Stainless Steel E309Mo PWHT
Heat-treated state
UNS W30920 · ASTM A5.4
PWHT = post-weld heat treated
Used when the carbon-steel side of a dissimilar joint mandates code stress relief; accept lower toughness and sensitisation risk.
Values for the PWHT condition
Other E309Mo tempers and conditions
E309Mo is listed in 3 conditions; see the grade overview at E309Mo.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed (~1050 °C + rapid cool) weld deposit | Only for weldments (e.g. clad or overlaid components) that are solution annealed as a whole to restore corrosion resistance and ductility. | 350 | 570 | 38 | 175 HB | 2.3 % IACS |
PWHTThis page Post-weld heat treated | Used when the carbon-steel side of a dissimilar joint mandates code stress relief; accept lower toughness and sensitisation risk. | 430 | 590 | 28 | 195 HB | 2.3 % IACS |
AWDefault As-welded deposit | Standard qualification/service condition for E309Mo electrodes; use for dissimilar joints and 316-type overlay buffer layers. | 450 | 600 | 32 | 200 HB | 2.2 % IACS |
What is E309Mo PWHT?
E309Mo PWHT is E309Mo heat treated to PWHT — used when the carbon-steel side of a dissimilar joint mandates code stress relief; accept lower toughness and sensitisation risk. E309Mo PWHT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 196 GPa (28.4 Msi). E309Mo 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.
Limitations
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- Low fracture toughness — 85 MPa·√m (77.4 ksi·√in), worse than 77% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
E309Mo PWHT properties
Typical room-temperature values for E309Mo PWHT; 22 are specific to this condition. Other listed values are E309Mo reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
E309Mo 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
E309Mo PWHT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
E309Mo PWHT is rated for continuous service to 750°C (1,382 °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
E309Mo PWHT conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of E309Mo PWHT takes about 60 MJ of energy and emits 5.5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 40%.
Manufacturability7
E309Mo PWHT's machinability is poor (34/100, worse than 55% of stainless steel grades); weldability very good (78/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E309Mo PWHT
Is E309Mo easy to machine?
Weld deposit machines like 316-type stainless: low speeds, positive-rake sharp carbide, heavy rigid setup and flood coolant to fight work hardening and gumminess.
Can E309Mo be welded?
SMAW with DCEP (E309Mo-15/-16 also run AC for -16); redry electrodes 250–300 °C, keep interpass below ~150 °C on dissimilar joints, use stringer beads and maintain 10–20 FN ferrite to avoid hot cracking.
Can E309Mo be formed, bent or molded?
Not a wrought product — deposit geometry is set by bead placement; buffer layers of 2–3 mm are typical before depositing 316-type surfacing.
What surface finishes work on E309Mo?
Remove slag fully between passes, then pickle/passivate or blast-and-brush with stainless tooling; do not anodise, and avoid carbon-steel wire brushes that cause iron contamination.
E309Mo 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 |
|---|---|---|
| Cstandard carbon (vs 0.04 max for E309LMo) | ≤ 0.12 | 0.06 |
| Cr | 22 – 25 | 23.5 |
| Ni | 12 – 14 | 13 |
| Mo | 2 – 3 | 2.5 |
| Mn | 0.5 – 2.5 | 1.5 |
| Si | ≤ 0.9 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cu | ≤ 0.75 | 0.1 |
| Febalance, undiluted weld metal | balance | — |
E309Mo PWHT — frequently asked
What is E309Mo PWHT used for?
E309Mo PWHT is typically used for dissimilar metal welding with Mo-bearing base metals, overlay cladding and process equipment fabrication. In short: standard-carbon 309Mo electrode; buffer layer for 316 overlay; higher strength than E309LMo.
What is the yield strength of E309Mo PWHT?
E309Mo PWHT has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is E309Mo PWHT easy to machine?
Not especially — machinability is rated poor (34/100, worse than 55% of stainless steel grades). Weld deposit machines like 316-type stainless: low speeds, positive-rake sharp carbide, heavy rigid setup and flood coolant to fight work hardening and gumminess.
Can E309Mo PWHT be welded?
Yes — weldability is rated very good (78/100). SMAW with DCEP (E309Mo-15/-16 also run AC for -16); redry electrodes 250–300 °C, keep interpass below ~150 °C on dissimilar joints, use stringer beads and maintain 10–20 FN ferrite to avoid hot cracking.
What surface finishes work on E309Mo PWHT?
Remove slag fully between passes, then pickle/passivate or blast-and-brush with stainless tooling; do not anodise, and avoid carbon-steel wire brushes that cause iron contamination.
Can E309Mo PWHT be formed, bent or molded?
Not a wrought product — deposit geometry is set by bead placement; buffer layers of 2–3 mm are typical before depositing 316-type surfacing.
What is the maximum service temperature of E309Mo PWHT?
E309Mo PWHT is rated for continuous use to about 750°C (1,382 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E309Mo-AW and E309Mo SOL-ANN?
AW is the default condition — standard qualification/service condition for E309Mo electrodes; use for dissimilar joints and 316-type overlay buffer layers. SOL-ANN: only for weldments (e.g. clad or overlaid components) that are solution annealed as a whole to restore corrosion resistance and ductility. Yield strength is 450 MPa in AW versus 350 MPa in SOL-ANN.
Sources
- AWS A5.4/A5.4M — Stainless Steel Electrodes for Shielded Metal Arc Welding — American Welding Society (2012)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- 309Mo-type covered electrode datasheets (Böhler, ESAB, Lincoln Electric) — voestalpine 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.