TIG Welding Settings Chart: Amps, Tungsten & Gas by Metal

A shop apprentice once spent a whole afternoon fighting a 1/8-inch aluminum butt joint on a machine that was still dialed in for mild steel from the previous job — the puddle would not wet out, the tungsten kept dipping, and nobody could say why. Nine times out of ten the problem is not skill, it is the numbers on the front of the machine: the wrong amperage, polarity, tungsten or gas flow for the metal in front of you.

Why Every TIG Welder Needs a Settings Chart

Most bad TIG welds start at the front panel of the machine, not in the hand holding the torch. When the amperage, tungsten, or gas flow is wrong for the metal on the table, the welder ends up guessing: turn it up a little, try a bead on scrap, turn it down, blame the rod, blame the prep. That trial-and-error loop burns through material, eats clock time, and teaches bad habits, because you never actually know which variable fixed the problem. A reliable settings chart ends the guessing. It gives you a defensible starting number before the arc ever strikes, so the adjustments you make afterward are informed refinements rather than blind stabs.

What TIG actually is

TIG stands for tungsten inert gas welding, and the process is formally called gas tungsten arc welding, or GTAW. The Miller GTAW guidelines define it simply: an arc is struck between a nonconsumable tungsten electrode and the workpiece, and the arc, the puddle, and the electrode are all shielded by an inert gas. The tungsten does not melt away, so the filler metal is added by hand, separately, from a rod. That arc can reach temperatures up to 35,000°F (19,426°C), which is precisely why a few amps in either direction matters so much on thin material.

Why TIG punishes wrong settings more than MIG or stick

Compare that with MIG or stick welding. A MIG gun feeds wire continuously at a set rate, and a constant-voltage power source pulls the arc back in when the operator’s hand drifts. Stick electrodes carry their own shielding in the flux coating and tolerate a fair amount of arc-length sloppiness. TIG has no such safety net: the arc length you hold is set entirely by hand, the shielding is entirely external, and there is no slag hiding an ugly profile. On top of that, Miller notes that GTAW is slower than other processes, has lower filler deposition rates, and demands close hand-eye coordination, which is exactly why precise setup matters more here than it does with aluminum MIG welding or stick. Every mistake you make in setup shows up in the finished bead.

The principal question, answered early

So what settings do you use for a given metal and thickness? The short answer, which the rest of this article fleshes out: identify the base metal and its thickness, choose the polarity (AC for aluminum and most magnesium, DC electrode negative for steel, stainless, copper and titanium), set the amperage for that thickness, then match the tungsten, filler, cup, and gas flow to that amperage. Everything else on the machine is a refinement of that sequence. The chart below simply supplies the numbers so you are not inventing them at the bench.

A useful chart has to resolve six variables at once, because setting only the amperage is a half-setup:

• Polarity and current type — AC, DCEN, or DCEP, the single biggest factor in how the arc behaves.
• Amperage — the heat input, usually expressed as a range for a given thickness.
• Tungsten type and diameter — the electrode must match the current type and the amp range.
• Filler diameter — rod size has to suit both the joint and the heat available to melt it.
• Cup size — the gas nozzle diameter that shapes the shielding envelope.
• Gas flow rate — typically 10 to 25 CFH of argon for most TIG work.

Why no two manufacturer charts agree

Here is the part that surprises people: no single standard sets TIG amperage by thickness. There is no code clause that says 1/8-inch steel gets exactly 60 amps. EWM, Harris, ESAB, Hobart and Panasonic all publish their own recommendation tables, and their ranges for the same thickness differ, sometimes noticeably. Those differences come from assumptions about joint design, travel speed, position, tungsten size, and whether the figure is a cold-start suggestion or a production value. The ESAB TIG welding guide takes the same view: treat published values as guidance to be verified on the job.

That is also why the numbers in this article are given as ranges rather than fixed points, and why you should confirm them with a test coupon before committing to a joint. A chart tells you where to park the dial; experience tells you how far to move it. Clean, dry, and correctly stored material matters just as much as the dial settings, which is why proper aluminum cleaning before welding belongs in the same conversation as amperage. And if you are heading into certified or aerospace work, expect the settings conversation to move into documented procedure territory, as covered in our guide to aerospace TIG welding standards and training. For everything else, the tables that follow give you the numbers, the logic behind them, and the adjustments that keep the puddle where you want it.

How TIG Machine Settings Actually Work

Before you can read any settings chart with confidence, it helps to know what the numbers on the machine are actually controlling. TIG (gas tungsten arc welding, or GTAW) is more settings-sensitive than MIG or stick because almost nothing in the arc is self-correcting. A MIG gun feeds wire at a fixed rate and the arc adjusts; a stick electrode softens and shortens as it burns. In TIG, you are the only variable compensating for everything else, so the polarity, amperage and arc length you start with decide how the weld turns out.

Polarity First: DCEN vs AC

The first switch you set is current type, and it is dictated by the metal in front of you. Carbon steel, stainless, copper, nickel alloys and titanium are all welded on DC electrode negative (DCEN), sometimes called straight polarity. On DCEN, roughly two-thirds of the arc’s heat sits at the workpiece and only a small share at the tungsten, which keeps the electrode cool and pushes heat into the joint. That is why Miller’s GTAW guidelines put it plainly: “Whenever possible and practical, use DC weld output instead of AC weld output.”

