Stainless Steel ER309 PWHT
Heat-treated state
UNS S30980 · EN 23 12
PWHT = post-weld heat treated
Use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover.
Values for the PWHT condition
Other ER309 tempers and conditions
ER309 is listed in 5 conditions; see the grade overview at ER309.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PWHTThis page Post-weld heat treated | Use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover. | 300 | 550 | 45 | 160 HB | 2.2 % IACS |
AW | High-deposition strip/wire cladding and heavy-section joints; properties depend strongly on flux, dilution runs higher. | 380 | 580 | 35 | 180 HB | 2.2 % IACS |
AW | Cut-length TIG rod deposit; cleanest, lowest-oxygen weld metal with the best toughness — pick for root passes and thin sections. | 390 | 590 | 40 | 175 HB | 2.2 % IACS |
AWDefault As-welded deposit | Standard reference condition: undiluted all-weld-metal tested as deposited, no post-weld heat treatment. | 400 | 600 | 38 | 180 HB | 2.2 % IACS |
AW | Spooled solid wire deposit for semi-automatic/robotic overlay; slightly higher strength and lower toughness than TIG because of oxidising shielding gas. | 410 | 610 | 36 | 185 HB | 2.2 % IACS |
What is ER309 PWHT?
ER309 PWHT is ER309 heat treated to PWHT — use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover. ER309 PWHT has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 196 GPa (28.4 Msi). ER309 PWHT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F). AW is the default condition FabDigit quotes; PWHT is available on request or by drawing note.
Advantages
- Readily welded — 92/100, better than 98% of stainless steel grades
- High service temperature — 1,000°C (1,832 °F), better than 88% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Good corrosion resistance — 76/100, better than 80% of stainless steel grades
- Forms and bends easily — 70/100, better than 79% of stainless steel grades
ER309 PWHT properties
Typical room-temperature values for ER309 PWHT; 23 are specific to this condition. Other listed values are ER309 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
ER309 PWHT has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
ER309 PWHT has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
ER309 PWHT is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
ER309 PWHT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (76/100), better than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of ER309 PWHT takes about 62 MJ of energy and emits 5.2 kg of CO₂ — more than 75% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
ER309 PWHT's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (92/100); formability very good (70/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ER309 PWHT
Is ER309 easy to machine?
Machining applies to the deposit/overlay: austenitic, gummy and work-hardening — rigid setup, sharp positive-rake carbide, heavy feed, flood coolant, no dwelling.
Can ER309 be welded?
Run with DCEN (GTAW) or DCEP (GMAW), Ar or Ar+2%O₂/Ar-He, low heat input and interpass ≤150 °C; aim for 8–15 FN ferrite to avoid hot cracking in dilute dissimilar joints.
Can ER309 be formed, bent or molded?
Supplied as cold-drawn wire; keep spool cast/helix within spec and use U-groove or knurl-free drive rolls plus a low-friction liner to prevent birdnesting.
What surface finishes work on ER309?
Pickle and passivate or mechanically blend the bead; do not anodise — grinding debris from carbon steel must be removed to avoid rust staining on the overlay.
ER309 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 |
|---|---|---|
| Cnon-L grade; ER309L is ≤0.03 | ≤ 0.12 | 0.08 |
| Cr | 23 – 25 | 24 |
| Ni | 12 – 14 | 13 |
| Mn | 1 – 2.5 | 1.8 |
| SiER309Si raises Si to 0.65–1.00 | 0.3 – 0.65 | 0.45 |
| Moresidual | ≤ 0.75 | — |
| Curesidual | ≤ 0.75 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
ER309 PWHT — frequently asked
What is ER309 PWHT used for?
ER309 PWHT is typically used for dissimilar joints between carbon steel and stainless steel, buffer layers under stainless or nickel-alloy overlay, weld overlay cladding of carbon steel vessels, stainless-clad plate seam and edge welds, transition joints in piping systems and repair welds on 309-type heat-resisting fabrications. In short: standard dissimilar-metal filler; tolerates high carbon-steel dilution; service to 1000 °C.
What is the yield strength of ER309 PWHT?
ER309 PWHT has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is ER309 PWHT easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machining applies to the deposit/overlay: austenitic, gummy and work-hardening — rigid setup, sharp positive-rake carbide, heavy feed, flood coolant, no dwelling.
Can ER309 PWHT be welded?
Yes — weldability is rated excellent (92/100). Run with DCEN (GTAW) or DCEP (GMAW), Ar or Ar+2%O₂/Ar-He, low heat input and interpass ≤150 °C; aim for 8–15 FN ferrite to avoid hot cracking in dilute dissimilar joints.
What surface finishes work on ER309 PWHT?
Pickle and passivate or mechanically blend the bead; do not anodise — grinding debris from carbon steel must be removed to avoid rust staining on the overlay.
Can ER309 PWHT be formed, bent or molded?
Supplied as cold-drawn wire; keep spool cast/helix within spec and use U-groove or knurl-free drive rolls plus a low-friction liner to prevent birdnesting.
What is the maximum service temperature of ER309 PWHT?
ER309 PWHT is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER309-AW and ER309 PWHT?
AW is the default condition — standard reference condition: undiluted all-weld-metal tested as deposited, no post-weld heat treatment. PWHT: use when the fabrication is solution annealed after welding: ferrite is partly dissolved, strength drops and ductility/corrosion resistance recover. Yield strength is 400 MPa in AW versus 300 MPa in PWHT.
Sources
- AWS A5.9/A5.9M — Bare Stainless Steel Welding Electrodes and Rods — AWS (2017)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Specialty Handbook — Stainless Steels — ASM International (1994)
- ER309 / 309Si solid wire datasheets — Böhler Welding / ESAB / Lincoln Electric (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.