Unknown Stainless vs Dissimilar Metal Stainless Rod
E312-16 crack-resistant unknown stainless rod vs E309L-16 standard dissimilar metal rod. Both handle mixed metals but differently.
Key Differences
| Attribute | E312-16 | E309L-16 |
|---|---|---|
| Primary Use | Unknown stainless, crack repair | Stainless to carbon steel joints |
| Ferrite Content | High (25-50 FN) - crack resistant | Moderate (8-20 FN) |
| Chemistry | 29Cr-9Ni duplex | 23Cr-13Ni austenitic |
| Cracking Resistance | Highest of any stainless rod | Good |
| Corrosion Resistance | Mixed - not true austenitic | Good - matches 300 series |
| Temperature Limit | 700F max (sigma phase risk) | 800F |
| Availability | Less common | Very common |
| Cost | Higher | Standard stainless pricing |
Use E312-16 when:
Use E309L-16 when:
How E312-16 and E309L-16 Work Together
E309L-16 is the standard choice when you know one side is stainless and the other is carbon steel. E312-16 is the rescue rod when you do not know what stainless grade you are welding, or when E309L-16 cracked. The high ferrite content of E312-16 gives maximum crack resistance. For routine stainless-to-carbon steel production joints, use E309L-16. For repair work on unknown castings or when previous welds cracked, try E312-16.
Common Mistake With Unknown Stainless
Reaching for E312-16 as a first choice for stainless-to-carbon joints. It works, but E309L-16 is better matched for the dilution chemistry of a known dissimilar joint. Save E312-16 for when you need its crack resistance as a problem solver.
Where to Buy
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