Aluminum is the exception, and it is a stubborn one. Aluminum alloys run on AC because the metal forms an oxide layer that melts around 3,700°F while the base metal melts near 1,200°F. On DCEN that oxide would sit on top of the puddle and refuse to break up. On AC, the electrode-positive half of each cycle blasts the surface clean while the electrode-negative half drives heat into the joint. Miller sets a typical AC balance at roughly 70–90% electrode negative: enough cleaning to strip the oxide, enough penetration to fuse the plate. Higher AC frequency narrows the arc cone for deeper, more focused penetration; lower frequency gives a softer, wider arc that is kinder on thin material (Miller). If you have ever tried to run aluminum on DCEN and watched the puddle sit there like oil on water, polarity was the problem. Proper prep matters just as much, which is why Aluminum Cleaner for Welding: How to Prep Aluminum Right is worth a read before your next aluminum job.

Constant Current, Arc Length and the Foot Pedal

Most TIG power sources are constant-current (CC) machines: the machine holds the amperage you set even as the arc length changes. That matters because arc length is really a voltage control. Stretch the arc and voltage climbs, the cone widens, and heat spreads over a larger area; shorten it and the heat concentrates. The pedal lets you manage this in real time. Set the machine to the top of the range you expect, then feather the pedal down as you enter a corner, thin out an edge, or close a crater. The chart gives you the ceiling; your foot does the fine work.

The 1 Amp per 0.001 Inch Rule

The classic starting point is 1 amp per 0.001 inch of material thickness, which gives you 125 A for 1/8-inch steel. Published charts spread wider than that: Harris starts 1/8-inch steel at 125 A while ESAB lists 145 A, so the rule sits at the low end of the real-world range rather than in the middle. It also fails in predictable ways:

• Heat sinking: a heavy fixture or thick backing drains heat, so a butt joint on a heat-sunk plate may need more amps than a T-joint that radiates freely.
• Position: overhead and vertical welds usually need 10–15% less than flat, because gravity works against the puddle.
• Joint type: a wide lap joint on thick material absorbs heat differently than a tight corner on sheet.
• Material: stainless wants less heat than mild steel at the same thickness, and AC aluminum demands its own scale.

Amperage, arc length and travel speed also trade against each other. More amps with a fast travel can produce the same heat input as fewer amps with a slow hand. If your bead is wandering or the arc seems unstable, check the gap before you reach for the dial.

Think of the chart in the next sections as your baseline: pick the polarity, start at the top of the amperage range for the thickness, then let arc length, pedal control and travel speed fine-tune the result on scrap before you commit to the real joint.

TIG Welding Settings Chart for Steel and Stainless (DCEN)

This is the part most welders actually came for, so let’s get straight to it. Mild steel and stainless are both welded on direct current electrode negative (DCEN), also called straight polarity, with 100% argon as the shielding gas. Everything below assumes a transformer or inverter TIG machine running a balanced, clean arc on a flat or horizontal butt or fillet joint. Think of these numbers as your launch pad, not your finish line.

Mild Steel Settings Chart (DCEN, 100% Argon)

Thickness	Amperage	Tungsten	Filler	Cup	Gas Flow
0.030–0.050 in (0.8–1.3 mm)	40–70 A	1/16 in (1.6 mm)	0.045–1/16 in	#6–#8	12–15 CFH
0.060–0.120 in (1.5–3.0 mm)	50–90 A	1/16 in	1/16 in	#8	15–20 CFH
1/8 in (3.2 mm)	125–205 A	3/32 in (2.4 mm)	3/32 in	#8–#10	15–25 CFH
3/16 in (4.8 mm)	140–250 A	3/32–1/8 in	3/32–1/8 in	#8–#10	20–25 CFH
1/4 in (6.4 mm)	150–300 A	3/32–1/8 in	3/16 in	#8–#10	20–30 CFH

Look at how wide that 1/8-inch row is: Harris calls for roughly 125–200 A, ESAB says 145–205 A, and EWM lists 140 A at 3 mm. Same metal, same thickness, three legitimate answers. The reason is that each manufacturer assumes a different joint, a different travel speed and a different amount of preheat in the fixture. Miller’s GTAW guidelines make the same point: the chart is a starting point that you confirm on scrap.

Stainless Steel Settings Chart (DCEN, 100% Argon)

Thickness	Amperage	Tungsten	Filler	Cup	Gas Flow
0.030–0.050 in (0.8–1.3 mm)	35–60 A	1/16 in	0.045–1/16 in	#6–#8	12–15 CFH
0.049–0.095 in (1.2–2.4 mm)	45–80 A	1/16 in	1/16 in	#8	12–18 CFH
1/8 in (3.2 mm)	70–115 A	3/32 in	3/32 in	#8	12–20 CFH
3/16 in (4.8 mm)	100–160 A	3/32 in	3/32–1/8 in	#8–#10	15–22 CFH
1/4 in (6.4 mm)	130–210 A	1/8 in	3/16 in	#10	18–25 CFH

Why stainless runs cooler. Stainless conducts heat roughly four to five times slower than mild steel but melts at a slightly lower temperature, so heat piles up right where the arc sits instead of spreading into the plate. Add the risk of carbide precipitation in the 800–1,500°F sensitizing range and the answer is simple: run about 10–15% less amperage than you would for mild steel of the same thickness. That’s why 1/8-inch stainless sits around 70–115 A while 1/8-inch mild steel wants 125–205 A. Keep travel speed up, keep the puddle narrow, and keep the back side shielded with argon if the joint is a root pass.

