TIG Welding Stainless to Carbon...

and other uses for ER309 TIG rod 

TIG welding chromium vanadium wrenches with ER309 TIG rod

Welding stainless to carbon is common in:

• Exhaust systems
• Structural supports
• Transition joints in piping
• Pressure vessels and tanks

Welding stainless to carbon steel isn’t hard when you know the rules. The key is controlling dilution, choosing the right filler, and being careful with heat input. With the proper prep and technique, you can make strong, crack-resistant welds that stand up to the job.

Choosing the Right Filler Metal for dissimilar metals

The most important step is using a filler metal that’s compatible with both stainless and carbon steel.

Recommended Filler rods for tig welding stainless to carbon:

• ER309L – The most common filler for dissimilar welding. It has a higher alloy content that tolerates mixing with mild steel.
• ER309MoL – Same as above but with molybdenum for better corrosion resistance, often used in more aggressive environments.
• ER312 - is similar to a rod labeled "supermissile weld" and is very crack resistant

Avoid using carbon steel or standard stainless (like ER308L) fillers—they won’t handle the dilution as well and can lead to cracking.

ER309L filler rod has been used for decades to weld carbon steel to stainless steel in power plants, paper mills, refineries, and job shops.

TIG welding filler metal is in stock at Weldmonger.com