In short: TIG welding joins metal with an arc held between the workpiece and a tungsten electrode that is never consumed, under a shield of inert gas, with filler metal added separately by hand or left out altogether. Its formal name is gas tungsten arc welding, or GTAW.
That one sentence hides the reason the process exists. Because the electrode is not consumed and the filler is not attached to the torch, heat and filler are two separate controls, and the welder sets each one independently while the bead is forming. Everything TIG is good at, and everything it costs, follows from that.
The Arc, the Tungsten and the Gas
The tungsten carries the arc and nothing else. It melts at a higher temperature than the metal being welded, so it survives the arc rather than being fed into the joint, which is why the electrode is called non-consumable.
Around that arc sits a shield of argon, sometimes mixed with helium. Air is the problem it solves. Molten steel, and stainless and aluminum far more so, pick up oxygen and nitrogen the moment they are exposed, and the result is a weld full of gas pockets and oxide. The gas flowing out of the cup pushes air away from the pool until it has frozen and cooled enough to stop reacting.
The filler rod, when one is used, is dipped into the leading edge of the pool by hand. On thin joints and on tight-fitting edges it is often left out entirely and the two parent edges are simply fused together, which is called an autogenous weld.
Heat is usually controlled with a foot pedal or a thumb control on the torch, rather than being fixed before the arc is struck. That matters more than it sounds: a setting that is right at the start of a seam is too hot by the end, because the part has been heating up the whole time.
What You Need to Run It
The kit is short. A power source that can strike and hold a stable low-current arc, a torch with a collet and a ceramic cup, tungsten electrodes, a cylinder of argon with a regulator, and filler rod in the alloy you are joining.
Polarity decides half of what the machine can weld. Steel, stainless and titanium go on direct current, while aluminum needs alternating current so the arc can break up the tough oxide skin that forms on it. How the arc is started decides much of the rest. High-frequency starting lets the arc jump the gap without the tungsten ever touching the work, which keeps the electrode clean; scratch starting, the alternative, does not.
What It Is Good At
TIG suits work where the seam is seen, measured, or has to hold pressure.
Thin sheet is the clearest case. With the heat under a pedal and no wire being pushed into the joint, a skilled welder can put a bead on material thin enough that most other arc processes would blow through it.
Stainless, aluminum, titanium, copper and nickel alloys are all commonly TIG welded, which is a wider materials list than most processes manage from one machine. Pipe and tube work relies on it for root passes, because the welder can see and control the underside of the pool. Repair and one-off fabrication favor it for the same reason.
The finish is the other draw. A TIG bead usually needs no grinding before a part ships, so on visible stainless the process saves work downstream rather than at the arc.
Where TIG Costs You
Speed first. Deposition is low by design, and every filler addition is a separate hand movement. On long seams and heavy sections that is the dominant cost, which is why production shops reach for other processes there. The comparison is set out in MIG and TIG side by side and, against a beam, in laser welding versus TIG.
Preparation is the cost people underestimate. TIG shows contamination that other processes bury. Oil, paint, cutting fluid, marker ink and mill scale all come back as porosity or a dirty, sluggish pool, so cleaning the joint belongs to the job itself, not to whatever minutes are left before it. On aluminum the oxide layer needs its own treatment, covered in cleaning aluminum before welding.
A contaminated tungsten cannot be fixed with settings. Touch the electrode to the pool or the filler rod and the arc immediately goes wide and starts wandering. No amount of current adjustment brings it back; the electrode has to be pulled and reground. When it is reground, the grinding marks must run along the electrode, not across it, because marks across the tip steer the arc off center.
A stainless root can look perfect from the top and be ruined underneath. Weld stainless pipe without purging the inside with argon and the back of the root oxidizes into a rough, gray, crumbly surface. The face of the weld gives no hint. It is found later, at inspection or in service.
The part heats up and the settings do not. Anyone watching a long seam will see the bead widen toward the end as the base metal soaks up heat. That is what the pedal is for, and it is also why a procedure qualified on a cold coupon does not always transfer to a hot production part.
TIG quality lives in the operator’s hand. If the same seam has to come out identical a thousand times over, that dependency is the thing worth designing out, and there are only three ways to do it: better fixturing, a tighter procedure, or a different process. If the third one is on the table, what an operator notices first is the weight in the hand: the handheld laser welders carry a 0.5 kg gun, with 10 m of fiber standard on the 2 kW and 3 kW machines, and among the laser welding machines the 3 kW units need a 380 V three-phase supply while the rest stay on 220 V. Tell us about the seam and the tolerance it must hold; we will say which of the three is the cheap fix. Ask Topstar
Common Questions
What does TIG stand for?
Tungsten inert gas. The formal name is gas tungsten arc welding, GTAW, and the two terms mean the same process.
Can you TIG weld without filler rod?
Yes. When the edges fit tightly and no reinforcement is needed, the parent metal is fused on its own, which is called an autogenous weld and is common on thin sheet and on tube.
Why does my TIG weld turn black?
Almost always shielding. Check the gas is flowing, the cup is not cracked, the flow rate suits the cup size, and that you are holding the torch over the weld until post-flow ends rather than pulling it away the moment the arc stops.
Is TIG hard to learn?
Harder than most arc processes, because two hands and a foot each do something different at the same time. Expect to spend real bench time on scrap before a stainless seam looks like the ones in photographs.
Where does laser welding fit next to it?
It is a different machine class with a different skill curve, covered in what laser welding is and in the laser welding guide.
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Get in touch
- Ask Topstar about a seam you are welding by hand and how many of them you run.
