"What TIG settings should I use for 1/8 inch steel?"

"For 1/8 inch mild steel on DCEN, use a 3/32 inch 2% lanthanated tungsten, 3/32 inch ER70S-2 filler rod, a #7 or #8 cup, 90-150 amps, and 15-25 CFH argon flow. Start at 100 amps and adjust based on puddle formation. You should see a bright, fluid puddle form within 2-3 seconds of starting the arc."

"What is the difference between DCEN and AC for TIG welding?"

"DCEN (DC Electrode Negative) concentrates 70% of heat on the workpiece, giving deep penetration. Used for steel and stainless. AC alternates between electrode negative and electrode positive, which provides cleaning action to break up aluminum's oxide layer. AC uses about 20-30% more amperage than DCEN for the same thickness because heat splits more evenly between tungsten and workpiece."

"How do I pick the right tungsten size for TIG welding?"

"Match tungsten diameter to amperage range. A 1/16 inch tungsten handles 15-80 amps. A 3/32 inch covers 60-200 amps. A 1/8 inch handles 150-350 amps. If your tungsten melts into a ball or splits, it's too small for the amperage. If you can't maintain a stable arc at low amperage, the tungsten is too large."

TIG Welding Settings Chart: Amperage, Tungsten & Filler by Thickness

TIG welding gives you the most control over heat input of any arc process, but that control requires matching tungsten size, filler rod, cup size, gas flow, and amperage to your material thickness. This chart covers the starting parameters for steel and stainless on DCEN with pure argon.

The old rule of thumb still works: 1 amp per 0.001" of material thickness. A 1/8" plate (0.125") starts around 125 amps. That gets you in the ballpark, and this chart refines it.

TIG Welding Settings: Steel & Stainless Steel (DCEN)

TIG welding settings for steel and stainless steel on DCEN with pure argon shielding gas
Material Thickness	Tungsten Diameter	Filler Rod Diameter	Cup Size	Amperage Range	Gas Flow (CFH)
0.020-0.040"	1/16"	1/16"	#4-5	15-50	10-15
0.040-0.060"	1/16"	1/16"	#5-6	40-80	12-18
0.060-0.093"	3/32"	1/16-3/32"	#6-7	60-110	15-20
0.093-0.125"	3/32"	3/32"	#7-8	90-150	15-25
0.125-0.188"	3/32-1/8"	3/32-1/8"	#7-8	120-200	18-28
0.188-0.250"	1/8"	1/8"	#8-10	175-275	20-30
0.250-0.375"	1/8-5/32"	1/8-3/16"	#8-12	225-350	25-35
0.375-0.500"	5/32"	3/16"	#10-12	300-400	28-40

TIG Settings for Aluminum (AC)

Aluminum requires AC polarity to break through the oxide layer. The electrode-positive portion of the AC cycle provides cleaning action, while electrode-negative provides penetration. Increase amperage 20-30% over the DCEN steel values for the same thickness.

TIG welding settings for aluminum on AC with pure argon shielding gas
Material Thickness	Tungsten Diameter	Filler Rod (4043/5356)	Cup Size	Amperage Range	Gas Flow (CFH)
0.040-0.063"	1/16"	1/16"	#5-6	40-70	15-20
0.063-0.093"	3/32"	3/32"	#6-7	60-100	15-22
0.093-0.125"	3/32"	3/32"	#7-8	100-160	18-25
0.125-0.188"	3/32-1/8"	3/32-1/8"	#8-10	140-210	20-28
0.188-0.250"	1/8"	1/8"	#8-10	190-300	22-32
0.250-0.375"	5/32"	1/8-3/16"	#10-12	280-400	28-38

How to Read This Chart: Example Row

Take the 0.093-0.125" row from the steel chart. This is roughly 12-gauge to 1/8" plate. The chart tells you:

Tungsten: 3/32" diameter (2% lanthanated or 2% ceriated work best)
Filler: 3/32" ER70S-2 for steel or ER308L for stainless
Cup: #7 or #8 alumina (a #7 cup has a 7/16" opening)
Amperage: Start at 100A and work up toward 150A
Gas flow: 15-25 CFH at the flowmeter

On your machine, set 120A as a starting point. Prep the tungsten to a point with about 2.5x the diameter in grind length (roughly 1/4" long taper on a 3/32" tungsten). Initiate the arc and watch the puddle. It should form within 1-2 seconds. If it takes longer, you need more amperage. If it forms immediately and starts to spread wide, back off 10A.

DC vs. AC: When to Use Each

DCEN (DC Electrode Negative) is the standard for steel and stainless steel. The electron flow goes from tungsten to workpiece, concentrating about 70% of heat on the base metal. This gives a narrow, deep penetration profile and keeps the tungsten cool.

AC (Alternating Current) is required for aluminum and magnesium. Aluminum oxide melts at 3,700 degrees F while the aluminum underneath melts at 1,200 degrees F. The EP (electrode-positive) half-cycle blasts that oxide off the surface. The EN half-cycle provides penetration. Modern inverters let you adjust AC balance (typically 65-75% EN) and frequency (80-200 Hz) for fine-tuning.

Never use DCEP (DC Electrode Positive) for TIG welding steel. All the heat goes to the tungsten. It will melt into a ball within seconds.

Tungsten Selection Quick Reference

Use 2% lanthanated (blue band) or 2% ceriated (gray/orange band) for both AC and DC work. Pure tungsten (green band) is only for AC on aluminum at lower amperages. Thoriated tungsten (red band) works well on DC but contains low-level radioactivity, so grind it with ventilation.

Grind DC tungsten to a point. For AC aluminum, let the tip ball slightly during welding, or blunt the tip to about 1/3 of the tungsten diameter before starting.

Common Mistakes

Gas flow too high. More gas is not better. Flow rates above 35 CFH create turbulence that pulls air into the shielding envelope. A cup trailing shield or gas lens helps at lower flows and produces cleaner welds than cranking the regulator to 50 CFH.

Wrong cup size. Small cups restrict gas coverage on wider joints. If you see oxidation (gray or black discoloration) on stainless or titanium, step up one cup size before increasing gas flow.

Filler rod too large. Oversized filler quenches the puddle and causes cold lap. Match filler diameter to material thickness, never larger. On thin material, go one size smaller.

How to Read This Chart