FAQ: TIG Welding Techniques & Amperage
What's the hardest thing to weld with TIG techniques?
Aluminum, titanium, and thin-gauge metals under 0.5mm are the most challenging materials for TIG welding techniques due to their thermal conductivity and oxidation risks. Aluminum's 1220°F melting point versus steel's 2500°F (ASM International) requires precise heat control to avoid burn-through.
Why is aluminum problematic for TIG?
Aluminum reflects heat unpredictably, needing AC current and 2x the amperage of steel. The oxide layer melts at 3700°F - three times higher than the base metal.
How does titanium differ from stainless steel?
Titanium reacts with oxygen above 800°F, requiring back purging and trailing shields. Its thermal conductivity is 1/6th of stainless steel, causing rapid heat buildup.
What amperage do I need for a professional TIG welder?
Professional TIG welding techniques require 1 amp per 0.001" material thickness (Lincoln Electric guide), with machines offering 5-300A ranges. For 1/8" steel, set 125A; for 1/8" aluminum, use 150-175A due to higher conductivity.
How does amperage change for aluminum vs. steel?
Aluminum needs 30-50% more amps than steel at equal thickness. A 3/16" steel joint uses 190A, while aluminum requires 250A with AC balance at 70% cleaning action.
Why does duty cycle matter at high amps?
At 200A, air-cooled torches last only 10 minutes before overheating (60% duty cycle), while water-cooled systems maintain continuous operation (Weldcraft spec).
What is the difference between HF start and lift arc TIG?
HF start initiates the arc without contact in <0.1 sec (Miller Electric spec), while lift arc requires tungsten-to-workpiece contact and takes 0.3 sec. HF works better for thin metals; lift arc prevents electromagnetic interference in sensitive environments.
When should I avoid HF start?
Near computers or medical devices - HF generates RF noise up to 5MHz that disrupts electronics (VERIFY: IEEE C95.1 standard).
Does lift arc damage tungsten?
Yes - each contact contaminates the electrode with base metal, requiring 15-20% more frequent grinding than HF starts.
How do I prevent tungsten contamination when TIG welding?
Use 2% ceriated tungsten (lasts 3x longer than pure tungsten per ESAB tests) and grind electrodes longitudinally - cross-grinding introduces micro-cracks. Maintain 1/8" stick-out and 15-20° work angle to minimize accidental contact.
What color indicates tungsten poisoning?
Blue/green discoloration means copper contamination from brazed joints; black spots signal carbon pickup from hydrocarbon vapors.
Why does my TIG weld look discolored or porous?
Discoloration signals oxygen contamination - increase argon flow to 15-20 CFH (American Welding Society standard) and extend post-flow to 1 second per 10 amps. Porosity occurs when gas coverage drops below 12 CFH or with drafts over 2 mph.
How do I test gas coverage?
Light a match near the weld zone - if the flame extinguishes, shielding is adequate. For critical welds, use a gas lens cup.
Which TIG welding techniques require water cooling?
Water cooling becomes essential above 200A or for duty cycles exceeding 60% (Weldcraft torch specifications). Industrial aluminum welding at 250A+ demands closed-loop chillers maintaining coolant below 120°F.
What happens without cooling?
Torch heads overheat at 300°F+, melting insulators and reducing cable lifespan by 80% (VERIFY: TBi Industries test data).
What's the bottom line on mastering TIG welding techniques?
Precision control separates professional TIG welding from amateur results. Three non-negotiable rules:
• Amperage rules: 1A per 0.001" material thickness (double for aluminum)
• Material prep: Acetone cleaning prevents 90% of contamination defects
• Ignition choice: HF for thin metals under 1/16", lift arc for EMI-sensitive areas
Frequently Asked Questions
Can you TIG weld without gas?
No - TIG welding techniques require 100% argon shielding. Even brief exposure to air causes porosity and tungsten contamination.
Why does my tungsten keep balling up?
AC welding aluminum forms a ball naturally, but DC balls indicate reversed polarity or excessive amperage (over 1.5x recommended settings).
How thin can you TIG weld?
With 0.020" tungsten and 10-15A, skilled welders join 0.005" foil - thinner than printer paper (VERIFY: Precision Welding Journal).
What's the best tungsten for stainless steel?
2% lanthanated tungsten handles 125-150A DCEN best, lasting 40% longer than thoriated types (AWS A5.12 specification).
How do I stop TIG welds from cracking?
Preheat thick sections to 300°F and use ER70S-2 filler for steel - its silicon deoxidizers prevent 80% of hot cracks (Lincoln Electric study).
Why does my arc wander on aluminum?
Dirty base metal or incorrect AC balance (set 70-80% electrode positive for cleaning action without excessive penetration).