ER309L
Best for: Common dissimilar filler for stainless steel to carbon steel joints.
Helps manage dilution between stainless and mild steel. Check joint design, service conditions and WPS.
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Welding Filler Metal Selector
Choose a region, parent materials and welding process to get a practical filler wire, TIG rod or MMA electrode suggestion for common fabrication and site welding work. Use it for quick guidance around MIG, TIG, MMA, mild steel, stainless steel, aluminium and dissimilar welding, then check the WPS and job specification before welding.
CoversMIG / MAG, TIG and MMA / Stick
RegionsUK, USA and Europe wording
ReminderAlways check the WPS and data sheet
Use the selector
Choose a common filler metal starting point
Select the region, material pair and welding process. The result updates with a suggested filler metal, process form, classification wording, common-use reason and a check-before-welding reminder for common mild steel, stainless steel and aluminium starting points. The material guide below the result also explains the common use of the parent metals being welded, so the selector supports both filler choice and practical material understanding.
Free selector
Welding Filler Metal Selector
Auto-updatesSuggestion updates automatically as you change the material, process and region.
Suggested starting point
309L / 309LSi dissimilar stainless MIG wire
Also known as ER309L / ER309LSi
Main suggestionER309L or ER309LSi stainless MIG wire
Also known asER309L / ER309LSi
Process formMIG / MAG wire
UK classificationER309L / ER309LSi stainless MIG wire as common dissimilar stainless-to-carbon starting points. Confirm the EN ISO classification on the consumable data sheet.
What is the difference?
ER309LSi
Best for: MIG/MAG stainless-to-carbon steel work where wetting, bead profile and flow are useful.
Similar to ER309L but with added silicon, often improving MIG/MAG running and bead appearance.
Why this is commonly used
309 type filler is commonly used for stainless to carbon steel dissimilar joints because it helps tolerate dilution.
Check before welding
This is general guidance only. Always confirm the parent material grade, WPS, job specification, service environment and consumable data sheet before welding.
Material guide
About the materials being welded
This support section updates with your material selections so you can quickly see what the parent metals are commonly called, where they are used and what to watch before welding.
Stainless steel 304
- Common names
- 304 stainless, 304L, 18/8 stainless
- Usually used for
- General stainless fabrication, kitchens, food areas, decorative work, light external use, handrails and clean indoor environments.
- Why it is chosen
- Good general corrosion resistance, clean appearance and strong availability.
- Welding note
- Usually welded with 308L / 308LSi filler for matching 304 or 304L stainless.
- Watch out
- Not ideal for marine, salt, high-chloride or aggressive wet environments. 316 is normally preferred where better chloride resistance is needed.
Mild steel
- Common names
- Mild steel, carbon steel, black steel, S275, S355
- Usually used for
- General fabrication, frames, brackets, gates, supports, structural steelwork and workshop repairs.
- Why it is chosen
- Low cost, widely available, easy to cut, drill, weld and fabricate.
- Welding note
- Commonly welded with A18 / ER70S-6 type MIG wire for general mild steel work, depending on the job and specification.
- Watch out
- Mild steel rusts if left unprotected. Outdoor work normally needs painting, powder coating, galvanising or another corrosion protection system.
General material guidance only. Always confirm the exact grade, service environment, WPS, job specification and consumable data sheet before welding.
Need RAMS for welding work?
Connect filler choice back to the job controls.
Fabora RAMS helps fabrication, welding and steel installation businesses create editable welding method statements and risk assessments faster.
Practical use
Use the result as guidance, not a final welding instruction
Filler metal selection can depend on parent material certificates, service temperature, corrosion exposure, dilution, joint design, heat input, client specification and the approved welding procedure.
Same-material stainless joints
The selector covers common 304/304L, 316/316L, 321 and 310 stainless starting points while keeping low-carbon and stabilised-filler checks visible.
Stainless to mild steel
For common 304/316 stainless to carbon steel joints, the tool points toward 309 type dissimilar filler choices and asks you to check dilution and service conditions.
Galvanised steel warning
Galvanised steel selections keep a fume warning visible because zinc oxide exposure controls, coating removal, LEV, RPE and risk assessment matter before work starts.
Aluminium alloy checks
Aluminium results keep preparation, shielding gas, alloy, temper, colour match, corrosion exposure, strength and service-condition checks visible before the filler is treated as suitable for the job.
Reference context
These external sources are useful context only. The selector still does not replace a WPS, welding engineer or consumable supplier data sheet.
Related Fabora links
Connect filler selection to RAMS, risk assessment and method planning
Use the selector for a quick consumable starting point, then link the welding task back to the risk assessment, method statement, COSHH review and site RAMS.
FAQs
Welding filler metal selector FAQs
What is A18 welding wire?
A18 is a common UK workshop or supplier term used for general mild steel MIG wire. Depending on the supplier and data sheet, you may also see related classifications or names such as ER70S-6, SG2 or G3Si1. Always confirm the exact consumable classification on the data sheet and against the WPS or job specification.
What filler wire should I use for 304 stainless?
304 and 304L stainless are commonly welded using 308L or 308LSi filler metal for many MIG, MAG and TIG jobs. You still need to check the WPS, job specification, parent material certificate, service environment and consumable data sheet before welding.
What is the difference between 308L and 308LSi welding wire?
308L is a common low-carbon stainless filler for 304/304L stainless. 308LSi is similar but includes added silicon, which can improve wetting, flow and bead appearance in MIG/MAG welding. The final choice should follow the WPS, material grade, service conditions and consumable data sheet.
What filler should I use for stainless steel to mild steel?
309L or 309LSi is a common dissimilar filler choice for stainless steel to mild steel because it helps tolerate dilution. The final choice still depends on the specification, service conditions, parent materials, procedure and consumable data sheet.
What is the difference between 309L and 309LSi welding wire?
309L is a common dissimilar stainless filler for stainless steel to mild steel joints. 309LSi is a silicon-enhanced version often used in MIG/MAG welding where better wetting and bead appearance are useful. The job specification and data sheet should confirm the final choice.
What filler wire should I use for 6061 aluminium?
6061 aluminium is commonly welded with 4043 or 5356 filler, but the better choice depends on the job specification, strength requirements, anodising or colour match, service conditions and consumable data sheet. Heat-treated 6061 can lose strength in the heat affected zone after welding, so the WPS and design requirements must be checked.
What is the difference between 4043 and 5356 aluminium filler?
4043 is an aluminium-silicon filler often chosen for good fluidity, weldability and reduced cracking risk on many 6xxx and cast aluminium jobs. 5356 is a magnesium-bearing aluminium filler often considered where strength, ductility or anodising colour match matter. The final choice must follow the WPS, parent alloy and service conditions.
What is the difference between MIG wire, TIG rod and MMA electrode?
MIG or MAG usually uses a continuous wire fed through the torch. TIG uses a separate filler rod added by hand. MMA or stick welding uses a flux-coated electrode that melts into the weld while the flux helps shield the weld pool.
Are filler metal names different in the UK, USA and Europe?
The trade wording can look similar, but the standards and classifications are often shown differently. USA data sheets commonly emphasise AWS classifications, while UK and European data sheets may show EN ISO classifications alongside trade names such as 308L, 309L, SG2 or G3Si1.
Can this tool replace a WPS?
No. This selector is general guidance only. It does not replace a WPS, qualified procedure, welding engineer, client specification, material certificate, service review or consumable manufacturer data.