TIG welding has become popular among DIYers, at-home mechanics, and construction professionals because it can be used with all types of metals. You can join steel, aluminum, copper, and stainless steel in a wide range of thicknesses with the TIG welding process. Of the various arc welding processes, TIG offers the highest quality of weldment.
The welds are precise and neat. The work is clean and does not generate smoke or residue. The absence of slag reduces the chance of welding defects -- like slag inclusions which may result in poor weld metal. Unlike conventional arc welding, the finished weld requires virtually no cleaning.
Having seen all the benefits of TIG welding, in this TIG guide, we'll see what the process is, how it works, what supplies are needed, and how the process is carried out, as well as the industries the welding technique is used in and the main pros and cons.
Jump To A Section:
- What Is TIG Welding?
- The Science Behind TIG Welding
- What Supplies Do You Need to TIG Weld?
- Getting Started With a TIG Welder
- TIG Welding Applications
- TIG Welding Pros and Cons
- TIG Welding FAQ
- Next Steps: What to Do After Learning TIG Welding
What Is TIG Welding?
According to The Welding Institute (TWI), TIG welding is a fusion welding process that uses a nonconsumable (tungsten) electrode to heat the workpiece. It then protects the welds with inert gas.
What Does TIG Mean?
TIG simply means tungsten inert gas welding. The welding process is also alternatively referred to as gas tungsten arc welding (GTAW).
What this means is, during TIG welding, an electric arc is generated between a tungsten electrode and the workpiece. The electric arc is intense but can be guided excellently.
The Science Behind TIG Welding
TIG welding is based on raising the temperature of the parts to be assembled up to a melting point by the electric arc which is constructed between the nonconsumable tungsten electrode and workpiece due to the passage of an alternating or direct electric current.
Welding is most often carried out in direct polarity (pole (-) of the generator connected to the electrode) for metals and alloys (like steel, stainless steel, copper, titanium, and nickel). However, in the case of light alloys of aluminum or magnesium, we weld in alternating polarity to have a self-cleaning process -- which is the breakdown of the oxide layer formed during welding. Breakdown of this layer occurs by reversing polarities using AC current.
It is not possible to weld in reverse polarity (pole (+) connected to the electrode) because this would destroy the electrode by melting it as most arc heat, in this case, will be concentrated on the tungsten electrode tip.
TIG welding machines are equipped with a transformer or modern inverter technology. Modern inverter technology welders are not only much lighter than transformers, they also allow significantly more settings that you can use for welding.
More sophisticated devices offer the option of TIG pulse welding in which you can adapt individual values even more precisely to your requirements during welding.
The pulse function reduces the effect of heat on the material, and enables the welding of very thin sheets. In addition to the pulse frequency or the number of pulses per second, you can use regulators to directly influence current values such as the base current, the peak current, time of pulse on base current and peak current, and other factors, to achieve the most perfect weld seam possible by precise control of arc produced heat input.
How Does TIG Welding Work?
The TIG process consists of establishing an electric arc between a nonfusible electrode (tungsten) and the part to be welded. With this process, it is possible to weld with or without filler metal. This filler metal is often the same material as the part to be welded.
TIG welding requires the supply of an inert shielding gas such as pure argon. During TIG welding, the necessary current is delivered by the tungsten electrode -- the centerpiece of the welding process. This tungsten electrode is the source of the electric arc which heats and liquefies the material to be welded.
During this time, the shielding gas escapes from the gas nozzle. Then it protects the heated material (as well as the liquid molten pool) against chemical reactions in contact with ambient air. This process guarantees high-quality weld seams.
The electric arc allows the temperature to be raised to more than 6,000 degrees Fahrenheit.
What Supplies Do You Need to TIG Weld?
Some of the tools and materials needed for TIG welding follow.
In contrast to welding with MIG-MAG processes where the consumable filler material also acts as a welding electrode, a tungsten electrode is used in TIG welding. This electrode conducts the current and its shape influences the weld seam. In addition, it does not melt and has a longer shelf life. The behavior of the weld pool can also be influenced by the chemical composition.
The electrodes used consist mainly of tungsten at more than 99 percent. Metal oxides are added to increase the electronic emissivity of the electrode and the efficiency. Therefore, there are many types of tungsten electrodes based on oxides present with tungsten, and every type has a color code (like red color for W-Tho2) that contains thorium oxide and green color for pure tungsten electrodes. For welding aluminum, there are also electrodes made of pure tungsten.
The tungsten electrode is enveloped by a gas nozzle through which the inert gas (e.g., argon, helium, hydrogen, or a mixture of these) flows. It thus shields the arc and weld metal from oxidation from the surrounding atmosphere.
