AWS A5.9 / ASME SFA-5.9 · Stainless MIG wire & TIG rod (GMAW / GTAW)

ER309L Dissimilar Metal Wire and TIG Rod

ER309L is an over-alloyed, extra-low-carbon austenitic stainless steel bare wire or rod classified to AWS A5.9 for welding stainless steel to carbon and low-alloy steel, for buttering and cladding, and for welding 24 % chromium, 13 % nickel materials, carrying deliberately high chromium and nickel so the deposit remains austenitic after being diluted by the carbon steel side of the joint.

Dissimilar joints, stainless to carbon steel, cladding and buttering
Stainless MIG wire & TIG rod (GMAW / GTAW)
EN ISO 14343-A
6 ESAB grades

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Price on request. POFIS is an ESAB Authorized Distributor & Service Centre in Abu Dhabi — quotations include confirmed lead time and delivery terms.

The designation

What ER309L / ER309LSi / ER309LMo means

ER: A bare electrode or rod under AWS A5.9, fed as MIG wire or cut as TIG rod. The covered stick electrode equivalent is E309L under AWS A5.4.
309: Nominally 24 % chromium and 13 % nickel — substantially richer than the 304 or 316 it usually welds. That excess is the entire point of the alloy.
L: Extra low carbon, limiting chromium carbide precipitation and the intergranular corrosion that follows. Important here because a dissimilar joint already carries enough metallurgical complication.
Si: The high-silicon variant, for better wetting and a flatter bead. Particularly useful on cladding and surfacing passes, where bead shape determines how many passes are needed to cover an area.
Mo: ER309LMo adds roughly 3 % molybdenum. Specify it when the stainless side of the joint is 316 or 316L, so the pitting resistance that side was chosen for carries through the weld. Plain ER309L has none.

Reading the ER309L / ER309LSi / ER309LMo designation, left to right.

How it behaves

ER309L / ER309LSi / ER309LMo in practice

Dilution is the problem this alloy solves

When stainless is welded to carbon steel the molten pool takes metal from both sides. ESAB puts MIG and MAG dilution at 25 to 40 % and TIG with filler at 20 to 40 %. A matching 308L or 316L deposit diluted by a third with plain carbon steel falls short of the chromium and nickel needed to stay austenitic, and can solidify partly martensitic — hard, brittle and liable to crack. ER309L starts rich enough to survive that dilution and still finish austenitic.

Process choice changes the answer

Because dilution varies by process, the same consumable behaves differently depending on how it is applied. Stick welding pulls 15 to 30 %; MIG and MAG 25 to 40 %; TIG with filler 20 to 40 %; and autogenous TIG 100 %, which means no composition control at all. On a dissimilar joint the wire processes dilute harder than stick, so technique matters more: lower current, stringer beads, small diameters, high travel speed, and keeping the arc off the ferritic parent.

Match the molybdenum to the stainless side

If the stainless side is 316 or 316L, plain ER309L leaves the joint with no molybdenum and therefore no pitting resistance where the 316L was specified to provide it. ER309LMo exists for that case, at roughly 22 % Cr, 15 % Ni and 3 % Mo. The rule is that the deposit should carry whatever the stainless side was chosen for, after allowing for dilution — which usually means over-alloying on that axis too.

Ferrite is higher here, and sometimes specified

An over-alloyed deposit carries more ferrite than a matching one. ESAB publishes approximately 8 to 10 % for the standard grades, and Exaton 24.13.LHF is a deliberately high-ferrite grade at approximately 14 %. On cladding rather than a one-off joint, the ferrite in the finished surface is usually specified and measured, so agree the acceptance range before welding starts — it is set by the client specification rather than by the consumable.

The 300 °C service limit still applies

Austenitic consumables in a heterogeneous joint are limited to 300 °C service with no post-weld heat treatment, because above that chromium carbides precipitate at the grain boundaries and deplete the grains of chromium. That ceiling is a property of the consumable family, not of the form — it applies to ER309L wire exactly as it does to E309L electrodes. Above 300 °C, a nickel-based filler such as Alloy 82 is required instead.

