Dissimilar Metal vs Marine Stainless Wire
ER309L for stainless-to-carbon joints vs ER316L for 316L marine applications. Different specializations that cannot substitute for each other.
Key Differences
| Attribute | ER309L | ER316L |
|---|---|---|
| Primary Use | Stainless to carbon steel | 316/316L to itself |
| Chromium | 23% | 18% |
| Nickel | 13% | 12% |
| Molybdenum | None | ~2% |
| Chloride Resistance | Moderate | Excellent (moly) |
| Dilution Tolerance | Designed for carbon steel dilution | Not designed for dilution |
| Also Used For | Cladding first layer | Food/pharma/marine fabrication |
Use ER309L when:
Use ER316L when:
How ER309L and ER316L Work Together
These wires serve completely different purposes. ER309L is designed to handle the dilution chemistry of a stainless-to-carbon steel joint. ER316L is designed to match the corrosion properties of 316/316L base metal. You would never use ER316L for a dissimilar joint (not enough alloy to handle carbon steel dilution) and you would never use ER309L on 316L base metal (lacks the molybdenum for pitting resistance).
Common Mistake With Dissimilar Metal
Using ER309L on a 316L-to-316L joint because 309L has more alloy. More alloy does not mean better. The 309L weld deposit lacks molybdenum and will corrode preferentially in chloride environments compared to the 316L base metal.
Data sourced from .