Dissimilar Metal vs Standard Stainless Wire
ER309L for stainless-to-carbon steel vs ER308L for stainless-to-stainless. Different dilution chemistry for different joint types.
Which One Should You Use?
Pick ER309L if:
Runs on DCEP, DCEN, 40-200A range. ER309L full amperage chart
Pick ER308L if:
Runs on DCEP, DCEN, 40-300A range. ER308L full amperage chart
Key Differences
| Attribute | ER309L | ER308L |
|---|---|---|
| Primary Use | Stainless to carbon steel joints | Stainless to stainless joints |
| Chromium | ~23% (higher for dilution) | ~20% |
| Nickel | ~13% (higher for dilution) | ~10% |
| Dilution Tolerance | Designed for mixed-metal dilution | Not designed for carbon steel dilution |
| Cost | Higher (more alloy) | Lower |
| Also Used For | First pass of stainless cladding | All-pass 304/304L welding |
| Crack Risk on Dissimilar | Low | High (martensite formation) |
Settings at a Glance
Machine settings and operating characteristics side by side. For full amperage charts, see the individual electrode pages.
| Setting | ER309L | ER308L |
|---|---|---|
| Polarity | DCEP, DCEN | DCEP, DCEN |
| Positions | flat, horizontal, vertical-up, overhead | flat, horizontal, vertical-up, overhead |
| Penetration | medium | medium |
| Coating | bare wire | solid wire |
| Amps at 0.030" | 40-150A | N/A |
| Amps at 0.035" | 60-200A | N/A |
| Amps at .030" | N/A | 40-140A |
| Amps at .035" | N/A | 60-200A |
How ER309L and ER308L Work Together
When both sides of the joint are 304 stainless, use ER308L. When one side is stainless and the other is carbon steel, use ER309L. The higher alloy content of ER309L compensates for carbon steel dilution so the weld deposit maintains austenitic stainless properties. If you use ER308L on a dissimilar joint, the diluted weld may form martensite and crack. All stainless steel welding generates hexavalent chromium fumes, a known carcinogen. Use local exhaust ventilation or a supplied-air respirator per OSHA requirements.
Common Mistake With Dissimilar Metal
Using ER308L to join stainless to carbon steel because it was already loaded in the MIG. The carbon steel dilution drops the chromium and nickel below the threshold needed for an austenitic deposit, leading to a martensitic or mixed microstructure that is brittle and crack-prone.
Practical Differences
| Factor | ER309L | ER308L |
|---|---|---|
| Common Brands | Blue Max 309L, Hobart 309L | Blue Max 308L, Hobart 308L |
Where to Buy
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ER309L vs ER308L: Common Questions
Which is better, ER309L or ER308L?
Wrong question. They solve different problems. Key differences: Primary Use: ER309L has stainless to carbon steel joints, while ER308L has stainless to stainless joints. Chromium: ER309L has ~23% (higher for dilution), while ER308L has ~20%. Nickel: ER309L has ~13% (higher for dilution), while ER308L has ~10%. The comparison table on this page breaks down each trade-off.
Can I substitute ER309L for ER308L?
Only if the specs allow it. Coating chemistry is different (bare wire vs solid wire), so the arc and slag behave differently.
Can I use both ER309L and ER308L on the same joint?
When both sides of the joint are 304 stainless, use ER308L. When one side is stainless and the other is carbon steel, use ER309L. The higher alloy content of ER309L compensates for carbon steel dilution so the weld deposit maintains austenitic stainless properties. If you use ER308L on a dissimilar joint, the diluted weld may form martensite and crack. All stainless steel welding generates hexavalent chromium fumes, a known carcinogen. Use local exhaust ventilation or a supplied-air respirator per OSHA requirements.
Reference data only. Verify all settings against manufacturer documentation and the applicable welding code before use. Amperage ranges are starting points that vary by position, fit-up, and material. Welding involves serious injury risks including burns, electric shock, fume exposure, and fire. This site does not replace proper training, certification, or employer safety procedures. See full terms of use.
Data sourced from AWS A5.9/A5.9M.