What POFIS supplies

ESAB ER309L / ER309LSi / ER309LMo grades

Every grade below carries the ER309L / ER309LSi / ER309LMo classification, which is why a WPS naming ER309L / ER309LSi / ER309LMo can be satisfied by any of them. They are not interchangeable in practice — the differences in current type, hydrogen level and impact toughness are what decide which one belongs on your job. Figures are the manufacturer's typical as-welded values.

**ER309L / ER309LSi / ER309LMo grades supplied by POFIS** — typical as-welded properties. Blank cells are values the manufacturer does not publish for that grade, not zeros.
Grade	Classification	Yield	Tensile	Elong.	Impact (lowest published)
OK Autrod 309L POFIS recommends	ER309L (AWS A5.9)	440 MPa	600 MPa	32 %	90 J at −110 °C
OK Autrod 309MoL	ER309LMo (mod) (AWS A5.9)	400 MPa	600 MPa	31 %	65 J at −60 °C
OK Autrod 309LSi	ER309LSi (AWS A5.9)	440 MPa	600 MPa	35 %	110 J at −50 °C
OK Tigrod 309MoL	ER309LMo (mod) (AWS A5.9)	510 MPa	630 MPa	26 %	130 J at 20 °C
OK Tigrod 309L	ER309L (AWS A5.9)	430 MPa	590 MPa	32 %	90 J at −110 °C
Exaton 24.13.LHF (GMAW)	ER309L (AWS A5.9)	450 MPa	610 MPa	30 %	35 J at −196 °C

OK Autrod 309L ER309L (AWS A5.9)

The standard over-alloyed MIG wire for stainless to carbon steel, 0.8 mm to 1.2 mm, with the best toughness of the plain grades at 160 J at room temperature and 90 J at −110 °C.

Diameters: 0.8 mm, 0.9 mm, 1.0 mm, 1.2 mm
Alloy type: Austenitic, approx. 9 % ferrite — 24 % Cr, 13 % Ni, low C
Type: Solid MIG wire (GMAW), shielding M12 / M13
Source: ESAB Filler Metal Handbook, page 4-60

OK Autrod 309MoL ER309LMo (mod) (AWS A5.9)

The molybdenum-bearing wire for joints whose stainless side is 316 or 316L, at roughly 22 % Cr, 15 % Ni and 3 % Mo. The widest diameter range here at 0.8 mm to 1.6 mm. Classified as a modified composition — check against the WPS.

Diameters: 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm
Alloy type: Austenitic, approx. 8 % ferrite — 22 % Cr, 15 % Ni, 3 % Mo, low C
Type: Solid MIG wire (GMAW)
Source: ESAB Filler Metal Handbook, page 4-62

OK Autrod 309LSi ER309LSi (AWS A5.9)

High silicon for wetting and a flatter bead, which on cladding and surfacing directly reduces the passes needed to cover an area. 0.8 mm to 1.2 mm.

Diameters: 0.8 mm, 0.9 mm, 1.0 mm, 1.2 mm
Alloy type: Austenitic, approx. 8 % ferrite — 24 % Cr, 13 % Ni, low C
Type: Solid MIG wire (GMAW), shielding M12 / M13
Source: ESAB Filler Metal Handbook, page 4-61

OK Tigrod 309MoL ER309LMo (mod) (AWS A5.9)

The strongest grade on this page at 510 MPa yield, carrying molybdenum for joints to 316 and 316L. Classified as a modified composition rather than the plain class.

Alloy type: Austenitic, approx. 8 % ferrite — 22 % Cr, 15 % Ni, 3 % Mo, low C
Type: TIG rod (GTAW)
Source: ESAB Filler Metal Handbook, page 4-89

OK Tigrod 309L ER309L (AWS A5.9)

The plain TIG rod with approximately 10 % ferrite, holding 160 J at room temperature and 90 J at −110 °C under pure argon. TIG dilutes less than MIG, which is an argument for using it on the root pass of a dissimilar joint.

