How Does TIG Welding Work? A Complete Guide To The GTAW Process

Three choices decide whether a TIG weld looks like a showroom sample or a spatter-covered mess: the tungsten, the shielding gas, and the filler you feed in, or choose not to. Each punishes sloppy selection.

Tungsten Electrode: The Heart Of The Arc

The tungsten electrode is non-consumable: it carries current and forms the hot tip of the arc without melting into the weld, so TIG lays down a clean weld with no filler contamination. Its melting point of about 3,422°C plus excellent electrical and thermal conductivity make that possible, but pure tungsten is not for daily work. Most shops run thoriated (roughly 1% or 2% thorium) or ceriated (about 0.8% or 2% cerium) electrodes, both EWTP-type alloys under the AWS classification system. The dopants lower the tungsten’s work function, so the arc starts reliably and holds steady at low amperage.

Ceriated is more common because it is not radioactive and performs well on AC. Thoriated still edges it on pure DC and fine work at lower heat, so it needs careful handling and closed storage under local radioactive material rules.

Choosing A Tip: Diameter And Geometry

Tungsten diameter sets the current ceiling and how much heat you can put into the workpiece: 0.010 to 0.040 in for thin material and light-gauge sheet, 3/32 in as the general workhorse, 1/16 in and 5/32 in for heavier plate, castings, and most aluminum.

Geometry is the cone angle and the diameter of the ground flat. A sharp point focuses the arc into a narrow, intense beam for thin material and precision work but wanders at high amperage; a flat end spreads heat wider, which suits heavy material, filler-heavy passes, and aluminum.

Use the smallest electrode that can carry your amperage without overheating. A cherry-red tip with an erratic arc means you are asking too much of the tungsten.

Grinding Tungsten: The Step Most People Rush

Grind on a dedicated grinder with a diamond wheel, never a bench grinder or belt sander: a green wheel or belt heats the tip, smears the metal, and leaves grooves that trap contamination. Grinding shapes the tip, removes contamination from the previous weld (the number one cause of tungsten contamination problems), and creates the heat-transfer gradient that keeps the arc steady. Grind in one direction only, along the electrode’s axis. A mirror polish is not the goal; a fine, consistent grind with shallow lines is.

Shielding Gas: Why Argon Rules

Shielding gas does three jobs: it protects the hot tungsten from oxidation, protects the molten pool from atmospheric contamination, and carries heat from the electrode to the workpiece in a controlled column.

Argon is the most widely used TIG shielding gas because it does all three well: heavier than air so it blankets the puddle, a good conductor of heat so the arc stays stable, and chemically inert, which is why it welds titanium and stainless cleanly.

• Helium gives a hotter, more concentrated arc with better penetration and is standard for aluminum and magnesium; pure helium suits very thin, heat-sensitive alloys.
• Argon-helium mixes (75/25, 80/20) widen the current range on aluminum when you need more heat without burning through.
• Argon with a small hydrogen addition (99.98% argon plus hydrogen) improves wetting and reduces oxidation on stainless and nickel alloys.

Two cautions. Never run MIG shielding gas, which contains a little CO2, through TIG argon on the same regulator and hose; it chews up the tungsten and pits the weld. TIG cylinder and fitting threads also differ from MIG and Stick fittings, so regulators are not interchangeable. Running both processes in one shop? Plan separate regulators and hoses, and read this guide to welding gases and supply first.

Filler Metal: When To Add It And When Not To

Filler is optional in a GTAW weld. A weld with no filler at all is an autogenous weld: the base metal melts, flows together, and solidifies, which on thin sheet, close-fitting tube joints, and repair work can be strong and clean with no filler to discolour the bead. Add filler when the gap is too wide for the base metal to bridge alone, when you need to build up bead cross section, when the joint will be machined or heavily loaded, or when code requires it. Filler also controls dilution, and on dissimilar joints you can pick a composition sitting between the two base metals instead of a brittle mixture.

