AWS Class E309LMo-16 Welding Electrodes

E309LMo-16 Stainless Steel Welding Electrode Supplier & Stockist in Mumbai, India — AWS A5.4 UNS W30923

Name: AWS Class E309LMo-16 Welding Electrodes
Brand: Nicorex Alloys

Nicorex Alloys is an ISO 9001 and ISO 14001 certified importer, stockist, and supplier of E309LMo-16 coated welding electrodes based in Mumbai, India. We provide these E309LMo-16 SS welding electrodes as classified under AWS A5.4 / ASME SFA 5.4 for shielded metal arc welding (SMAW).

Also recognised as E309MoL-16, Oxford Alloy 309LMo-16, ESAB OK 67.75, Lincoln Excalibur 309LMo-16, Böhler FOX EAS 4 M-A, Kobelco NC-39Mo, and UNS W30923, this is a Mo-bearing austenitic stainless steel covered electrode. The “-16” suffix indicates a titania (rutile) coating suitable for AC and DCEP polarity with all-position capability. E309LMo-16 deposits contain 2.0–3.0% Mo. When the first weld pass on carbon steel dilutes approximately 30–40% base metal into the deposit, E309LMo-16 retains enough Mo (1.2–1.8%) for good pitting resistance. The Mo content makes E309LMo-16 the mandatory first-layer electrode for 316L-type weld overlay cladding on carbon steel, the required consumable for welding 316/316L clad steel plate, and the preferred choice for dissimilar joints between 316L stainless and carbon or low-alloy steel. The deposit composition of 23Cr-13Ni-2.5Mo-0.03C produces 8–15 Ferrite Number (FN) due to molybdenum’s ferrite-promoting effect, which improves solidification cracking resistance.

Available diameters span from 2.5 to 5.0 mm (3/32” to 3/16”), and dissimilar joints must not exceed 315°C (600°F) in continuous service to prevent carbon migration. Key industries include petrochemical & chemical processing, pharmaceutical & food processing, pulp & paper, and other industries covered below. Every batch is shipped with EN 10204/3.1B mill test certificates, PMI reports, and traceability documentation. Contact Nicorex Alloys for stock availability and pricing.

E309LMo-16 Coated Electrode Specifications

The E309LMo-16 specifications, including AWS classification, UNS number, welding process and position, polarity, and other key details, are covered in the table below:

AWS Classification	E309LMo-16
ASME SFA Specification	SFA 5.4
UNS Number	W30923
Welding Process	SMAW (Shielded Metal Arc Welding)
Electrode Coating	Titania (rutile) — the “-16” designation
Current / Polarity	AC or DCEP (DC Electrode Positive)
Welding Positions	All positions (F, V-up, V-down, OH, H)
Available Diameters (mm)	2.5, 3.15, 4.0, 5.0 (mm) 3/32, 1/8, 5/32, 3/16 (inches)
Electrode Length	300 mm (12”) for 2.5 mm; 350 mm (14”) for 3.15 mm and above

Weld Deposit Chemical Composition of E309LMo-16

The table below presents all-weld-metal chemistry as per AWS A5.4. The key alloying elements are covered in detail below:

Standard	C	Cr	Ni	Mo	Mn	Si	P	S	Cu
AWS A5.4 Range (wt.%)	0.04 max	22.0–25.0	12.0–14.0	2.0–3.0	0.5–2.5	1.0 max	0.04 max	0.03 max	0.75 max

Chromium at 22–25% and nickel at 12–14% are deliberately higher than 316L base metal to compensate for 30–40% carbon steel dilution. When E309LMo-16 is deposited on carbon steel, approximately 30–40% of the weld pool is diluted base metal (essentially Fe with negligible Cr/Ni/Mo). The overalloyed 309LMo composition is deliberately designed so that after this dilution, the resulting mixed deposit has 316 stainless steel equivalent chemistry (~17Cr-12Ni-2Mo). Standard E309L (no Mo) deposits produce a first pass that resembles 304 rather than 316 after dilution — lacking pitting resistance. The 0.04% carbon limit prevents Cr₂₃C₆ grain boundary precipitation (sensitisation).

PREN comparison: E309LMo undiluted ≈ 30–33; after 35% CS dilution ≈ 23–25 (316L equivalent). E309L after dilution ≈ 16–18 (304 equivalent, no pitting resistance). Actual values vary with welding parameters and dilution.

