Stainless Steel E309Nb PWHT
Heat-treated state
UNS W30917
PWHT = post-weld heat treated
Condition after the joint is stress-relieved with the ferritic base metal; Nb stabilization keeps the deposit sensitization-free but ferrite may partly transform, lowering toughness.
Values for the PWHT condition
Other E309Nb tempers and conditions
E309Nb is listed in 2 conditions; see the grade overview at E309Nb.
- PWHT
- AW
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PWHTThis page Post-weld heat treated | Condition after the joint is stress-relieved with the ferritic base metal; Nb stabilization keeps the deposit sensitization-free but ferrite may partly transform, lowering toughness. | 400 | 590 | 32 | 11 HRC | 2.3 % IACS |
AWDefault As-welded deposit | Default condition for dissimilar-metal joints and buffer layers; use as-deposited unless the base metal demands PWHT. | 420 | 600 | 35 | 12 HRC | 2.2 % IACS |
What is E309Nb PWHT?
E309Nb PWHT is E309Nb heat treated to PWHT — condition after the joint is stress-relieved with the ferritic base metal; Nb stabilization keeps the deposit sensitization-free but ferrite may partly transform, lowering toughness. E309Nb PWHT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 196 GPa (28.4 Msi). E309Nb 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 — 85/100, better than 87% of stainless steel grades
Limitations
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
- Low fracture toughness — 90 MPa·√m (81.9 ksi·√in), worse than 75% of stainless steel grades
E309Nb PWHT properties
Typical room-temperature values for E309Nb PWHT; 23 are specific to this condition. Other listed values are E309Nb reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
E309Nb 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).
Mechanical17
E309Nb PWHT has a yield strength of 400 MPa (58 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
E309Nb PWHT is rated for continuous service to 425°C (797 °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
E309Nb PWHT conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of E309Nb PWHT takes about 70 MJ of energy and emits 5.5 kg of CO₂ — more than 81% of stainless steel grades. Typical recycled content is 60%.
Manufacturability5
E309Nb PWHT's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability excellent (85/100); formability fair (38/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E309Nb PWHT
Is E309Nb easy to machine?
Deposit machines like an austenitic stainless with hard ferrite/NbC particles — use sharp carbide, positive rake, low speed, heavy feed and flood coolant to avoid work hardening.
Can E309Nb be welded?
Use short arc, low heat input and stringer beads; DCEP (AC also for -16/-17/-26), interpass below ~150 °C, and redry electrodes per the maker (typically 250–300 °C for basic types) before use.
Can E309Nb be formed, bent or molded?
Not a wrought product; deposit is ductile enough for weld dressing and light peening but should not be cold-formed as a structural section.
What surface finishes work on E309Nb?
Pickle and passivate or mechanically clean the slag/heat tint; the ferrite makes the bead magnetically detectable and slightly harder to polish to a mirror finish than fully austenitic deposits.
E309Nb 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 A5.4 undiluted weld metal | ≤ 0.12 | 0.06 |
| Cr | 22 – 25 | 23.5 |
| Ni | 12 – 14 | 13 |
| NbNb+Ta (Cb+Ta), stabilizer | 0.7 – 1 | 0.85 |
| Mn | 0.5 – 2.5 | 1.5 |
| Si | ≤ 0.9 | 0.6 |
| Moresidual | ≤ 0.75 | 0.15 |
| Curesidual | ≤ 0.75 | 0.1 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Fe | balance | — |
E309Nb PWHT — frequently asked
What is E309Nb PWHT used for?
E309Nb PWHT is typically used for dissimilar metal welding, carbon-to-stainless transition joints, cladding/overlay on carbon steel and buffer layers before stainless overlay. In short: nb-stabilized dissimilar-metal electrode; standard buffer-layer filler; resists carbide precipitation.
What is the yield strength of E309Nb PWHT?
E309Nb PWHT has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 2 listed tempers.
Is E309Nb PWHT easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% of stainless steel grades). Deposit machines like an austenitic stainless with hard ferrite/NbC particles — use sharp carbide, positive rake, low speed, heavy feed and flood coolant to avoid work hardening.
Can E309Nb PWHT be welded?
Yes — weldability is rated excellent (85/100). Use short arc, low heat input and stringer beads; DCEP (AC also for -16/-17/-26), interpass below ~150 °C, and redry electrodes per the maker (typically 250–300 °C for basic types) before use.
What surface finishes work on E309Nb PWHT?
Pickle and passivate or mechanically clean the slag/heat tint; the ferrite makes the bead magnetically detectable and slightly harder to polish to a mirror finish than fully austenitic deposits.
Can E309Nb PWHT be formed, bent or molded?
Not a wrought product; deposit is ductile enough for weld dressing and light peening but should not be cold-formed as a structural section.
What is the maximum service temperature of E309Nb PWHT?
E309Nb PWHT is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E309Nb-AW and E309Nb PWHT?
AW is the default condition — default condition for dissimilar-metal joints and buffer layers; use as-deposited unless the base metal demands PWHT. PWHT: condition after the joint is stress-relieved with the ferritic base metal; Nb stabilization keeps the deposit sensitization-free but ferrite may partly transform, lowering toughness. Yield strength is 420 MPa in AW versus 400 MPa in PWHT.
Sources
- AWS A5.4/A5.4M — Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding — American Welding Society (2012)
- ASME BPVC Section II Part C — SFA-5.4 — ASME (2023)
- 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)
- Stainless SMAW electrode datasheets (309Nb/309Cb types) — 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.