Stainless Steel E409Nb PWHT
Heat-treated state
UNS W40910
PWHT = post-weld heat treated
Choose when maximum weld-metal ductility, toughness and dimensional stability are needed on thicker sections.
Values for the PWHT condition
Other E409Nb tempers and conditions
E409Nb is listed in 5 conditions; see the grade overview at E409Nb.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PWHTThis page Post-weld heat treated | Choose when maximum weld-metal ductility, toughness and dimensional stability are needed on thicker sections. | 330 | 470 | 26 | 160 HB | 3 % IACS |
E409Nb-17 | Pick for the finest bead appearance and fluid slag on flat/horizontal fillets in sheet-metal exhaust work. | 375 | 495 | 22 | 176 HB | 2.9 % IACS |
AWDefault As-welded deposit | Standard condition for thin-gauge exhaust and automotive fabrication where no PWHT is applied. | 380 | 500 | 22 | 180 HB | 2.9 % IACS |
E409Nb-16 | Most widely stocked coating type: smooth arc, easy slag removal, all-position on thin exhaust sheet with AC or DC+ power sources. | 380 | 500 | 22 | 180 HB | 2.9 % IACS |
E409Nb-15 | Use where lowest hydrogen and best weld-metal toughness/crack resistance are required on restrained or thicker joints. | 390 | 505 | 23 | 183 HB | 2.9 % IACS |
What is E409Nb PWHT?
E409Nb PWHT is E409Nb heat treated to PWHT — choose when maximum weld-metal ductility, toughness and dimensional stability are needed on thicker sections. E409Nb PWHT has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 57% of stainless steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi). E409Nb PWHT has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,480°C (2,696 °F). AW is the default condition FabDigit quotes; PWHT is available on request or by drawing note.
Advantages
- Conducts heat well — 25.5 W/m·K (14.7 BTU/hr·ft·°F), better than 95% of stainless steel grades
- High electrical conductivity — 3 % IACS, better than 95% of stainless steel grades
- Easy to machine — 55/100, better than 94% of stainless steel grades
- Low embodied carbon — 3.8 kg CO₂/kg, better than 77% of stainless steel grades
Limitations
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 91% of stainless steel grades
- Hard to polish — 55/100, worse than 89% of stainless steel grades
- Needs corrosion protection — 48/100, worse than 80% of stainless steel grades
E409Nb PWHT properties
Typical room-temperature values for E409Nb PWHT; 22 are specific to this condition. Other listed values are E409Nb reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
E409Nb PWHT has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,480°C (2,696 °F).
Mechanical16
E409Nb PWHT has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 57% of stainless steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
E409Nb PWHT is rated for continuous service to 675°C (1,247 °F). It conducts heat at 25.5 W/m·K (14.7 BTU/hr·ft·°F), better than 95% of stainless steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
E409Nb PWHT conducts electricity at 3 % IACS, better than 95% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of E409Nb PWHT takes about 52 MJ of energy and emits 3.8 kg of CO₂ — less than 76% of stainless steel grades. Typical recycled content is 65%.
Manufacturability6
E409Nb PWHT's machinability is good (55/100, better than 94% of stainless steel grades); weldability very good (70/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E409Nb PWHT
Is E409Nb easy to machine?
Weld deposit machines like Type 409 — moderate rating (~55% of AISI 1212); use sharp carbide, rigid setup and positive rake to avoid work-hardened smearing.
Can E409Nb be welded?
Redry electrodes per maker's schedule, use low heat input and stringer beads, interpass below ~150 °C to limit ferrite grain coarsening; 150–250 °C preheat helps on thick or restrained sections.
Can E409Nb be formed, bent or molded?
Deposit is fully ferritic with limited ductility — avoid tight-radius cold forming across the weld; form the sheet before welding where possible.
What surface finishes work on E409Nb?
Grind and pickle/passivate to restore the chromium oxide film; the deposit takes a fair mechanical polish but will rust-stain if free iron or heat tint remains.
E409Nb 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 | ≤ 0.12 | 0.06 |
| Cr | 11 – 14 | 12.5 |
| Ni | ≤ 0.6 | 0.3 |
| Mn | ≤ 1 | 0.6 |
| Si | ≤ 1 | 0.6 |
| Nbcolumbium, stabilizer | 0.5 – 1.5 | 0.9 |
| Mo | ≤ 0.75 | — |
| Cu | ≤ 0.75 | — |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
E409Nb PWHT — frequently asked
What is E409Nb PWHT used for?
E409Nb PWHT is typically used for automotive exhaust systems, mufflers and catalytic converter shells, heat exchanger tubing repair and mild corrosive service parts. In short: low-cost exhaust-grade filler; stabilized against weld decay; ferritic, limited weld ductility.
What is the yield strength of E409Nb PWHT?
E409Nb PWHT has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 57% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is E409Nb PWHT easy to machine?
Reasonably — machinability is rated good (55/100, better than 94% of stainless steel grades). Weld deposit machines like Type 409 — moderate rating (~55% of AISI 1212); use sharp carbide, rigid setup and positive rake to avoid work-hardened smearing.
Can E409Nb PWHT be welded?
Yes — weldability is rated very good (70/100). Redry electrodes per maker's schedule, use low heat input and stringer beads, interpass below ~150 °C to limit ferrite grain coarsening; 150–250 °C preheat helps on thick or restrained sections.
What surface finishes work on E409Nb PWHT?
Grind and pickle/passivate to restore the chromium oxide film; the deposit takes a fair mechanical polish but will rust-stain if free iron or heat tint remains.
Can E409Nb PWHT be formed, bent or molded?
Deposit is fully ferritic with limited ductility — avoid tight-radius cold forming across the weld; form the sheet before welding where possible.
What is the maximum service temperature of E409Nb PWHT?
E409Nb PWHT is rated for continuous use to about 675°C (1,247 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E409Nb-AW and E409Nb PWHT?
AW is the default condition — standard condition for thin-gauge exhaust and automotive fabrication where no PWHT is applied. PWHT: choose when maximum weld-metal ductility, toughness and dimensional stability are needed on thicker sections. Yield strength is 380 MPa in AW versus 330 MPa in PWHT.
Sources
- AWS A5.4/A5.4M — Stainless Steel Electrodes for Shielded Metal Arc Welding — American Welding Society (2012)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (Type 409) — ASM International (1990)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (ferritic stainless weldability) — ASM International (1993)
- Ferritic stainless SMAW electrode datasheets (409/409Nb class) — Welding consumable producers (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.