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TIG Welding Process and Tips

TIG welding is used on a greater variety of metals than MIG welding and requires more instruction and practice. The TIG process is used for welding steel, stainless steel, chromalloy, aluminum, nickel alloys, magnesium, copper, brass, bronze, and even gold. It is great for home projects, construction, repair, or even automotive welding.

TIG welding creates a high quality, clean weld, which makes it ideal when appearance and durability count. Below are some tips from TIG welding experts for beginners and experienced welders hoping to improve their technique.

A Clean Joint and Clean Tungsten

While a weld will be stronger if the joint is properly cleaned with a grinder and sand paper if necessary, in TIG welding it's essential to keep the tungsten clean as well. One careless moment can contaminate the tungsten. Be careful to avoid touching the end of it with a finger or even a glove, as finger oils or residue on a glove can both wreck the tip of the tungsten that will be used for welding.

Thin Gloves

Since TIG welding requires a rapid and steady feeding of filler wire, use a thin glove that will make it easy to keep the filler wire constantly supplied to the weld pool. There are specially made TIG gloves made of goat skin or woven cotton that will make it much easier to feed the filler wire.

Filler Rod Size

There are plenty of things that can go wrong with TIG welding, but one of the most important things to get right is choosing a filler rod that matches the metal being welded. A general rule of thumb is to use a thin rod on thin metal and a thick rod on thick metal. However, sometimes welding problems can be solved by changing the thickness of the metal rod.

Torch Angle

Another source of welding problems can be an incorrect torch angle. For TIG welding the torch angle should only be about 10 degrees or less. Welders want a neat, consistent weld bead by the time their done, not an uneven weld with peaks and valleys that results from melting the filler rod before it reaches the puddle. Too much angle exposes the rod to excessive heat and melts it too fast, leading to uneven and unsightly welds.

Avoid Radioactive Electrodes

The 2% thoriated tungsten electrodes can be dangerous to use because they are radioactive. The last thing most welders want is to grind a thoriated electrode and spray themselves with radioactive particles. As it turns out, 2% lanthanated electrodes (color-coded gold) are generally just as good as the thoriated electrodes and are sometimes preferable for certain jobs.

Use the Smallest Electrode Possible

Besides choosing the right filler metal size, it's also important to pick the correct electrode size for TIG welding. Generally speaking, use the smallest electrode possible, though keep in mind that all electrode usage guides are not necessarily hard and fast rules. There are advantages and trade offs. Larger electrodes last longer but are difficult to start and may make it difficult to control the arc, while smaller electrodes run the risk of melting if used with too much electrical current.

Torch Position

While TIG welding, the tungsten in the torch cannot touch the material. If it does, it needs to be ground again. The torch should be held at a 70 to 80 degree angle in relation to the piece being welded with the tungsten about 1/8 to 1/4 of an inch off the surface. Always use a push technique with the TIG torch.

Shielding Gas

TIG welding uses a shielding gas, usually argon, to prevent air from contaminating the weld. Naturally, avoid TIG welding outside when there is a breeze that can shift the gas away from the weld pool. In addition, it's critical to properly regulate the gas flow, as too little gas won't protect the weld pool, but too much can lead to the same result.

Foot Pedal Control

The foot pedal for TIG welding is a way to regulate the amount of heat, which will impact the rate at which the filler metal is melted. Too much heat will melt the filler too quickly and lead to a sloppy, uneven weld. The heat should be controlled so that the weld pool is consistently 1/4 inch wide.

Filler Metal Angle

The filler metal should be added at a steady, consistent rate and held at a 15 degree angle in relation to the work piece. As the work piece is heated up, the filler should be added to the puddle of metal quickly and gently so that an even weld can form.

Butt Welds

When welding a butt joint, center the weld pool on the adjoining edges. When finishing, decrease the heat (amperage) to aid in filling the crater.

How to Weld Lap Joints

For a lap weld, form the weld pool so that the edge of the overlapping piece and the flat surface of the second piece flow together. Since the edge will melt faster, dip the filler rod next to the edge and make sure you are using enough filler metal to complete the joint.

How to Weld a T-Joint

When welding a T-joint, an edge and a flat surface are joined together, and then the edge will melt faster. Angle the torch to direct more heat to the flat surface and extend the electrode beyond the cup to hold a shorter arc. Deposit the filler rod where the edge is melting.

How to Weld a Corner joint

For a corner joint, both edges of the adjoining pieces should be melted and the weld pool should be kept on the joint centerline. A convex bead is necessary for this joint, so a sufficient amount of filler metal is needed.

Improve Arc Starting

Keep the torch and work leads as short as possible and move the power source as close as possible to the work so that the torch cable is prevented from contacting any grounded metal. Before starting, check and tighten all connections.

Matching Metal with Tungsten

For projects that involve welding aluminum, use AC current and a ceriated (orange identifying band) or 1.5% lanthanated (gold identifying band) tungsten. When welding steel and stainless steel, use DC-Straight Polarity (DCEN) and a 2% thoriated (red identifying band) tungsten or replace with a lanthanated electrode as mentioned above.

Choosing the Right Tungsten

The use of pure tungsten is decreasing since it melts at a lower temperature and forms a ball at the tip that interferes with weld poll visibility and leads to instability of the welding arc. Welders today prefer ceriated tungsten that can withstand higher temperatures and works very well with the new square wave and inverter machines. It starts well at low amperages and works on both AC and DC polarities. When welding aluminum, it is common to grind a point on ceriated tungsten (especially when welding on thinner materials), though that point is often flattened so that it isn't a sharp point.