Materials
How to weld mild steel
Quick answer
To weld mild steel: use MIG or stick, gasless flux-core outdoors, filler matched to the parent metal (ER70S-6 MIG wire, E48xx stick rods, ER70S-2 TIG rod), and prepare properly — grind back to bright metal at least 20 mm each side of the joint. The key adjustment vs mild steel: baseline (40 A/mm MIG rule).
Process and filler
Process: MIG or stick, gasless flux-core outdoors. Filler: er70s-6 MIG wire, E48xx stick rods, ER70S-2 TIG rod. The default Australian fabrication material — forgiving, cheap, every process works
Preparation
Grind back to bright metal at least 20 mm each side of the joint. Fit-up matters more than most beginners expect: a gap you can see daylight through is a gap the filler has to fill, at the cost of heat control.
Amps and approach
Set current by thickness as you would for steel, then apply the adjustment: baseline (40 A/mm MIG rule). Run test coupons first — every mild steel joint tells you loudly when the parameters are wrong.