How to Read a Range

Here’s the technique that separates a chart user from a chart slave. Set the machine dial at the top of the recommended range, then use the foot pedal to bring the current down as you establish the puddle and back up as you move along the joint. If you set the dial at the bottom of the range, the pedal has nowhere to go and you end up creeping along a cold, pasty bead. The dial sets your ceiling; the pedal rides underneath it.

Modifiers that change the number. The charts above assume a flat-position butt joint with a modest root gap. Three things move the needle:

• Joint type. A fillet weld has more mass pulling heat away than an open butt, so it typically needs the upper half of the range. A corner or edge joint needs the lower half or you’ll burn the edge off.
• Position. Overhead and vertical-up work generally want 10–20% less amperage because gravity is working against the puddle, not with it. For a broader look at position technique, see our All Position Welding Rod Guide.
• Pass count. EWM’s data for steel lists 190 A at 4 mm and 250 A at 5 mm, but both figures describe two-pass square butt welds. Run the root pass at the lower end, let it solidify, then bring the hot pass or cap in at full amperage. A single-pass assumption on a thick joint is one of the fastest ways to get lack of fusion.

One last habit worth building: make the test coupon before the real joint. Run three beads on scrap of the same thickness and heat condition, check penetration with a bend or a cut, and only then strike an arc on the workpiece. That single habit turns a generic chart into your chart for your machine, your tungsten and your gas line.

TIG Settings Chart for Aluminum on AC

Aluminum is where borrowed settings stop working. Carbon steel forgives a machine left on the wrong dial; aluminum does not, because it must run on alternating current (AC), not the DC electrode negative setup used for steel. The current reverses direction dozens of times per second: half the cycle drives the arc into the base metal, the other half flips polarity and blasts the surface clean. That cleaning half is the whole reason AC exists for aluminum.

The reason is one stubborn fact: aluminum oxide melts near 3,700°F while the aluminum underneath melts near 1,200°F. The film forms the instant bare aluminum meets air and sits on the puddle like a ceramic lid. Only the electrode-positive half of AC strips it away, which is why every aluminum process, from Aluminum MIG Welding: The Complete Practical Guide to flux-based methods, has to fight the same battle.

Aluminum TIG Settings Chart by Thickness (AC, 100% Argon)

Starting points for clean, flat-butt 6061 and 5052 plate with a foot pedal:

Thickness	Amps (AC)	Tungsten	Filler	Cup	Argon CFH
0.040–0.060 in (1–1.5 mm)	40–70	3/32 in	3/32 in ER4043	#6–#8	15–20
1/16 in (1.6 mm)	60–90	3/32 in	1/16 in ER4043	#8	15–20
1/8 in (3.2 mm)	85–130	3/32 in	1/8 in ER4043 or ER5356	#8	15–20
3/16 in (4.8 mm)	120–175	1/8 in	3/16 in	#8–#10	17–22
1/4 in (6.4 mm)	170–240	1/8 in	1/4 in	#8–#10	17–22
3/8 in and heavier (9.5 mm+)	230–300	5/32 in	3/16–1/4 in	#10–#12	20–25

Why Aluminum Needs More Amps Than Steel — Until It Doesn’t

Aluminum’s thermal conductivity pulls heat out of the puddle several times faster than steel, so most charts ask for 20–30% more amperage than mild steel at the same thickness. Other respected charts read lower, and both are right: amperage really answers “how fast must I move to keep this puddle fluid?” Heat sinking, joint design and travel speed matter as much as thickness.

• EWM: 75 A at 1 mm, 90 A at 2 mm, 125 A at 3 mm, 160 A at 4 mm.
• Panasonic: 60–80 A for a 1.6 mm butt joint, jumping to 260–300 A at 6 mm.
• Hobart/Miller: 1/8 in 6061 joints from 80 A to 125 A depending on geometry.

EWM assumes good heat sinking and short, fast beads; Panasonic’s 6 mm figures assume heavy, clamped stock acting as a giant heat sink. Read a chart as a range, set the machine near the top of it, and let the pedal bring the amperage down once the puddle forms.

Joint-Specific Values: Butt, T-Joint, Lap and Corner

Hobart and Miller’s figures for 1/8 in 6061 show how much geometry changes the heat needed:

Joint type	Amperage
Butt joint	90–120 A
T-joint (fillet)	100–125 A
Lap joint	90–110 A
Corner joint	80–90 A

All four assume 3/32 in tungsten, 1/8 in 5356 filler and 15–20 CFH argon. The T-joint runs hottest because two plates at a right angle trap heat in the corner; the corner joint runs coldest because both edges radiate freely. The same logic keeps tube, thin sheet and out-of-position work low on the chart.

AC Balance and Frequency Starting Points

Two machine settings matter on AC beyond raw amperage:

• AC balance: the split between cleaning (electrode positive) and penetration (electrode negative). Set roughly 65–80% electrode negative — enough penetration with cleaning to lift the oxide. Drop the EN percentage on dirty, oxidized or cast material, then back off after prepping. Too much EP overheats and blunts the tungsten; too little leaves a black, sooty bead that never wets out.
• AC frequency: sine-wave machines sit at 60 Hz and give a wide, soft arc. Inverter machines climb to 100–200 Hz for a narrower, more directional arc on thin edges and out-of-position work. Start around 100–120 Hz for general sheet and resist the urge to max it out — higher frequency also narrows penetration.

