welding, power plant piping, refinery process piping and elevated temperature service welds. In short: creep-resistant C-Mo deposit; entry-level alloy pipe filler; service to 450 °C.
What is the yield strength of ER70S-A1 PWHT620?
ER70S-A1 PWHT620 has a typical yield strength of 460 MPa (66.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 55% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is ER70S-A1 PWHT620 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Weld caps machine like a normalized C-Mo steel (~60 % of AISI 1212); PWHT first to avoid hard as-welded zones.
Can ER70S-A1 PWHT620 be welded?
Yes — weldability is rated excellent (88/100). GMAW with Ar+(5–25 %)CO₂ or GTAW with Ar; preheat 100–200 °C on heavy C-Mo sections and PWHT at 605–635 °C per code.
What surface finishes work on ER70S-A1 PWHT620?
Deposit rusts like plain steel — grind, wire-brush and paint or insulate; no anodizing, plating only for special service.
Can ER70S-A1 PWHT620 be formed, bent or molded?
Supplied as drawn copper-coated wire or cut TIG rod; keep feed rolls and liners clean to avoid arc instability.
What is the maximum service temperature of ER70S-A1 PWHT620?
ER70S-A1 PWHT620 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER70S-A1-AW and ER70S-A1 PWHT620?
AW is the default condition — use for as-deposited joints where PWHT is not mandated; highest strength and hardness, lowest ductility. PWHT620: standard condition for C-Mo pressure piping and boilers; softens the deposit, restores ductility and stabilises creep performance. Yield strength is 500 MPa in AW versus 460 MPa in PWHT620.
Sources
- AWS A5.28/A5.28M — Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding — American Welding Society (2020)
- ASME BPVC Section II Part C / Part D — ASME (2023)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- C-Mo solid wire product data (ER70S-A1 class) — Lincoln Electric / ESAB / Böhler (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.