Which Welding Rod for Stainless to Carbon Steel Joints
Joining stainless to carbon steel is one of the most common dissimilar metal welding jobs. It shows up at flanges, transitions, brackets welded to stainless tanks, and anywhere stainless equipment connects to carbon steel structure. The filler must compensate for dilution from the carbon steel side to maintain corrosion resistance.
Recommended Electrodes
E309L-16
The standard stick electrode for stainless-to-carbon joints. 23Cr-13Ni chemistry compensates for carbon steel dilution. Runs on AC or DCEP. Use when stick welding is the available process.
ER309L
Wire version for MIG or TIG. Same chemistry as E309L-16 in wire form. Use 98/2 Ar/CO2 for MIG, 100% argon for TIG. Preferred for pipe and tubing applications.
E312-16
Use when the standard E309L-16 cracks. E312-16 has the highest crack resistance of any common stainless rod. Also suitable when the stainless grade is unknown.
Technique Tips
Direct the arc toward the stainless side of the joint. Stainless has lower thermal conductivity, so it heats up faster. Pointing the arc at the carbon steel helps equalize the heat distribution. Keep interpass temperature below 350F to prevent sensitization. On pipe, back purge the stainless side with argon to prevent oxidation.
For structural connections, the weld metal from E309L remains austenitic and corrosion-resistant despite dilution. But the heat-affected zone on the carbon steel side will not be corrosion-resistant. If the carbon steel side needs protection, it must be painted or coated.
Common Mistakes to Avoid
Using E308L-16 or ER308L on stainless-to-carbon joints. The dilution from carbon steel reduces chromium content below the threshold for corrosion resistance. The weld looks fine but corrodes rapidly in service. Using 75/25 Ar/CO2 gas on MIG wire, which causes carbon pickup and sensitization.
Related Comparisons
Similar Guides
As an Amazon Associate, GageRef earns from qualifying purchases. Supplier links on this site are affiliate links.