Matching Filler to the Aluminum You’re Welding

ER4043 (about 5% silicon) is the forgiving general-purpose rod: lower melting point, fluid puddle, strong resistance to solidification cracking, and the usual pick for 6xxx alloys, castings and Alloy Wheel Welding: A Comprehensive Guide to Safe and Effective Aluminum Wheel Repair. ER5356 (about 5% magnesium) is stronger and stiffer, matches the 5xxx series, and is standard for Aluminum Boat Welding: The Complete Guide for Strong Hull Joints and 5052 fabrication, but it cracks more readily with poor fit-up. If the part will be anodized, filler choice changes the final color, so confirm the spec first.

None of these settings save a contaminated surface: wipe with a dedicated Aluminum Cleaner for Welding: How to Prep Aluminum Right, then scrub oxide with a dedicated stainless wire brush. The chart only works on metal the arc can reach.

Choosing and Preparing the Tungsten Electrode

The tungsten is the only part of a TIG setup that never joins the puddle. It is non-consumable, it just holds the arc together, and yet picking the wrong one is the fastest way to ruin a settings chart that was otherwise correct. Too thin for the job and it balls up, wanders and dips. Too thick and it hogs current you never intended to put into the joint. Ground the wrong way, the arc throws off to one side no matter how steady your hand is. Matching tungsten type, diameter and prep to the amperage range in your chart is the step most beginners skip.

Reading the AWS Colour Codes

Tungsten alloys are colour-banded at the back end so you can identify them at a glance, and the banding roughly follows the AWS classification system. The common types fall like this:

Tungsten type	Band colour	Best suited to
2% lanthanated (EWLa-2)	Blue	DC and AC, the all-round shop default
2% ceriated (EWG)	Gray / orange	DC on steel and stainless, thin-sheet work
2% thoriated (EWTh-2)	Red	DC on carbon steel, high-amperage production
Pure tungsten (EWP)	Green	AC on aluminium with older transformer machines
Zirconiated (EWZr-1)	Brown	AC on aluminium and magnesium
1.5% lanthanated	Gold	AC on aluminium, low-amperage TIG
1% lanthanated	Black	Thin material on both current types

If you only stock one box, make it 2% lanthanated blue. It starts easily, tolerates both polarities and holds up across the amperage span most shops see. Ceriated gray is the sensible second choice for precision DC work, and thoriated red still has a following in heavy carbon steel fabrication where arc rigidity matters. Modern Miller GTAW guidelines note that pure and zirconiated tungsten belong to AC work, while alloyed types carry far more current before they degrade.

Match Tungsten Diameter to the Amperage Range

This is where the chart and the tungsten box have to agree. Miller publishes a simple amperage capacity table for ceriated, lanthanated and thoriated tungsten in argon, worth taping inside your cabinet:

Tungsten diameter	DCEN range in argon
1/16 in (1.6 mm)	70–150 A
3/32 in (2.4 mm)	150–250 A
1/8 in (3.2 mm)	250–400 A
5/32 in (4.0 mm)	400–500 A

Read it alongside the thickness column of your settings chart. If the chart calls for 60–90 A on 16-gauge steel, you are in 1/16 in territory. Anything from roughly 1/8 in to 3/8 in plate sits comfortably on 3/32 in, which is why that size sells in bulk. Reserve 1/8 in for heavy plate, castings and long out-of-position runs where the electrode needs thermal mass. Going oversize is not automatically safer: a tungsten carrying far less current than its rating holds a wider, softer arc than you want on thin material.

Grinding: Angle, Direction and the Wheel

For DCEN work the ideal included grind angle is 15°–30°, with 30° the recommended starting point. The detail people miss is direction: grind lengthwise along the electrode, never in a radial roll, so the scratch lines run parallel to the current path and keep the arc focused instead of dancing between ridges. Use a fine wheel dedicated to tungsten only, because a wheel previously used for steel embeds iron in the tip and guarantees contamination, and finish with a light break on the point so it does not flake. On AC, a slightly blunter or lightly flattened tip survives the cleaning half-cycle better than a needle point. Precision-minded shops, especially in aerospace TIG welding, treat grinding angle and stick-out as documented procedure variables rather than personal habits.

The Thoriated Tungsten Dust Caution

Thoriated tungsten (EWTh-2) contains 1.70–2.20% thorium, a low-level radioactive alloying element. The metal is safe to handle, but grinding produces a fine dust that should not be breathed or scattered across the bench. Use local exhaust ventilation at the grinder or wear a respirator, wet-wipe the area instead of sweeping it dry, and label the container. If you would rather not manage that exposure, ceriated and lanthanated electrodes perform almost identically in most applications, which is why they are now recommended more often. Dust control pairs with disciplined aluminium surface preparation, since a contaminated puddle is usually why a good tungsten gets dipped and destroyed. The same ventilation discipline applies more broadly under OSHA’s welding, cutting and brazing standard.

Note: Regrind a contaminated tungsten by snapping the affected tip off in the collet, then grinding fresh on the dedicated wheel. Never pull a dipped tungsten out and strike an arc again on the same tip — the embedded aluminium or steel will keep spitting into your weld.

Shielding Gas, Cup Size and Flow Rate Settings

Shielding gas looks like the least technical number on a TIG machine, so many welders set it once and forget it. The gas does three jobs at once: stabilizing the arc, shaping how it spreads into the puddle, and keeping oxygen and nitrogen off the molten metal and white-hot tungsten. Get this wrong and no amperage tuning will rescue the weld.

