5 Different TIG Welding Filler Rod Types Explained

When it comes to welding, a MIG welder is very forgiving. It has a spool of wire inside and all you have to do is pull the trigger and it lays down a pretty nice weld. But if you’re welding different types of metal, or you need a nicer weld, the TIG welder comes into play. And for that, you need filler rod.

ER70S-6 Filler Rod ~ Mild Steel

The ER70S-6 rod is for mild steel. It’s the most common type of filler rod found in an automotive shop and is great for sheet metal, chassis, and suspension components. The -6 at the end means it has more oxidizers in it which helps provide a flatter and quicker bead. It’s an alloy which means it has other metals, like copper and chromium in it in small quantities. That’s what gives it its shiny copper color.

308L Filler Rod ~ Stainless Steel

Next up is 308L. This is for welding stainless steel to stainless steel. The most common types of stainless steel in an automotive shop are 304 and 409. It’s an alloy of mostly iron with about 10% nickel and around 20% chromium.

309L Filler Rod ~ Mild Steel to Stainless Steel

If you’re going to weld stainless steel to mild steel, you’re going to need 309L as it’s ideal for wearing non-similar steel. It’s made up of 13% nickel and 24% chromium along with other additives. You can also use 309 for welding similar alloys like 304 stainless to 409 stainless.

Aluminum Filler Rod

Aluminum filler rod is only good for welding aluminum to aluminum.

Silicon Bronze Filler Rod

Silicon bronze filler rod will do just about anything. You can weld steel, bronze, brass, or any combination. Just remember, it won’t be as strong as a regular steel weld.