Stainless Steel E309Mo
UNS W30920 · ASTM A5.4
E309Mo is a standard-carbon 309-type austenitic stainless covered electrode to AWS A5.4 (UNS W30920) with a molybdenum addition.
Reference datasheet — E309Mo is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AW condition
E309Mo tempers and conditions
E309Mo is supplied in 3 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
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 |
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?
E309Mo is a standard-carbon 309-type austenitic stainless covered electrode to AWS A5.4 (UNS W30920) with a molybdenum addition. It is applied like E309LMo for dissimilar-metal welds and overlay cladding on Mo-bearing base metals where the higher carbon level is acceptable, and it gives about 450 MPa yield, 600 MPa tensile, 32 % elongation and 200 HB as welded, with service to roughly 750 °C. The higher carbon reduces resistance to sensitisation, so E309LMo is the nearer choice for wet corrosive or as-welded chloride service. E309Mo 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). E309Mo has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 70% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 196 GPa (28.4 Msi).
What is E309Mo used for?
- dissimilar metal welding with Mo-bearing base metals
- overlay cladding
- process equipment fabrication
Advantages
- Readily welded — 80/100, better than 80% of stainless steel grades
Limitations
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
E309Mo properties
Typical room-temperature values for E309Mo-AW; bars are the position among stainless steel grades.
Physical3
E309Mo 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 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 70% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 196 GPa (28.4 Msi).
Thermal6
E309Mo is rated for continuous service to 750°C (1,382 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
E309Mo conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 59% of stainless steel grades.
Sustainability4
Producing a kilogram of E309Mo 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's machinability is poor (32/100, worse than 62% of stainless steel grades); weldability very good (80/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. E309Mo is highlighted; hover a dot for its name, or open the interactive family chart.
Working with E309Mo
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.
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 |
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.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel E309Mo in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- W30920
- ASTM
- A5.4
How much does E309Mo cost?
E309Mo is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
E309Mo — frequently asked
What is E309Mo used for?
E309Mo 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?
E309Mo has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 70% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is E309Mo easy to machine?
Not especially — machinability is rated poor (32/100, worse than 62% 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 be welded?
Yes — weldability is rated very good (80/100). 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?
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 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?
E309Mo 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.
How much does E309Mo cost?
E309Mo is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.