Why 100% Argon Is the Default

For most TIG work, the cylinder says argon and nothing else. Pure argon starts easily at low amperage, runs on AC and DC, and gives a soft arc that forgives small mistakes. It covers mild steel, stainless, aluminum, copper and titanium across every thickness in this chart, costs less than any blend, and every supplier stocks it. This AllGas Welding Supply: Gases, Services & Safety Guide covers cylinder sizes and regulators.

Two blends earn a place for specific jobs:

• Argon-helium. Helium ionizes at a higher voltage, so the arc runs hotter, penetrates deeper and lets you travel faster on thick aluminum and heavy steel. The trade-offs: fussier arc starts, a louder arc, and roughly twice the flow rate to keep the puddle covered, as Miller’s GTAW shielding gas guidelines explain.
• Argon-hydrogen (2–5% H₂). A small hydrogen addition stiffens and cleans the arc on austenitic stainless, improving penetration and bead contour. Keep it off ferritic and martensitic steels, and never use it on aluminum, where hydrogen feeds porosity and cracking.

Flow Rate: Why More Is Not Better

Typical TIG argon flow sits between 10 and 25 CFH, and manufacturer numbers cluster tighter than most people expect:

Setup	Recommended flow
General TIG, 100% argon	10–25 CFH (about 5–12 L/min)
EWM, 1–4 mm tungsten	5–10 L/min (11–21 CFH)
Harris, 1/16–1/8 in steel work	20 CFH (about 9.5 L/min)
Argon-helium blends	Roughly twice the argon flow

Cranking the regulator to 40 CFH because “more shielding must be safer” is a common shop mistake. Above a certain velocity the gas stops being a smooth, parallel column (laminar flow) and starts swirling with air (turbulent flow). Turbulence does not push air out; it draws oxygen and nitrogen into the shielding envelope and straight into the puddle. Typical symptoms: a dull gray weld that looked acceptable wet, fine porosity, or a sugared stainless root. Too little flow is just as damaging: the hot tungsten sits exposed and oxidizes into a chalky blue-gray point that destabilizes the arc.

Two variables change that number:

• Gas outlet distance. The practical rule is about 1/2 inch of tungsten stick-out per 10 CFH: push the tungsten out and you need more flow to keep the column intact.
• Cup size. A #5 cup and a #12 cup do not give the same coverage. Larger cups and gas lens bodies spread the gas wider, holding coverage at longer stick-outs and out-of-position angles where a small cup loses the shield.

Gas Lens Cups: Better Coverage at the Same Flow

A gas lens swaps the standard cup for a stack of fine screens that straightens the flow into a long, stable, laminar column. The gains are better puddle visibility and the ability to weld with the cup an inch or more from the joint at your usual flow. It also forgives a longer stick-out, which helps on tight fillets and T-joints. Coverage only works on clean metal: oil, drawing compound and aluminum oxide outgas faster than argon can sweep them away, so prep matters as much as flow. See Aluminum Cleaner for Welding: How to Prep Aluminum Right for the sequence.

Pre-Flow, Post-Flow and Back-Purging

Pre-flow, about a half second to a second on an inverter, floods the joint with argon before the arc strikes so the tungsten does not oxidize at start-up. Post-flow matters more: roughly one second per 10 amps protects the still-hot tungsten and the cooling crater while they stay reactive. Too little leaves a discolored, blunted tip that makes the next arc start erratic; too much simply wastes a $30 bottle of argon.

Back-purging applies the same idea under the weld. Argon behind the root of a stainless, titanium or duplex joint prevents sugaring on stainless and stops titanium forming a hard, brittle oxide layer. Carbon steel and aluminum do not need it, since neither forms a damaging root oxide.

Argon and helium are odorless and heavier than air, so they pool in pits, tanks and trenches and displace oxygen; OSHA’s 1910.252 requires ventilation or air-supplied respirators where inert-gas welding happens in a confined or poorly ventilated space. OSHA also notes that gas tungsten arc welding produces ultraviolet radiation at intensities 5 to 30 times that of shielded metal arc welding, so screens, leathers and the correct lens shade are part of the setup. A buyer’s reference like this Airgas Welding Supplies: The Complete Buyer’s Guide keeps cylinder sizes and regulators consistent.

Filler Rod Selection to Match Your Base Metal

Amperage gets the attention in a settings chart, but the filler rod is the other half of the equation. The arc melts the base metal; the rod supplies the alloy that solidifies into the bead. Run perfect settings with the wrong classification and you can still end up with a brittle joint, a cracked corner, or a bead that never wets out. TIG filler carries an AWS classification: ER means “rod or wire for gas shielding welding,” and the numbers describe the matching base metal.

Filler Chart by Base Metal

Base Metal	TIG Filler (AWS)	When to Use It
Mild steel, low carbon steel	ER70S-6, ER70S-3, ER70S-2	ER70S-6 for mill scale or light rust; ER70S-3 or ER70S-2 for clean, oil-free sheet
4130 chromoly tube	ER80S-D2	Standard choice for welded 4130 frames, roll cages and aircraft structure
304 stainless	ER308L	General austenitic stainless work, the everyday rod
316 stainless	ER316L	Marine, chemical and food-grade 316 fabrication
Stainless to carbon steel	ER309L	Dissimilar joints and stainless overlay on mild steel
6061 and other 6xxx aluminum	ER4043 or ER5356	4043 for crack resistance; 5356 where strength or anodizing color matters
5083 aluminum (over 2.5% Mg)	ER5356 only	Never a 4xxx rod on this alloy; magnesium content makes 4043 unsuitable
Titanium (commercially pure / 6Al-4V)	ERTi-2 / ERTi-5	Match the filler grade to the titanium grade being welded
Copper and copper alloys	ERCu, ERCuSi-A	ERCu for deoxidized copper; ERCuSi-A (silicon bronze) for joining brass and bronze

Manufacturers publish these matches in their filler selection tables, and they rarely disagree. If you are welding structural alloy steel, our guide to alloy steel welding electrodes covers the same matching logic for other processes.

