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.
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) |
Use ER309L when:
Use ER308L when:
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.
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.
Where to Buy
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Data sourced from .