All-Weld-Metal Mechanical Properties of E309LMo-16

The mechanical properties of E309LMo-16, including tensile and yield strength, elongation, ferrite number, and other key properties, are provided in the table below:

Condition	Tensile Strength	Yield Strength, 0.2% Offset	Elongation	Ferrite Number	Side Bend Test	Charpy V-Notch Impact
Typical Value	~620 MPa (90 ksi)	~440 MPa (64 ksi)	~40%	8–15 FN (WRC-1992)	Required — pass without cracking	Not specified
AWS A5.4 Minimum	520 MPa (75 ksi)	Not specified	30%	Not specified	As per AWS A5.4	Not specified

The 2–3% Mo adds solid-solution strengthening, giving E309LMo deposits approximately 10–15% higher tensile strength than standard E309L (~550 MPa). The 8–15 FN ferrite content improves hot cracking resistance but can embrittle above 475°C with prolonged exposure, reinforcing the 315°C service limit.

Base Metal Compatibility and P-Number Matrix for E309LMo-16

E309LMo-16 (F-4, A-8) is primarily a dissimilar/transition electrode. For 304/304L to carbon steel, use E309L-16 (Mo not needed). For 316L-to-316L similar joints, use E316L-16.

Base Metal A	Spec / UNS	P-No. A	Base Metal B	P-No. B	Joint Type	Notes
316/316L	P-8, Gr.1	P-8	CS (SA-516/SA-106)	P-1	Dissimilar	Primary application
316/316L	P-8	P-8	Low-Alloy (SA-387)	P-4/P-5A	Dissimilar	Service <315°C
316 Clad Steel	SA-264	P-1 + clad	—	—	Clad side weld	E309LMo-16 at interface
Overlay Layer 1	—	—	Carbon Steel	P-1	CRA overlay	E309LMo-16 first pass
Overlay Layer 2+	—	—	On Layer 1	—	CRA overlay	E316L-16 cap passes
304/304L to CS	—	—	—	—	Not recommended	Use E309L-16 instead
316L to 316L	—	—	—	—	Not recommended	Use E316L-16 (matching)

Recommended Welding Parameters for E309LMo-16 Electrode

The recommended welding parameters for the E309LMo-16 electrode based on dimensions and polarity are provided below:

Diameter (mm)	Diameter (in)	Length (mm)	Length (in)	Current (A)	Polarity	Position	Best For
2.5	3/32	300	12	50–80	AC/DCEP	All	Root passes, thin sheet, all-position pipe
3.15	1/8	350	14	80–120	AC/DCEP	All	General purpose — clad steel and dissimilar joints
4.0	5/32	350	14	110–160	AC/DCEP	All	Fill passes, plate >8 mm, overlay flat position
5.0	3/16	350	14	140–200	AC/DCEP	F, H	Heavy plate, large-area overlay cladding

Maximum interpass temperature is 150°C (300°F) for austenitic stainless deposits. Preheat is not required for stainless steel; for thick carbon steel (>25 mm), apply 100–150°C on the CS side only. Avoid PWHT for dissimilar joints. Heating above 600°C causes carbon migration. Argon back-purge root passes on pipe welds.

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Industries & Welding Applications of E309LMo-16 Electrodes

E309LMo-16 serves as the essential transition electrode wherever 316-grade stainless steel interfaces with carbon steel. The molybdenum content keeps pitting resistance intact in the dilution-affected first weld pass across petrochemical, pharmaceutical, food processing, marine, and pulp and paper sectors.

Weld 316/316L nozzles and internals to SA-516 Gr.70 carbon steel vessel shells in reactors and heat exchangers. Handles dissimilar butt joints between 316L piping and A106 Gr.B carbon steel at process transitions.
Pharmaceutical reactors, WFI systems, and food-contact surfaces. E309LMo-16 is required wherever these connect to carbon steel supports, saddles, or nozzle pads.
Kraft pulp digesters and bleach plant washers. E309LMo-16 welds the clad side and dissimilar transitions.
E309LMo-16 provides the first layer for 316L overlay on condenser tubesheets in coastal power plants, resisting seawater chloride pitting. It also handles dissimilar joints in FGD scrubber components and marine transitions.
E309LMo-16 is the mandatory first-layer electrode for 316L-type CRA weld overlay on carbon steel: Layer 1 = E309LMo-16 (compensates for iron dilution); Layer 2+ = E316L-16 (undiluted 316L for service exposure).