Matching Rod Diameter to Thickness and Tungsten

Filler diameter should track joint thickness more than anything else. The practical ranges published by Harris and EWM break down like this:

• 1/16 in rod: material from 1/16 to 1/8 in thick — sheet, thin tube, most repair work.
• 3/32 in rod: the bridge size, comfortable from about 1/8 to 3/16 in.
• 1/8 in rod: material from 3/16 to 1/4 in and heavier, where the puddle needs real volume.
• 5/32 in and up: heavy plate, multi-pass roots, high-deposition work.

Also keep the rod no larger than roughly the tungsten diameter and never smaller than about a third of it. A 1/16 in tungsten feeding a 1/8 in rod chills the arc zone; a heavy rod on a thin joint means you crank the pedal, and the extra current buries an edge never meant to take it.

Keep Aluminum Filler Clean and Dry

Aluminum rod is the only filler that punishes sloppy storage this way. Oxide, moisture and oil picked up from a shop floor or bare hands are a listed cause of porosity in Miller’s common TIG weld problems. Wipe rods with a lint-free cloth and solvent, keep them in a closed drawer or rod bag rather than on the floor, and use fresh-cut lengths; a stub that rolled under a bench is not worth the risk on a visible weld. This pairs with the surface step in our aluminum cleaner for welding guide: clean metal and clean rod attack the same problem.

Dab Rather Than Dunk

Feeding technique is a settings decision in disguise, because it changes how much heat the joint actually sees. Touch the rod to the leading edge of the puddle, add a small drop, pull back into the gas envelope, and repeat. That is the dab. Dunking — burying the rod and stirring — does three bad things at once: it shields the tungsten so the puddle stalls, it chills the melt with a cold mass of filler, and it pulls rod tip contaminants straight into the weld. Keep the rod tip inside the shielding gas even when it is out of the puddle, and add filler in rhythm with travel speed rather than ahead of the arc. In overhead and vertical positions, where gravity fights the bead, thinner rod and a lighter dab keep the amperage honest; our all position welding rod article explains the same feed discipline from the stick and MIG side.

The rule of thumb is simple: identify the base metal, pick the matching AWS filler, size it to the thickness, then confirm the chart’s amperage still behaves with that rod in hand. If the puddle will not take the rod, the settings and the filler are telling you the same story — one of them needs to change.

Advanced Settings: Pulse, Slope Control, Balance and Frequency

Once the base numbers from the TIG welding settings chart are correct, advanced controls are what take a bead from passable to clean. On modern inverters, upslope, downslope, post-flow, pulse, AC balance, and AC frequency all have their place, but only when used for a specific problem.

Upslope, Downslope and Post-Flow

Upslope ramps current up at arc start, allowing the puddle to form gently without shocking cold metal. Downslope does the opposite at arc-off, tapering current down to give the shrinking puddle time to be fed with filler. Skipping it is one of the easiest ways to create a crater, which is among the most commonly listed causes of cracking in TIG troubleshooting, especially on aluminum and hardenable steel.

For starting points, use around 2 to 4 seconds of downslope on steel and stainless, and closer to 4 to 7 seconds on aluminum. Be sure to add a final dab of filler while current is still falling. From there, post-flow takes over. A widely used guideline is 1 second of post-flow per 10 amps, capping out around 15 to 20 seconds. This blanket of argon protects both the tungsten and the hot bead until it drops below glowing temperature.

Pulsed TIG: Peak, Background and Frequency

Pulsed TIG alternates between a high peak current to melt the puddle and a low background current to allow it to solidify. Only three numbers need attention:

• Peak amperage: This should be close to what you would run in continuous mode for your thickness and joint.
• Background amperage: Most manufacturers suggest 20 to 50 percent of peak to keep the arc alive without adding excessive heat.
• Pulse frequency: For general work, run between 0.5 to 10 pulses per second. One to 2 Hz will give a stacked-dime look at slow travel, while 5 to 10 Hz tightens the bead for faster travel.

Pulse shines on thin sheet, out-of-position welds, heat-sensitive stainless, and long seams where distortion is a concern. These benefits are why it’s standard practice for Aerospace TIG Welding: Standards, Techniques, and Training where dimensional accuracy matters. Be cautious with over-pulsing. If the bead looks stacked, but the root isn’t tying in, drop the frequency, raise the background current, or speed up. Pulse is a heat management tool, not a replacement for proper amperage.

AC Balance and AC Frequency for Aluminum

Two AC-specific controls dictate how your arc behaves on aluminum. AC balance splits time between the cleaning half and the penetrating half of each cycle. Per Miller’s balance control guidance, more electrode-negative time increases penetration, while more electrode-positive time increases cleaning. For clean metal, start around 65 to 70 percent electrode-negative. Shift towards more electrode-positive time when heavy oxide is present, and always verify your machine’s display convention, as some read percent electrode-positive while others read percent electrode-negative.