Alloy type: Austenitic, approx. 10 % ferrite — 24 % Cr, 13 % Ni, low C
Type: TIG rod (GTAW), shielding I1
Source: ESAB Filler Metal Handbook, page 4-87

Exaton 24.13.LHF (GMAW) ER309L (AWS A5.9)

The deliberately high-ferrite grade at approximately 14 %, for additional hot cracking resistance on heavily diluted or restrained joints. The trade is low-temperature toughness: 35 J at −196 °C.

Diameters: 1.2 mm
Alloy type: Austenitic, approx. 14 % ferrite — 24 % Cr, 13 % Ni, low C
Type: Solid MIG wire (GMAW), shielding M12 / M13
Source: ESAB Filler Metal Handbook, page 4-115

Diameters are listed from the manufacturer's deposition data. Ordering part numbers and pack sizes are confirmed with your quotation — send the grade and diameters you need to weldiv@pofis.ae.

Specifying

Which ER309L / ER309LSi / ER309LMo grade to specify

For general dissimilar joints by MIG

OK Autrod 309L is the standard wire, 0.8 mm to 1.2 mm under M12 or M13, giving 440 MPa yield, 600 MPa tensile, 160 J at room temperature and 90 J at −110 °C. For most stainless-to-carbon-steel work on a wire feeder this is the grade to quote.

For cladding and surfacing

OK Autrod 309LSi adds silicon for better wetting and a flatter bead, which on overlay work directly reduces the number of passes needed to cover an area. Same 0.8 mm to 1.2 mm range, 440 MPa yield and 600 MPa tensile with 120 J at room temperature.

When the stainless side is 316 or 316L

OK Autrod 309MoL carries roughly 3 % molybdenum at 22 % Cr and 15 % Ni, in 0.8 mm to 1.6 mm — the widest range here. OK Tigrod 309MoL is the TIG equivalent and the strongest grade on this page at 510 MPa yield. Note both are classified ER309LMo (mod), a modified composition rather than the plain class; check that against your WPS.

For TIG roots on dissimilar joints

OK Tigrod 309L gives 430 MPa yield, 590 MPa tensile, 160 J at room temperature and 90 J at −110 °C under pure argon. For a dissimilar root that has to be sound first time, the lower dilution of TIG with filler compared with MIG is itself an argument for using it on the root pass.

Where high ferrite is wanted

Exaton 24.13.LHF is the high-ferrite grade at approximately 14 %, giving 450 MPa yield and 610 MPa tensile with 110 J at room temperature. Higher ferrite buys additional hot cracking resistance on heavily diluted or restrained joints, at some cost in low-temperature toughness — it gives 35 J at −196 °C against 90 J at −110 °C for the standard grade.

Storage & handling

Storing and handling ER309L / ER309LSi / ER309LMo consumables

Keep the arc off the carbon steel

Every technique that lowers dilution helps on these joints and most cost nothing: lower current, stringer beads rather than weaving, smaller wire diameters, the highest travel speed the position allows, and intermediate cooling. The single most effective habit is not striking or holding the arc on the ferritic parent — work off weld metal already deposited.

Verify ferrite on clad surfaces

Where 309L is used for cladding rather than a one-off joint, the ferrite in the finished surface is normally specified and measured by ferrite meter or metallographic count. Agree the method and acceptance range with the client before welding, not after.

Frequently asked

ER309L / ER309LSi / ER309LMo — common questions

What wire is used to weld stainless steel to carbon steel?

ER309L, or ER309LMo when the stainless side is 316 or 316L. The molten pool takes metal from both sides — ESAB puts MIG dilution at 25 to 40 % — and a matching 308L or 316L deposit diluted that heavily can solidify partly martensitic and crack. ER309L is deliberately over-alloyed at roughly 24 % chromium and 13 % nickel so it stays austenitic after dilution.

What is the difference between ER309L and ER309LMo?