Filler follows the base metal closely, and the AWS filler metal specifications are the reference to keep on hand, as outlined in the AWS standards and publications library:

• Carbon and low-alloy steel: ER70S-6 general workhorse, ER70S-5 higher deposition rate.
• Stainless steel: ER308L for 304 and 316, ER309L for stainless to carbon steel, ER316L for moly stainless.
• Aluminum: ER4043 general purpose, ER5356 for higher-strength joints and better heat tolerance.
• Magnesium: ER5356 or ER5189, matched to the alloy.
• Copper alloys: ERCuSi-A for most bronze and brass work.

Match filler diameter to material thickness, not to puddle size. A 3/32 in rod on 16 gauge stainless floods the pool, chills it, and buries the arc; thin sheet wants 1/16 in or smaller. Feed the rod into the leading edge of the puddle rather than dropping it in. For aluminum, keep the rod cold, since a warm rod picks up oxide and misbehaves. Our walkthrough of aluminum prep goes deeper. And keep filler clean, dry, and free of oil, paint, and grease: contamination ends up in the center of the bead, where you cannot see it until you cut the joint open.

How These Three Choices Work Together

Tungsten sets the arc’s character and current capacity, tip geometry decides whether that arc concentrates into a tight bead or spreads into a wide hot wash, gas controls how much heat lands on the work, and filler decides how much metal ends up in the joint. When a weld goes wrong, start here: too-large tungsten or a contaminated tip gives a wandering arc, wrong gas or flow gives oxidation and porosity, dirty filler gives inclusions.

For the wider picture on consumables and process control, the Lincoln Electric TIG process and theory library is an excellent reference, and the American Welding Society covers classification, qualification, and filler specifications in detail.

Joint Preparation, Positioning, And TIG Welding Technique

TIG welders separate themselves on arc control, and that starts with joint preparation, not the torch.

Cleaning Comes First

TIG has no flux, so every oxide, oil film, and coating is still there when you start, and contamination is a leading cause of weld defects.

Clean the last 25 to 50 mm on either side of the joint, and never use a wheel or brush that has touched copper:

• Stainless steel: stainless wire brush and degreaser, plus a light flap disc pass to remove heat tint.
• Aluminum: oxide reforms within minutes, so grind right before welding and use a dedicated aluminum cleaner. Prepping aluminum properly covers why it differs from steel.
• Carbon steel: acetone or degreaser, with all rust, mill scale, and primer removed.

Joint Design And Fit-Up

Without flux, joint design matters more in TIG than in stick or MIG work, and you need room to see the puddle and reach the filler rod.

Fit-up is where first attempts fall apart. Clamp or jig the pieces so the gap stays constant, because movement after tacking causes porosity, undercut, or an erratic arc. Tack small and clean, and grind a proud tack flush before welding over it. Aluminum contracts as it cools, so clamp long butt joints tight and allow for shrinkage.

Torch Angle, Arc Length, And Amperage

Torch angle sets where the arc force and filler land. Flat, hold the torch 10 to 15 degrees off vertical, leaning toward travel for better penetration and a flatter bead with less push. In corners and tee joints, tilt so the arc points into the corner and splits between both members.

Arc length is the distance between tungsten tip and workpiece, and it should be short. A short arc concentrates heat, improves control, and keeps shielding gas over the puddle; a long arc oxidizes the tungsten and lets air in, causing porosity. Use the TIG arc length reference as a baseline of one to two tungsten diameters, and hold it consistently for shielding and puddle visibility.

Amperage sets how much heat enters the workpiece and how fast the puddle forms. Too low and the pool is sluggish; too high and it boils, pushes molten metal backward, burns thin material, and can crack. Start near one amp per thousandth of an inch of thickness for stainless and mild steel.

Adding Filler And Controlling The Puddle

Most TIG welds use filler rod, but plenty of good ones are autogenous, with no filler at all. Thin sheet and joints where the base metal flows on its own need nothing added.

Feed filler into the leading edge of the puddle, not onto the arc. Touch the rod to the puddle ahead of travel, let it melt, and move it away. Dipping it into the middle of the pool traps gas, a leading cause of porosity.

For 16 gauge and thicker material, use rod roughly matching the base metal thickness, long enough to keep your hand clear of the heat. The all-position rod guide covers diameter and alloy choices.