AC frequency changes the arc width. At 60 Hz, the arc is broad and soft. Increasing it towards 200 Hz tightens and focuses the arc for narrow fillets, corners, or thin edges. Dropping to around 80 to 100 Hz will spread the heat for a wider, shallower puddle. No matter the settings, thorough work with an Aluminum Cleaner for Welding: How to Prep Aluminum Right will still be needed before striking an arc.

Spot Timer and Independent Amplitude Control

For repetitive work, a spot timer will hold the arc for a preset interval before shutting off and running post-flow automatically. It’s ideal for consistent tacks on sheet assemblies. On higher-end inverters, independent amplitude control takes this a step further by allowing the electrode-positive and electrode-negative currents to be set separately. This lets you maintain strong cleaning on a rough casting, whilst limiting penetration to avoid burning through thin walls.

Common TIG Settings Mistakes and How to Troubleshoot Them

Every bad TIG weld leaves a clue. Once you learn to read the bead instead of blaming your hands, most “technique problems” turn out to be number problems: too many amps, too little gas, an arc held too long, or a joint that was never clean to start with. The table below maps the symptoms you will actually see on the bench to the setting that caused them and the correction that fixes it.

TIG Troubleshooting Chart: Symptom, Cause, Fix

Symptom	Likely settings cause	Fix
Tungsten dips and contaminates the bead	Amperage too high for the tungsten diameter, arc length too long, filler rod touching the electrode	Step up one tungsten size, shorten the arc, regrind the tip, restart with clean tungsten
Porosity (pinholes) in the weld	Travel speed too fast, freezing the puddle before gas escapes; damp or dirty filler; low, turbulent or drafty gas flow; contaminated shielding gas	Slow down, confirm flow at the chart value, wipe the rod, check hose and cup connections
Lack of fusion or cold lap	Amperage below the chart range, arc too long, travel too fast, oxide left on aluminum	Raise into range, hold the arc at the leading edge, clean thoroughly before welding
Undercut along the bead toe	Excess current combined with too-fast travel and filler not carried to the crater wall	Reduce current, slow the travel speed and work filler into the edge
Bead sitting on top, not wetting out	Too little heat for the joint, or an unbroken oxide film on aluminum	Set the machine to the top of the chart range and let the pedal bring it down; grind and clean the surface
Arc wandering, snapping or drifting	Excessive gas flow causing turbulence, an open shop draft, contaminated tungsten, or grind grooves running the wrong direction	Drop flow to spec, block the draft, regrind longitudinally along the electrode
Sugaring/oxidation on stainless root	Too much heat input and no back-purging gas on the underside of the joint	Purge the root, reduce amperage, add trailing argon coverage
Burn-through on thin sheet	Machine set at the top of the range with no pedal control, long arc, slow travel	Set lower, control with the foot pedal, add filler more often to absorb heat
Crater cracks at the stop	No downslope, arc pulled away too fast, crater left unfilled	Enable downslope, stay on the pedal while filling the crater, then release for post-flow

Four variables explain most of these rows: cleaning, travel speed, arc length and polarity. Excessive electrode consumption is a good diagnostic tell, and troubleshooting guides trace it to inadequate gas flow, an electrode sized too small for the current, reversed polarity, or a contaminated tip. If your tungsten is eroding into a ball or turning black mid-run, check gas first, then tungsten diameter, then which side of the clamp the polarity is on.

The Polarity Error That Ruins Aluminum Joints

The single most expensive settings mistake on aluminum is running it on DC electrode negative. Without the AC cleaning half-cycle, the arc cannot break down aluminum oxide, which melts near 3,700°F while the base metal gives way around 1,200°F. The filler then mixes with films of partially melted oxide and drags that contamination into the bead, producing a gray, sooty, porous weld that looks like a gas problem but is really a polarity problem, as Miller’s GTAW guidelines explain. If you are prepping aluminum, a dedicated aluminum cleaning and etching routine before the arc strikes matters as much as the numbers on the front panel.

The same logic applies to the other settings-heavy symptoms. Porosity is usually gas timing rather than gas volume: a puddle moved too quickly traps hydrogen and air before they can rise out, and damp filler rod releases exactly the hydrogen you do not want. Undercut is current plus speed, not hand position. Burn-through is almost always an arc held too long or a machine set too high for a pedal that never gets used. For a fuller walkthrough of these symptoms, Miller’s common TIG weld problems guide and a standard TIG troubleshooting chart are worth keeping near the machine.

Work the diagnosis in order: confirm polarity, confirm the metal is actually clean, confirm the gas is flowing and uninterrupted, then set amperage to the chart value for that thickness and joint. Re-test on scrap, adjust one variable at a time, and write down what worked. That short loop resolves the overwhelming majority of TIG defects before they ever reach the finished part.

Safety, Codes and Final Takeaways for Using a TIG Welding Settings Chart

You can dial in every number in this chart perfectly and still end up with a failed weld — or a failed welder — if the settings conversation stops at the machine front panel. Gas tungsten arc welding is unusually demanding on the operator’s body: it is hot, it is bright, and it is one of the few processes where the arc itself is close enough to your face that the details of protection genuinely matter. Before we close, here is the safety and code framework that sits alongside every amperage number in this article.

ventilation: the 2,000 CFM Rule

OSHA 29 CFR 1910.252(a)(2) sets the baseline for indoor TIG work: where a welding area has ceilings lower than 16 feet or contains less than 10,000 cubic feet of air per welder, you need mechanical ventilation sufficient to keep fume concentrations below the permissible exposure limits — a minimum of 2,000 cubic feet of air per minute per welder. Push that number up dramatically when welding coated, plated or dirty metal, because the fume chemistry changes with the coating, not the base metal. Local exhaust at the torch, positioned as close to the arc as the work allows without disrupting the shielding gas, beats general shop air movement every time. TIG is often sold as the “clean” process, and it is cleaner than stick — but it still produces fumes, and the IARC has classified both welding fumes and welding UV radiation as Group 1 carcinogens.

