Stainless Steel ER309Cb PWHT
Heat-treated state
PWHT = post-weld heat treated
Use when the Cr-Mo or C-steel base metal mandates PWHT; Nb stabilization keeps the overlay resistant to sensitization, but some ferrite may transform toward sigma.
Values for the PWHT condition
Other ER309Cb tempers and conditions
ER309Cb is listed in 3 conditions; see the grade overview at ER309Cb.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-welded submerged-arc / strip-cladding overlay deposit | Pick for high-deposition SAW wire or strip cladding of pressure-vessel steel; higher heat input gives slightly lower strength and toughness scatter. | 385 | 570 | 33 | 185 HB | 2.2 % IACS |
PWHTThis page Post-weld heat treated | Use when the Cr-Mo or C-steel base metal mandates PWHT; Nb stabilization keeps the overlay resistant to sensitization, but some ferrite may transform toward sigma. | 400 | 580 | 30 | 195 HB | 2.2 % IACS |
AWDefault As-welded deposit | Standard condition for classification testing and most overlay/dissimilar-joint service — use unless PWHT is imposed by the base metal. | 410 | 600 | 35 | 190 HB | 2.2 % IACS |
What is ER309Cb PWHT?
ER309Cb PWHT is ER309Cb heat treated to PWHT — use when the Cr-Mo or C-steel base metal mandates PWHT; Nb stabilization keeps the overlay resistant to sensitization, but some ferrite may transform toward sigma. ER309Cb PWHT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 196 GPa (28.4 Msi). ER309Cb 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 — 88/100, better than 91% of stainless steel grades
Limitations
- Hard to polish — 60/100, worse than 80% of stainless steel grades
ER309Cb PWHT properties
Typical room-temperature values for ER309Cb PWHT; 22 are specific to this condition. Other listed values are ER309Cb reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
ER309Cb 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
ER309Cb PWHT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
ER309Cb PWHT is rated for continuous service to 800°C (1,472 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), better than 53% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
ER309Cb PWHT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental2
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of ER309Cb PWHT takes about 55 MJ of energy and emits 4.8 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
ER309Cb PWHT's machinability is poor (31/100, worse than 65% of stainless 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 ER309Cb PWHT
Is ER309Cb easy to machine?
Overlay machines like Type 309/347: low speed, heavy positive-rake carbide, rigid setup and flood coolant to fight work hardening and gumming.
Can ER309Cb be welded?
Run GTAW/GMAW/SAW with Ar or Ar+2%CO2 (or 100% Ar + He for TIG), interpass ≤150 °C and limited heat input to hold ferrite and avoid hot cracking; ideal buffer layer under 347/321 or before nickel-alloy cover passes.
Can ER309Cb be formed, bent or molded?
Supplied as cold-drawn wire; bend TIG rods only gently — the deposit itself work-hardens rapidly and is normally not cold formed.
What surface finishes work on ER309Cb?
Grind, pickle and passivate the overlay to restore the passive film; avoid carbon-steel tooling contamination, no anodizing applies.
ER309Cb 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 |
|---|---|---|
| C≤0.03 for the low-carbon ER309LNb variant | ≤ 0.12 | 0.06 |
| Cr | 23 – 25 | 24 |
| Ni | 12 – 14 | 13 |
| NbNb+Ta reported as Cb; stabilizing addition | 0.7 – 1 | 0.85 |
| Mn | 1 – 2.5 | 1.8 |
| SiSi-enhanced ER309LNbSi types run 0.65–1.00 | 0.3 – 0.65 | 0.45 |
| Moresidual | ≤ 0.75 | — |
| Curesidual | ≤ 0.75 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
ER309Cb PWHT — frequently asked
What is ER309Cb PWHT used for?
ER309Cb PWHT is typically used for stabilized cladding and weld overlays, buffer layers under 347 or 321 weld metal, dissimilar-metal joints requiring Nb stabilization, transition welds ahead of nickel-alloy cover passes, submerged-arc overlay of pressure vessel shells and repair of stabilized stainless-clad equipment. In short: stabilized 309 overlay wire; buffer layer for 347/321; resists intergranular attack.
What is the yield strength of ER309Cb PWHT?
ER309Cb PWHT has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 580 MPa (84.1 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is ER309Cb PWHT easy to machine?
Not especially — machinability is rated poor (31/100, worse than 65% of stainless steel grades). Overlay machines like Type 309/347: low speed, heavy positive-rake carbide, rigid setup and flood coolant to fight work hardening and gumming.
Can ER309Cb PWHT be welded?
Yes — weldability is rated excellent (88/100). Run GTAW/GMAW/SAW with Ar or Ar+2%CO2 (or 100% Ar + He for TIG), interpass ≤150 °C and limited heat input to hold ferrite and avoid hot cracking; ideal buffer layer under 347/321 or before nickel-alloy cover passes.
What surface finishes work on ER309Cb PWHT?
Grind, pickle and passivate the overlay to restore the passive film; avoid carbon-steel tooling contamination, no anodizing applies.
Can ER309Cb PWHT be formed, bent or molded?
Supplied as cold-drawn wire; bend TIG rods only gently — the deposit itself work-hardens rapidly and is normally not cold formed.
What is the maximum service temperature of ER309Cb PWHT?
ER309Cb PWHT is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER309Cb-AW and ER309Cb AW-SAW?
AW is the default condition — standard condition for classification testing and most overlay/dissimilar-joint service — use unless PWHT is imposed by the base metal. AW-SAW: pick for high-deposition SAW wire or strip cladding of pressure-vessel steel; higher heat input gives slightly lower strength and toughness scatter. Yield strength is 410 MPa in AW versus 385 MPa in AW-SAW.
Sources
- AWS A5.9/A5.9M — Bare Stainless Steel Welding Electrodes and Rods — American Welding Society (2017)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Stainless filler metal datasheets (309/309LNb class) — Böhler Welding / Sandvik / ESAB (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.