A Quick Question on TIG Welding

What's the welded base material? The most common TIG filler for mild steel is going to be ER70-S2, which is also suitable for most welding of 4130, such as on some chassis components and roll cages. You can get ER70-S6, which has more cleaning agents, for dirtier metals, but that's a crutch for TIG. Twisted up MIG wire is common for small jobs using ER70-S6. Cleanliness is next to godliness for TIG, period.

Some stainless fillers, like ER309 are useful for welding dissimilar metals, such as mild to stainless. Hobart/Miller, Lincoln and most other filler manufacturers have charts for suitable filler for each base metal. S/F....Ken M