UV, Burns and Eye Protection

OSHA 1926.353(d)(1) notes that GTAW produces ultraviolet radiation roughly 5 to 30 times more intense than shielded metal arc welding. That means a shade 10–13 lens is not automatically enough and a nearby bystander can get a sunburn-like skin burn or arc flash in seconds. Full leathers, no bare wrists, a curtain around the station, and a helmet shade matched to your amperage (Miller’s GTAW guidelines suggest shade 8 at low amps scaling up with current) are non-negotiable. Never look at a stray arc, including when striking on scrap.

Confined Spaces, EMF and Grinding Dust

Confined space TIG work triggers an entirely separate permit program with atmospheric testing, attendants and rescue plans; a chart does not help you there without a procedure. There is also the electromagnetic field issue that Miller addresses in its GTAW guidelines: keep cables twisted and routed close together, do not drape the torch cable over your body or loop it around your torso, and connect the work clamp as near the weld as possible. Anyone with a pacemaker or implanted defibrillator must consult their cardiologist before welding. Finally, grinding thoriated tungsten creates radioactive dust — use a dedicated, ventilated grinder, never grind it on the same wheel you use for steel, and treat the dust as hazardous material.

The Complete Workflow in Seven Steps

Here is the decision sequence every weld in this article follows:

1. Identify the metal — carbon steel, stainless, aluminum, or an alloy like 4130, and its actual measured thickness.
2. Pick polarity — DCEN for steel and stainless, AC for aluminum and magnesium.
3. Read the amps — use the chart’s thickness row as your starting point, remembering the 1 amp per 0.001 inch rule only as a sanity check.
4. Match tungsten and filler — diameter to amperage, alloy to base metal, and match filler diameter roughly to tungsten diameter.
5. Set cup and flow — cup sized to the joint geometry, flow at 15–20 CFH argon for open work, more only when the torch angle or joint depth demands it.
6. Test on scrap — run a coupon of the same thickness in the same position before touching the real joint.
7. Adjust one variable at a time — arc length, travel speed, then amperage, and record what worked.

That last step is the point of the entire chart. No published table accounts for your machine’s calibration, your torch’s heat sink, your ambient drafts, or how you hold the pedal. If you are moving into aluminum-heavy or code work, structured training such as an aerospace TIG welding program teaches exactly this translation from procedure sheet to real puddle, and the same discipline applies whether you are repairing boat hulls or building aluminum boat welds.

Treat the numbers in this guide as a qualified starting point, not gospel. Set the machine from the chart, run a test coupon, inspect it for fusion, porosity and color, and nudge from there. A welder who adjusts from evidence will always outperform one who memorizes a table — the chart simply gets you close enough to start learning faster.

Frequently Asked Questions

What is the basic rule of thumb for TIG welding amperage?

A common shop rule is about 1 amp per 0.001 inch of material thickness, so 1/8-inch plate starts near 125 amps. It works as a starting point on thin steel but runs too high on thick sections, so always confirm against a manufacturer chart and a test coupon.

What polarity should I use for TIG welding steel versus aluminum?

Weld carbon steel, stainless, copper, nickel and titanium on DC electrode negative (DCEN). Aluminum requires AC, because the electrode-positive half of each cycle strips the tough aluminum oxide layer while the electrode-negative half drives penetration.

How much argon flow does TIG welding need?

Most bench TIG work runs 10-25 CFH (roughly 5-12 L/min) of 100% argon, with 15-20 CFH covering typical mild steel jobs. Increase flow slightly for out-of-position or drafty work, but never crank it up — excessive flow creates turbulence that pulls air into the puddle.

Why does aluminum need different settings than steel?

Aluminum carries a tenacious oxide layer that melts around 3,700°F while the base metal melts near 1,200°F, so it needs AC for cleaning and usually a different amperage than steel of the same thickness. Aluminum also dissipates heat quickly, so settings must be paired with fast, decisive travel.

Which tungsten should I use for TIG welding?

2% lanthanated (blue band) is the best all-around choice because it starts easily on both AC and DC and holds a point. Ceriated is good for low-amp DC starts, thoriated (red) is durable but produces radioactive grinding dust, and pure or zirconiated tungsten is mainly for AC on older transformer machines.

Why is my tungsten sticking to the workpiece or getting contaminated?

Usually the current is too high for the tungsten size, the arc length is too long, or the electrode is touching the puddle or filler rod. Drop amperage or step up tungsten diameter, shorten stick-out to no more than one cup diameter, and regrind the tip lengthwise at 15-30 degrees.

Why am I getting porosity in my TIG welds?

Porosity comes from inadequate shielding — a draft, a leaking hose, too little or too much gas flow — plus damp or oily filler rod and dirty base metal. Slow your travel speed slightly so the puddle is not frozen before gas escapes, and check the entire gas path for leaks.

Do I need a formal weld procedure for TIG work?

For structural code work, yes. AWS D1.1 does not list GTAW among its prequalified processes, so a qualified welding procedure specification is required; a settings chart is only a starting point for coupons and non-code fabrication.