The puddle is your feedback system: a smooth, quiet, mirror-like oval trailing slightly behind the arc. If it boils or throws spatter, your amperage is too high or the gas flow is wrong. If it is small and sluggish, drop the amperage or add filler sooner.

Travel speed is the final dial. Too fast leaves a wide, cold, poorly fused bead with a dimpled, oxidized surface; too slow dumps heat into the plate and distorts thin material. Aim for a puddle about one and a half times the width of the finished bead, speeding up as the pool widens.

Welding In Different Positions

• Flat is where you learn everything: gravity helps filler flow, the arc is stable, and you can watch the pool closely. Master flat first, even if your real work is vertical.
• Horizontal is nearly as forgiving. The puddle sits slightly ahead of the arc, so push it along rather than chasing it, angle the torch slightly down, and feed filler from the top.
• Vertical up is the most common position for pipe and tube work and the hardest to keep consistent. Gravity pulls metal down and it runs ahead of the puddle. Reduce amperage 15 to 25 percent below flat, keep a small tight puddle, and travel steadily up without pausing, using short strokes that overlap about a third of the bead width.
• Vertical down is unusual and less controllable; most fabricators weld vertical up.
• Overhead inverts everything. The arc holds the metal in place and the rod is fed from below and slightly ahead. Keep the puddle small, keep amperage modest, expect more spatter, and use proper helmet and ventilation protection.

Coordination That Separates Good Welders From Great Ones

TIG demands four inputs at once: torch position and angle, arc length, amperage through the pedal, and filler rod timing. Each affects the others, and that feedback loop is the skill. The GTAW technique guidelines from Miller and the AWS resources at aws.org make the same point: the process rewards control rather than speed.

Practise on scrap of the same material and thickness as the real job, then vary one variable at a time and watch the puddle respond. Twenty minutes of that deliberate practice teaches more than an hour of repeating the same mistake, and it is how fabricators working to aerospace TIG standards are trained.

Get the preparation right and the rest of the process starts to feel intuitive. Get it wrong and you will fight the puddle no matter how good your technique is.

Metals, Applications, And Comparisons To Other Processes

Choosing a welding process is a trade-off between weld quality, deposition rate, portability, cost, and speed. TIG is often right, but plenty of shops reach for it when MIG or flux core would have moved them along twice as fast with almost no loss in quality.

Metals TIG Welding Handles Best

GTAW delivers a concentrated, tightly controlled arc with minimal filler and very little spatter, which makes it a favorite for thin gauge material and critical joints where distortion, undercut, or contamination would cause problems.

• Stainless steel: The classic GTAW application. It gives a smooth, oxide-free bead with excellent corrosion resistance, and grades like 304 and 316 are welded routinely in sanitary piping, food equipment, and architectural work.
• Aluminum and aluminum alloys: Often the go-to process for aluminum, where heat input must be controlled to avoid melting through thin sections. AC current, high-frequency starting, and the right filler rod make it standard for repair and manufacturing work. If you are new to the metal, aluminum MIG welding is a faster alternative worth comparing.
• Carbon and low-alloy steel: Entirely weldable, though most fabricators reach for stick or MIG on structural work. TIG earns its keep on thin sheet, tube, and stainless.
• Magnesium: TIG works well, but the metal burns easily and needs careful shielding and clean filler handling.
• Copper, brass, and nickel alloys: These high thermal conductivity metals suit TIG because the arc can dwell in a small, controlled pool without the base metal melting ahead of the puddle.

Preparation matters more than most people expect. The guide to prepping aluminum the right way is worth a read, because contamination is the number one reason TIG joints fail.

Where TIG Is Used in the Real World

Aerospace and defense. Aircraft and rocket components rely on GTAW because the process automates easily and the welds are repeatable, narrow, and spatter-free. Turbine components, exhaust parts, and structural frames are all common TIG work. The aerospace TIG welding guide covers the standards and training involved.

Food and beverage processing. Stainless hygienic tubing, tanks, and conveyor frames are TIG welded so the interior surface stays smooth and crevice-free, where bacteria could otherwise settle. Polished beads need no grinding, saving time and material.

