Slide 003: TIG Welding Parameters & Material-Specific Techniques¶
Slide Visual¶
Slide Overview¶
This slide covers parameter selection for TIG welding across three common materials and the material-specific techniques needed for quality results on each.
Instruction Notes¶
TIG Parameter Reference β Starting Values¶
Mild Steel (DCEN, 100% Argon)
| Thickness | Tungsten | Filler Rod | Amps | Cup Size | Gas (CFH) |
|---|---|---|---|---|---|
| 20 ga (0.036") | 1/16" | 1/16" ER70S-2 | 30-50 | #5-6 | 15-18 |
| 16 ga (0.060") | 3/32" | 1/16" ER70S-2 | 50-80 | #6-7 | 15-20 |
| β " (0.125") | 3/32" | 3/32" ER70S-2 | 80-120 | #7-8 | 18-22 |
| 3/16" | 3/32"-β " | 3/32" ER70S-2 | 120-170 | #8 | 20-25 |
| ΒΌ" | β " | β " ER70S-2 | 160-220 | #8-10 | 20-25 |
Stainless Steel (DCEN, 100% Argon)
| Thickness | Tungsten | Filler Rod | Amps | Notes |
|---|---|---|---|---|
| 18-16 ga | 1/16"-3/32" | 1/16" ER308L | 40-70 | Keep heat LOW β stainless retains heat |
| β " | 3/32" | 3/32" ER308L | 70-110 | Back purge recommended |
| 3/16" | 3/32" | 3/32" ER308L | 100-150 | Back purge required for corrosion resistance |
Aluminum (AC, 100% Argon)
| Thickness | Tungsten | Filler Rod | Amps | AC Balance | AC Frequency |
|---|---|---|---|---|---|
| 16 ga (0.060") | 3/32" Pure/Lanthanum | 3/32" ER4043 | 60-100 | 65-70% EN | 100-120 Hz |
| β " | 3/32"-β " | 3/32" ER4043 | 100-150 | 65-70% EN | 80-120 Hz |
| 3/16" | β " | β " ER4043 | 140-200 | 60-70% EN | 60-100 Hz |
| ΒΌ" | β " | β " ER4043 | 180-250 | 60-65% EN | 60-80 Hz |
Stainless Steel Technique¶
Stainless steel has low thermal conductivity β heat stays concentrated near the weld: - Use 10-15% LESS amperage than mild steel of the same thickness - Travel faster than on steel β minimize heat input to reduce HAZ and distortion - Back purging: Flow argon on the backside of the joint to prevent oxidation. Use a purge dam (aluminum tape or foam) to contain the gas. Critical for pipe and any application requiring corrosion resistance - Heat tint colors: Straw/light gold = acceptable. Dark blue/purple/gray = excessive oxidation, needs removal
Aluminum Technique¶
Aluminum requires fundamentally different technique: - AC settings: AC balance controls the ratio of cleaning (EP) to penetration (EN). 65-70% EN is a good starting point. AC frequency affects arc focus: higher Hz = narrower, more focused arc - The oxide layer: AlβOβ melts at 3,700Β°F while aluminum melts at 1,220Β°F. The AC cleaning action breaks the oxide, but you must still wire brush the surface clean before welding - Pool behavior: Aluminum goes from solid to liquid with almost no visible warning (no color change like steel). Watch for a bright, mirror-like pool to form - Heat sinking: Aluminum conducts heat rapidly. The first inch of weld needs more amps than the middle (material is cold). As the part heats up, reduce amps to prevent burn-through - Filler rod: Feed larger amounts of filler than steel β aluminum contracts significantly during cooling, and insufficient filler causes cracking
Common Rule: Post-Flow¶
For all TIG welding: post-flow = 1 second per 10 amps of final welding current. At 100A, maintain gas flow for 10 seconds after the arc stops. This protects the hot tungsten and weld crater from oxidation.
Key Talking Points¶
- Each material requires different polarity, parameters, and technique
- Stainless steel: minimize heat input, back purge for corrosion resistance
- Aluminum: AC polarity, watch for the pool carefully β it appears suddenly
- Post-flow duration matters β 1 second per 10 amps is the rule
- These are starting values β always run test beads before welding production parts
Learning Objectives (Concept Check)¶
- [ ] Select correct TIG parameters for steel, stainless, and aluminum
- [ ] Explain why AC is required for aluminum and what AC balance controls
- [ ] Describe the back purging technique for stainless steel
Last Updated: 2026-03-19