Molybdenum, at roughly 3 %. Use ER309LMo when the stainless side of the joint is 316 or 316L, so the pitting resistance that grade was chosen for carries through the weld. Note that ESAB classifies its 309MoL grades as ER309LMo (mod) — a modified composition — which is worth checking against a WPS that names the plain class.

What is the difference between ER309L and ER309LSi?

Silicon content. Silicon lowers the pool surface tension so the bead wets out flatter, which on cladding and surfacing work directly reduces the number of passes needed to cover an area. The alloy is otherwise the same, and both carry the same over-alloying for dissimilar joints.

How much does each welding process dilute a dissimilar joint?

ESAB gives electroslag strip 5–15 %, submerged arc strip 15–25 %, stick welding 15–30 %, TIG with filler 20–40 %, MIG/MAG 25–40 %, submerged arc wire 40–50 %, and TIG without filler 100 %. The ranges come from parameter choice rather than process variability, so dilution is reduced by lower current, stringer beads, smaller diameters and higher travel speed.

What is the maximum service temperature for a 309L dissimilar joint?

300 °C. ESAB states that austenitic consumables in a heterogeneous joint should see no post-weld heat treatment and a maximum service temperature of 300 °C, because above that chromium carbides precipitate at the grain boundaries and deplete the grains of chromium. The limit applies to the wire exactly as to the electrode. Above 300 °C, use a nickel-based filler such as Alloy 82.

Why does ER309L have more ferrite than ER308L?

Because it is over-alloyed. A richer chromium and nickel balance produces more delta ferrite in the deposit — ESAB publishes approximately 8 to 10 % for the standard 309L grades and approximately 14 % for the high-ferrite Exaton 24.13.LHF. Higher ferrite buys hot cracking resistance at some cost in low-temperature toughness, which is why the high-ferrite grade gives 35 J at −196 °C where the standard grade gives 90 J at −110 °C.

Can ER309L be used for ordinary stainless welding?

It can, but it should not be. On a 304L-to-304L or 316L-to-316L joint it deposits an unnecessarily over-alloyed, higher-ferrite weld that costs more and gives nothing back — and on 316L it would have no molybdenum at all unless the Mo grade were used. Match the parent with ER308L or ER316L, and keep 309L for joints that genuinely dilute.

Who supplies ER309L wire in Abu Dhabi?

POFIS supplies the full ESAB OK Autrod, OK Tigrod and Exaton stainless ranges from Abu Dhabi across the UAE and the wider GCC, as an ESAB Authorized Distributor and Service Centre, approved ADNOC vendor and ISO 9001 certified supplier. Send both parent grades, the service temperature and any ferrite acceptance range and we will confirm the grade before quoting. Email weldiv@pofis.ae.

Procurement & supply

Buying the ER309L / ER309LSi / ER309LMo consumables through POFIS

The ER309L / ER309LSi / ER309LMo consumables is supplied from Abu Dhabi by Perfect Oilfield & Industrial Supply LLC as an ESAB Authorized Distributor and Service Centre. The information below covers what procurement and QA/QC departments normally need before raising a purchase order.

Lead time

Stock items dispatch from Abu Dhabi within 24–48 hours. Indent items are quoted with a confirmed lead time at the time of offer.

Approved vendor status

POFIS is an approved ADNOC vendor and is listed on the approved vendor lists (AVL) of major operators and EPC contractors across the GCC. We can complete supplier registration and prequalification documentation on request.

Payment terms

Standard credit terms are available to registered corporate accounts. LPO, LC and advance payment are all accepted.

Delivery terms

Delivery across the UAE and the wider GCC. Quotations can be issued on EXW, FOB, CIF or DDP terms to suit your project.

Warranty

Full manufacturer warranty, honoured locally. As an ESAB Authorized Service Centre we carry out warranty work and repairs in Abu Dhabi rather than returning equipment abroad.

Service & spares

In-UAE service, commissioning, operator training and spare parts backing for every machine we supply.

ISO 9001 Certified
Approved ADNOC Vendor
ESAB Authorized Distributor & Service Centre

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