Piping and pressure systems. Thin-wall stainless tubing in pharmaceutical, dairy, and chemical plants is routinely TIG welded, often with orbital equipment for consistency.

Automotive and transportation. Exhaust systems, alloy wheels, motorcycle frames, and aluminum body panels. Aluminum wheel repair is now a specialty service, covered in the alloy wheel welding guide.

Marine fabrication. Aluminum hulls and decks need TIG for the same reason aerospace does: light weight plus corrosion resistance. The aluminum boat welding guide covers strong hull joints.

Artistic and decorative work. Sculptors and furniture makers use TIG for puddle control, especially with thin decorative tubing and jewelry-scale work.

How TIG Compares To Other Processes

Each of the four common arc welding processes solves a different problem.

TIG versus MIG. TIG wins on control and finish quality. You can shape the puddle with the torch alone, and the arc is easier to center. MIG wins decisively on speed and thick sections. Continuous wire feed puts metal down far faster than hand-fed TIG rod, and newer aluminum flux welding options have narrowed the gap further. If you need a clean-looking aluminum part quickly, MIG may be smarter.

TIG versus stick. Stick is tougher in the field. It handles rust, paint, wind, and awkward positions, and the electrodes are cheap and easy to carry. TIG needs a clean, gas-shielded environment and more setup time. For a stainless railing in a factory versus one on a rooftop, the answer changes. The case for stick is laid out in why SMAW still wins.

TIG versus flux core. Flux core is built for structural steel in volume. It deposits quickly, works in wind, and tolerates rust better than MIG. TIG will always produce a prettier result, but on a bridge girder nobody is grading the bead. For aluminum, aluminum flux core welding has its own rules and gotchas worth knowing first.

Pick TIG when appearance matters, the material is thin, the joint is critical, or you are repairing in place. Pick MIG or flux core when you have volume, thick material, or time as the deciding factor. Pick stick when the environment is rough and the power is a generator. No process is universally best; knowing which suits the job in front of you is the real skill.

Benefits, Limitations, And Common Mistakes

Ask a fabricator why they reach for a TIG machine and the answer is always control. A non-consumable tungsten electrode and hand-fed filler rod put you in charge of where the heat goes and how much metal joins the joint. That control makes an excellent weld and a slower, costlier process than most alternatives.

Where GTAW Earns Its Reputation

• Exceptional cosmetic results. No spatter, no slag, a narrow smooth bead that often needs no grinding. On stainless, aluminum, and copper alloys, a well-run TIG bead is a finished surface.
• Unmatched heat control. The TIG torch and foot pedal let you raise and lower amperage continuously, controlling puddle size and melting rate.
• Works on nearly every weldable metal. Carbon steel, stainless, aluminum, magnesium, copper, nickel alloys, and titanium can all be TIG welded, which is why the process appears in aerospace TIG welding and in food, beverage, and pharmaceutical fabrication.
• Clean results in all positions. With no molten slag to fall off, out-of-position welds stay clean on the underside of the joint.
• Repeatable filler control. Small increments of filler metal go in second by second, which is how thin-gauge sheet and tube are welded without burn-through.

The Limitations Nobody Skips

GTAW has a lower deposition rate than consumable processes such as MIG, flux-cored wire, or stick welding. The electrode does not melt to become filler, so every gram of added metal is fed by hand. On a 10 mm plate that means multiple passes instead of one, and each extra pass adds time, heat input, distortion, and labour. That is usually why a fabricator reaches for aluminum flux core welding on a thick job.

Field work carries a similar trade-off. For thick plate, outdoor repairs, and awkward positions, stick welding still wins on speed and forgiveness: the coating does the cleaning and no foot pedal is needed. TIG wins on finish, thin material, and repeatability.

Skill is the other cost. A clean TIG weld means coordinating torch angle, filler rod placement, and amperage control at once. Beginners cannot manage all three, so the puddle grows, the arc wanders, and the bead suffers.

