Materials
What filler wire or rod for 4130 chromoly?
Quick answer
For 4130 chromoly use ER80S-D2, or ER70S-2 for less critical tube work. Matching filler to the parent grade is the rule — mismatched filler either cracks, corrodes or underperforms the base metal.
Filler selection
- Process choice: TIG with ER80S-D2 filler
- Filler: ER80S-D2, or ER70S-2 for less critical tube work
- Prep: acetone wipe, clean tungsten, tight fit-up
Why matching matters
Filler chemistry controls strength, corrosion behaviour and crack resistance. The classic Australian mistake is welding 316 stainless with 308 filler — it works, until the job sits in a coastal or chemical environment and the weld rusts first. When in doubt, weld with a filler at least as alloyed as the parent.