Stainless Steel E309LMo PWHT
Heat-treated state
UNS W30923 · ASTM A5.4
PWHT = post-weld heat treated
Applies when the C-steel/low-alloy component must be stress relieved; expect some ferrite transformation, slight strength gain and toughness loss.
Values for the PWHT condition
Other E309LMo tempers and conditions
E309LMo is listed in 5 conditions; see the grade overview at E309LMo.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Silica-boosted rutile coating, AC or DCEP | Choose for the flattest, best-wetting bead on flat/horizontal fillets and overlay; more fluid slag than -16, slightly softer arc. | 420 | 590 | 38 | 185 HB | 2.2 % IACS |
AWDefault As-welded deposit | Default condition for dissimilar joints and buttering layers; deposit used directly after welding with 8–20 FN ferrite. | 430 | 600 | 36 | 190 HB | 2.2 % IACS |
Titania (rutile) coating, AC or DCEP | Most widely stocked coating type: smooth arc, easy slag removal, AC/DC operation for general shop and site welding. | 430 | 600 | 36 | 190 HB | 2.2 % IACS |
PWHTThis page Post-weld heat treated | Applies when the C-steel/low-alloy component must be stress relieved; expect some ferrite transformation, slight strength gain and toughness loss. | 440 | 610 | 30 | 200 HB | 2.2 % IACS |
Lime (basic) coating, DCEP only | Pick for out-of-position work and where the cleanest, lowest-hydrogen, toughest deposit is required; DC electrode positive only. | 450 | 610 | 35 | 195 HB | 2.2 % IACS |
What is E309LMo PWHT?
E309LMo PWHT is E309LMo heat treated to PWHT — applies when the C-steel/low-alloy component must be stress relieved; expect some ferrite transformation, slight strength gain and toughness loss. E309LMo PWHT has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 68% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 197 GPa (28.6 Msi). E309LMo 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
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
E309LMo PWHT properties
Typical room-temperature values for E309LMo PWHT; 22 are specific to this condition. Other listed values are E309LMo reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
E309LMo 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
E309LMo PWHT has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 68% of stainless steel grades. Elongation at break is 30% and the elastic modulus is 197 GPa (28.6 Msi).
Thermal6
E309LMo PWHT is rated for continuous service to 400°C (752 °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
E309LMo PWHT conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of E309LMo PWHT takes about 55 MJ of energy and emits 5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability6
E309LMo PWHT's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability excellent (85/100); formability poor (32/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E309LMo PWHT
Is E309LMo easy to machine?
Weld deposit machines like 316L — gummy and strongly work-hardening; use sharp carbide, positive rake, heavy feed and flood coolant, avoid dwelling.
Can E309LMo be welded?
SMAW with DCEP (AC also for -16/-17), short arc, stringer beads, interpass ≤150 °C; redry electrodes ~250–300 °C/1 h and keep ferrite 8–20 FN to avoid hot cracking.
Can E309LMo be formed, bent or molded?
Not a wrought product; deposited overlay can be lightly ground/peened but not cold formed as such.
What surface finishes work on E309LMo?
Grind, pickle (HNO₃-HF paste) and passivate the deposit to restore the passive film; deposit is weakly magnetic so magnetic-particle testing is unreliable — use PT/UT.
E309LMo 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 |
|---|---|---|
| Clow-carbon 'L' grade | ≤ 0.04 | 0.03 |
| Cr | 22 – 25 | 23.5 |
| Ni | 12 – 14 | 13 |
| Mo | 2 – 3 | 2.5 |
| Mn | 0.5 – 2.5 | 1.3 |
| Sihigher end in -17 coating types | ≤ 0.9 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cu | ≤ 0.75 | 0.1 |
| Fe | balance | — |
E309LMo PWHT — frequently asked
What is E309LMo PWHT used for?
E309LMo PWHT is typically used for 316L to carbon steel transitions, clad/overlay welding on pressure vessels and chemical processing equipment. In short: standard 316L-to-steel filler; most corrosion-resistant 309 type; low-carbon overlay electrode.
What is the yield strength of E309LMo PWHT?
E309LMo PWHT has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 610 MPa (88.5 ksi) — stronger than 68% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is E309LMo PWHT easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Weld deposit machines like 316L — gummy and strongly work-hardening; use sharp carbide, positive rake, heavy feed and flood coolant, avoid dwelling.
Can E309LMo PWHT be welded?
Yes — weldability is rated excellent (85/100). SMAW with DCEP (AC also for -16/-17), short arc, stringer beads, interpass ≤150 °C; redry electrodes ~250–300 °C/1 h and keep ferrite 8–20 FN to avoid hot cracking.
What surface finishes work on E309LMo PWHT?
Grind, pickle (HNO₃-HF paste) and passivate the deposit to restore the passive film; deposit is weakly magnetic so magnetic-particle testing is unreliable — use PT/UT.
Can E309LMo PWHT be formed, bent or molded?
Not a wrought product; deposited overlay can be lightly ground/peened but not cold formed as such.
What is the maximum service temperature of E309LMo PWHT?
E309LMo PWHT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E309LMo-AW and E309LMo PWHT?
AW is the default condition — default condition for dissimilar joints and buttering layers; deposit used directly after welding with 8–20 FN ferrite. PWHT: applies when the C-steel/low-alloy component must be stress relieved; expect some ferrite transformation, slight strength gain and toughness loss. Yield strength is 430 MPa in AW versus 440 MPa in PWHT.
Sources
- AWS A5.4/A5.4M — Stainless Steel Electrodes for Shielded Metal Arc Welding — American Welding Society (2012)
- ASME BPVC Section II Part C, SFA-5.4 — ASME (2023)
- EN ISO 3581 — Covered electrodes for manual metal arc welding of stainless and heat-resisting steels — ISO/CEN (2016)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Stainless SMAW consumable datasheets (ESAB / Böhler / Lincoln 309LMo types) — various (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.