Equipment cost follows. A DC power source with high-frequency start, a proper torch, good regulator, correct tungsten, and decent filler rods cost more than a basic stick setup. Argon is not cheap, and out-of-position work burns shielding gas faster because you widen the nozzle.

Common Mistakes And Why They Happen

Two of these matter most on aluminum. Aluminum oxide forms in seconds and melts far above the base metal, so a TIG arc rolls over it unless it is removed. A dedicated aluminum cleaner for welding and a stainless brush on the freshly ground surface tell a sound weld from a porous one. Because aluminum conducts heat fast, too much amperage shows up as burn-through instead of penetration.

Shielding gas matters too. AWS C5.1 covers gas tungsten arc welding practice and sets out how shielding gas, electrode size, and technique relate to the joint. Most shops settle on argon flow in the mid-to-high teens of cubic feet per hour for general GTAW work, but follow the nozzle size, gas, and wire recommendations from the equipment manufacturer and check for leaks on every fresh cylinder.

None of this means TIG is a process to avoid. The quality ceiling is high, and so is the price of reaching it. AWS standards exist because the process must be controlled precisely, and welders who master it produce joints that look like finished product off the bench.

I’ll rewrite this section, tightening the prose while keeping every fact and link intact.

Safety, Codes, And Weld Quality

TIG earns its reputation for clean work, but “clean” describes the weld, not the shop. A GTAW arc is one of the most intense visible light sources you will ever stand in front of, the shielding gas that keeps the puddle pristine can quietly crowd the oxygen out of a small room, and a single bead of hot stainless running off a hull can find the one oily rag you left on the bench. Mature shops treat safety as part of the process rather than a set of rules stapled to the wall.

Arc Radiation: Protect Your Eyes and Skin

The arc in GTAW throws off intense ultraviolet and infrared radiation. Ultraviolet is the one that injures. Weld flash burn (arc eye) is a corneal injury that can happen in a single exposure, and it is not a normal sunburn, because arc UV can damage the cornea and retina without much heat reaching your skin. OSHA 1910.252 requires eye and face protection whenever you are in the arc zone or near a live arc, and calls for filter shades appropriate to the work. Industry guidance such as Miller’s GTAW guidelines reinforces the same point: proper PPE is the difference between a weld and an eye injury.

• Wear a helmet or auto-darkening hood with the correct filter shade for the amperage and material you are running, and never look at the arc directly.
• Safety glasses or goggles go under the hood, especially when tacking, positioning, or working with a partner holding the piece.
• Cover every inch of skin. Long sleeves, a leather jacket or apron, and gauntlet gloves are the standard. Arc UV burns on exposed skin often show up hours later, when you are home and the weld is long finished.
• Keep synthetics away from the arc. Nylon and polyester melt and can fuse to skin in seconds.

Electrical Safety

The GTAW circuit runs at high amperage through the torch, the work lead, and the clamp. OSHA 1910.252 covers grounding, electrode holders, and general electrical precautions, and the practical habits are easy to keep.

• Inspect the power lead, torch cable, work lead, and clamp before every job. Frayed insulation, a loose connector, or a scorched holder gets replaced, not taped.
• Keep cables and connections away from standing water and damp floors, and use ground-fault protection in wet or outdoor conditions.
• Never touch the tungsten, nozzle, or workpiece with a bare hand while the machine is energized, and never use the torch as a handhold for balance.
• Clean the clamp and make sure it bites bare metal. Paint, rust, and grease under the clamp cause arcing, erratic current, and stray voltage paths.
• Let the torch, nozzle, and filler rod cool before handling. A TIG nozzle runs hot enough to blister bare skin.

Shielding Gas Hazards, Fumes, And Ventilation

Argon and helium are inert, and both are heavier than air. That means a slow leak or a vented cylinder will collect in pits, in the bottom of a boat hull, and in any low point in the room. Oxygen displacement in a confined space can be fatal, and it will not announce itself the way a smoke alarm does. Never weld inside a tank, pit, or vessel without atmospheric testing, forced ventilation, an attendant, and a rescue plan, and never store cylinders in a confined space.

