Material guide
Welding Stainless Steel: Australian Practice Guide
Stainless rewards control: the right gas, matched filler, fast travel, and tools that never touch carbon steel. Done right it stays chrome-bright for decades in coastal air.
Process and filler selection
Default process: TIG for quality, MIG with tri-mix or 98/2 argon-CO2 for speed. Filler: ER308L (304 grade), ER316L (316 grade) — match the parent metal.
Preparation
Dedicated stainless brushes and discs — carbon steel contamination causes rust later. Fit-up matters more than settings: gaps eat filler and heat control at exactly the wrong moment.
Heat management
Low thermal conductivity but retains heat: lower amps (~10% under mild steel), faster travel, or it sugars and distorts
Gas and settings
TIG on pure argon is the quality default. MIG stainless wants 98/2 argon-CO2 (or a tri-mix) — a steel mix corrodes the weld over time. Run about 10% less current than mild steel: stainless holds heat and sugars (blackberry oxidation) when cooked. Back-purge the root with argon or use backing flux paste on anything that must stay clean both sides.
The contamination rule
- Dedicated stainless-only brushes and grinding discs — iron contamination rusts the weld later
- Match filler to grade: ER308L for 304, ER316L for 316 (marine/coastal default in Australia)
- Faster travel than steel: slower = more heat = sugaring and warpage
- Deburr and passivate/pickle the finished weld to restore corrosion resistance
Frequently asked questions
Can you weld aluminium with a MIG welder?
Yes, with two conditions: the machine supports a spool gun or has an aluminium-capable drive, and you use 100% argon with aluminium wire (ER4043 or ER5356). Soft aluminium wire jams in long conventional MIG torch liners — that's what the spool gun solves. Thickness under ~1.6 mm belongs on TIG.
How to weld mild steel
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).
What filler wire or rod for mild steel?
For mild steel use ER70S-6 MIG wire, E48xx stick rods, ER70S-2 TIG rod. Matching filler to the parent grade is the rule — mismatched filler either cracks, corrodes or underperforms the base metal.
Best welding process for mild steel?
The best process for mild steel is MIG or stick, gasless flux-core outdoors — chosen for how the metal conducts heat and what contamination costs you.
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