Storage, Handling, and Re-Drying Procedures for E309LMo-16 Electrodes

Electrodes from unopened vacuum-sealed packets do not need re-drying. After opening, store in a holding oven at 100–150°C (212–300°F). If exposed to humidity beyond 4 hours, re-bake at 250–300°C (480–570°F) for 1–2 hours, limiting to 3 cycles. Avoid carbon steel tooling. Use dedicated stainless steel brushes and grinding discs. Free iron contamination creates rust initiation sites, a GMP violation in pharmaceutical and food-contact work.

Available Sizes of E309LMo-16 Stick Electrode

Nicorex Alloys stocks all four diameters in vacuum-sealed packets with full MTC documentation. The titania coating produces a smooth, stable arc with self-releasing slag, well-suited for positional work.

Diameter (in)	Diameter (mm)	Length (in)	Length (mm)	Current (A) AC/DCEP
3/32	2.50	12	300	50–80
1/8	3.15	14	350	80–120
5/32	4.00	14	350	110–160
3/16	5.00	14	350	140–200

How to Order E309LMo-16 Stainless Steel Welding Electrodes from Nicorex Alloys

To place an order for E308L-16 / E308H-16 welding electrodes from Nicorex Alloys, provide the following details:

Electrode Type: SMAW; AWS A5.4 / ASME SFA-5.4: E309LMo-16
Size: 2.4 mm, 3.2 mm, 4.0 mm, 4.8 mm; electrodes
Current Type: DCEP or AC
Welding Position: All positions (1G, 2G, 3G, 4G, 6G)
Material Grade: 309LMo; UNS S38820; W.Nr. 1.4459; EN ISO 3581-A: E 23 12 2 L R
Quantity: Specify number of cans or total kg required
Standard: AWS A5.4 / ASME SFA-5.4; EN ISO 3581; ASME Section IX
Documentation: MTC EN 10204 3.1/3.2; FN Report; NACE MR0175; TPI certificate
Packaging: Hermetically sealed metal cans; ISPM 15 compliant export cartons
Delivery Destination: Domestic / International; specify port or delivery address

Do not accept E309L-16 as a substitute for 316-type overlay or clad steel welding. Common diameters ship from ready stock. Contact Nicorex Alloys for competitive pricing.

Frequently Asked Questions

What is the Difference Between E309LMo-16 and E309L-16?

The only difference is molybdenum. E309LMo-16 contains 2.0–3.0% Mo; E309L-16 allows 0.75% max (typically <0.3%). After 30–40% dilution on carbon steel, E309LMo-16 retains 1.2–1.8% Mo for 316-equivalent pitting resistance. E309L-16 produces a deposit resembling 304 stainless steel with no pitting resistance.

Why is E309LMo-16 Required as the First Layer for 316L Weld Overlay on Carbon Steel?

The first pass dilutes 30–40% carbon steel into the deposit, reducing Cr, Ni, and Mo. E309LMo-16 starts with 22–25% Cr, 12–14% Ni, and 2–3% Mo. After 35% dilution, the deposit retains ~17% Cr, ~8.5-9% Ni, and ~1.5% Mo (316-equivalent). E309L (no Mo) produces a diluted pass with virtually zero Mo, failing 316 corrosion requirements. The second layer (E316L-16) is undiluted and matches 316L directly.

What does the ‘-16’ Suffix Mean in E309LMo-16?

In AWS A5.4, the suffix indicates coating type: The “-16” suffix means a titania/rutile (AC or DCEP, smooth arc, easy slag removal, all-position).

What Ferrite Number does E309LMo-16 Produce, and Why does it Matter?

E309LMo-16 produces 8–15 FN as per the WRC-1992 diagram, which is higher than E309L (5–10 FN) because Mo promotes ferrite. A minimum of 5 FN prevents solidification cracking, while excessive ferrite above 15 FN reduces corrosion performance and risks 475°C embrittlement. Many specifications require a defined range (e.g., 5–12 FN) — verify against your WPS.