Cylinder handling deserves the same attention. Keep cylinders upright, chained or strapped, capped when not connected, and away from heat or sparks. A practical primer on gas selection and cylinder handling lives in the Air Gas welding supply guide on gases, cylinders, and safety.

Ventilation is where most of the long-term health risk lives. Fumes come from the base metal and from anything already on it: zinc from galvanized steel, chromium compounds from stainless, and organic vapors from paint, primer, and solvent. NIOSH’s welding fume resources note that welding fumes can cause lung damage, metal fume fever, and can aggravate heart conditions, and OSHA sets a permissible exposure limit for total welding fumes of 5 mg/m³. Good general ventilation plus local exhaust near the arc is the baseline, and confined spaces need additional precautions for atmospheric hazards.

The cheapest fume control happens before the arc is struck. Degrease the joint, remove rust and mill scale, and strip incompatible coatings. Getting the aluminum right is covered in our guide to cleaning aluminum properly before welding, and the same logic applies to galvanized or painted steel.

Fire Prevention

Hot metal, spatter, and slag are an ignition source in any shop. Keep combustibles at least 35 feet (11 m) away where practical, cover or protect nearby openings and surfaces, post a hot work permit where the site requires one, and keep a fire extinguisher within reach of the work area. A fire watch is standard during the job and for a period afterward, since slag can smolder inside a bundle of rags or a wood pallet long after the arc goes cold. Never leave a hot torch resting on a bench, and park cylinders on the opposite side of the work area from anything that burns.

Codes, Standards, And Weld Quality

Industrial TIG work is not run off memory and nerve. It runs off three documents: the Welding Procedure Specification (WPS), which states the recipe; the Procedure Qualification Record, which proves an operator or shop produced that recipe successfully; and the welder qualification, which proves the individual can do it. Codes define the variables those documents must cover: filler metal, preheat, interpass temperature, amperage, voltage, travel speed, shielding gas, joint design, and position.

For structural steel, AWS D1.1 governs; D1.6 covers stainless, D1.2 aluminum, and ASME BPVC Section IX handles pressure equipment. AWS publishes and maintains these documents through its standards program, and catalogs like ANSI’s listing of AWS C5.5M2003 show how the standards reach the shop floor as purchasable references. High-consequence industries tighten the requirements considerably, as you can see in our look at aerospace TIG welding standards and training, while marine fabrication lives under its own rule set covered in the AJ Marine welding guide on standards and safety practices.

Quality control then verifies the result. Every weld starts with visual inspection to the applicable acceptance criteria, and critical welds get non-destructive testing such as dye penetrant, magnetic particle, ultrasonic, or radiographic examination. Documentation matters as much as the bead: heat numbers, filler metal lot, gas cylinder, settings, operator, and inspection results all belong in the record. A code-compliant procedure still fails inspection if nobody documented that it was followed.

That is the honest balance of the process. GTAW gives you control, cleanliness, and a defensible quality record, and in exchange it asks for sharper PPE discipline, stricter gas and fume management, and paperwork that turns a good weld into a certified one.

Practical Tips, Troubleshooting, And Final Takeaways

Understanding the physics of TIG welding gets you only partway there. The gap between “I know how GTAW works” and “I can lay down a clean, repeatable bead” is closed by repetition, on scrap of the same alloy you plan to weld.

A Beginner-Friendly Workflow

1. Set up the machine and gas first. Connect the work lead directly to the workpiece, not a greasy vise or fixture. Purge the torch and set gas flow before striking an arc. Most shops run roughly 10 to 20 cubic feet per hour of argon for steel and stainless, with higher flows for aluminum and magnesium, where the reactive alloy demands heavier shielding. Setup details are covered in Miller’s GTAW guidelines.
2. Clean the joint aggressively. Remove oil, grease, paint, and oxide. Stainless and carbon steel need separate, dedicated brushes so you do not cross-contaminate. Aluminum is unforgiving, so treat it with a dedicated aluminum cleaner and stainless brush and work only with clean gloves.
3. Grind your tungsten and check the setup. A fresh, correctly ground point is the cheapest way to fix a wandering arc. Make sure the tungsten sticks out far enough to reach the work and the gas cup is not spattered shut.
4. Do not walk up to the work cold. Tack the joint, then practice travel speed and filler placement on a coupon of the same material and thickness. The metal responds to heat and filler the same way every time, so repeated practice on matching scrap is the most effective way to build puddle control.
5. Watch the puddle, not the arc. Keep your head positioned so you can see the pool, use short filler additions, and let the heat do the work rather than pushing the rod into the arc.

Troubleshooting: A Quick Reference

Building Skill Over Time

Welding proficiency comes from hundreds of small repetitions, so build a practice plan you will actually keep. Cut coupons from the same alloy and thickness you work with, weld them with the same filler and gas, and keep every one. Comparing them side by side teaches you more than any tutorial, because you can watch your own travel speed improve.

Once the basics feel automatic, move to demanding work. Thin stainless in all positions, aluminum with AC and a foot pedal, or pressure-retaining pipe will each expose habits the flat position hides. Guidance written for aerospace TIG welding standards, where welds are fully certified and inspected, makes an excellent stretch goal. If this is turning into a career, aerospace welding schools and formal training through the American Welding Society give you structured feedback that practice alone cannot. And remember, OSHA welding safety rules and proper fume control matter as much as technique.

The Short Answer

So, how does TIG welding work? A non-consumable tungsten electrode forms an arc with the workpiece, and a stream of shielding gas such as argon surrounds the arc, protecting the hot molten metal from the air. The arc’s heat melts the base material, and the puddle of molten metal cools into a solid joint. Everything else, amperage, arc length, travel speed, filler addition, is simply you controlling how that puddle forms and solidifies.

Master the puddle and everything else follows. Study the fundamentals, practice on scrap of the same alloy, learn to read your own welds, and keep refining the TIG process one bead at a time.

Frequently Asked Questions

What does TIG stand for in welding?

TIG stands for Tungsten Inert Gas welding. The more technical name for this process is Gas Tungsten Arc Welding, or GTAW.

Is TIG welding harder to learn than MIG welding?

For most beginners, TIG welding is more difficult to learn than MIG due to the need to simultaneously control the torch, amperage, and filler rod with both hands and a foot pedal. However, with practice it grants far more control over the weld.

What shielding gas is used for TIG welding?

Pure argon is the most common shielding gas for TIG welding. For some applications, argon-helium mixtures may be used to increase heat input and travel speed on thicker sections of certain metals.

Can you TIG weld without filler metal?

Yes. This is called an autogenous weld, and it is commonly used for thin materials or edge joints where the base metal itself is melted and fused together without adding a filler rod.

Why does aluminum need AC for TIG welding?

Aluminum forms a tenacious oxide layer that melts at a much higher temperature than the base metal. Alternating Current (AC) provides a cleaning action during the electrode positive portion of the cycle to break up this oxide whilst still providing heat to melt the aluminum.

What causes a black or discolored TIG weld on stainless steel?

Discoloration is typically caused by oxidation from insufficient shielding gas coverage or heat tint from excessive heat input. Proper gas coverage, clean prep, and controlled amperage greatly reduce this occurrence.

Is TIG welding safe indoors?

TIG welding can be performed indoors, however adequate ventilation is required to mitigate welding fumes. In confined spaces, additional atmospheric testing and precautions are necessary due to the risk of shielding gas displacing oxygen.

Why does my tungsten ball up or contaminate?

Tungsten can become contaminated from touching the molten puddle, using incorrect polarity, inadequate shielding, or grinding contamination onto the electrode. Using the correct tungsten type for AC or DC as well as proper technique will help prevent this.

What metals can be TIG welded?

TIG welding can be used on a wide variety of metals including carbon steel, stainless steel, aluminum, magnesium, nickel alloys, copper, and titanium. Proper cleaning, gas selection, and parameters are crucial for each alloy.

How fast is TIG welding compared to MIG welding?

TIG welding is generally much slower than MIG welding due to its manual filler addition and focus on precision. Whilst this limits production speed, it is often preferred for quality critical, intricate, or thin walled welds.