The TIG welding equipment comprises a constant current CC power source, an earth cable, a welding torch, and a TIG welding gas container or a gas network connection. The welding machine is essential in this kit. The welding machine can be a transformer or inverter technology type. The machine can also contain a liquid cooling unit. A wire feeder is not required as the filler metal is fed in manually.
The power used in welding machines is usually a constant current power source which may produce an alternating current AC, a direct current positive DC+ or direct current negative DC- (abbreviated as AC/DC power source). The most common TIG welders use direct current (DC).
When TIG welding steel, or stainless steel, the DC TIG welding process shows good results. If you want to start TIG welding aluminum, you have to use alternating current since TIG welding aluminum requires special welding requirements regarding the self-cleaning process mentioned before.
To do this, you can use AC DC TIG welding machines -- which are also often called aluminum welding machines. When TIG welding aluminum with an alternating current, hard oxide layers must not form on the aluminum. These layers can cause the weld seam to become inferior. With the AC TIG welding method, other light metals such as magnesium can also be welded quite efficiently.
Torch or Electrode Holder
The TIG welding torch or electrode holder is the manual part of the welding machine. This ensures you can carry out precise welding work directly on the workpiece.
The TIG welding torch usually holds a tungsten electrode stabilized by a clamping sleeve with the help of which, the arc is generated. A torch cap protects the welder from contact with the end of the nonconsumable tungsten electrode.
A shielding gas line leads through the handle of the TIG welding torch to the gas nozzle and conveys the required shielding gas.
In the case of a water-cooled TIG welding torch (when welding current exceeds 250 AMP), two additional lines run through the handle of the torch, namely the water inlet, and the return. They ensure adequate cooling of the burner and protect against overheating.
Finally, of course, the welding current lead also runs through the handle of the TIG welding torch to the tungsten electrode to generate the required welding circuit.
With the help of the torch switch on the handle of the TIG welding torch, you can switch the welding torch on and off and thus start and stop the flow of electricity, shielding gas, and cooling water.
At the start of the arc, a high-frequency current is used to ease the arc ignition. In the case of switching off the current, the switch in the handle allows the current to be lowered gradually until switch off. Gradual lowering decreases the crater cracks which are produced in traditional welding processes due to the sudden switch-off of current at the end of welding.
Shielding Gas Supply (Helium, Argon, Hydrogen, or Mixture)
In most cases, the gas used is argon, especially in Europe. Germany, Belgium, and the Netherlands have some of the largest reserves of argon gas and are top exporters according to the Observatory of Economic Complexity (OEC).
This neutral gas makes it possible to avoid instant oxidation during the melting of the welded metal. It also influences the creation of the arc on the ignition, the shape of the bead, and the welding speed.
Argon is better for thinner metals due to lower heat requirements. In the United States, helium is used as helium is more abundant here. Although it makes ignition more difficult, helium raises the arc voltage and therefore, allows greater penetration and welding speed.
Purge gas (argon) can be mixed with hydrogen (5 or 10%) to obtain two distinct results which depend on the desired goal.
When you want to reduce the heat-affected zone (HAZ), the addition of hydrogen makes it possible to reduce the amount of energy required by about 25 percent. This is because hydrogen has the property of concentrating the electron beam emanating from the tungsten and thus reducing the width of the weld bead.
For austenitic stainless steels, the use of argon + hydrogen mixtures improve productivity by increasing penetration and welding speeds.
Filler Metal Rod
The filler metal consists of a rod of variable diameter; the composition of which is similar to the metal being welded. As its name suggests, this metal fuses with the arc and constitutes an addition of material during the formation of the weld bead. Here’s a list of the most widely used filler metals.
- ER5356 or S Al 5356 for aluminum
- ER316L or W 19 12 3 L for austenitic stainless steels
- ER70S-3 or W 42 5 W3Si1 for common carbon steels
- TA6V for titanium
The use of gas, welding rays, and weld spatters can be dangerous for the welder. The use of safety gear is important.
Safety goggles are used for protecting the eyes from dangerous rays and sparks. Welding without these can expose you to flash burns or what is called the welder's eye which is the feeling of having sand in the eyes and symptoms such as eye tearing and reddening, sensitivity to light, and more.
Long Sleeve Shirts and Pants
You will need long sleeve shirts and pants to protect your body from welding spatters, and the welding clothes must also be flame retardant (FR).
Leather boots are part of the safety gear. They protect the welder from sparks, electrocution, and other welding hazards.
Again, good TIG welding gloves are flame retardant. Fire retardancy ensures they can withstand high heat. The welding gloves must protect the welder from flame, cuts, sparks, and heat.
The welder's sunscreen should be treated with zinc oxide to physically block all forms of radiation emitted from welding activities. These can be UVA, UVB, or UVC.
Getting Started With a TIG Welder
Welding with tungsten inert gas involves the following procedures.
Prepare Your Tools and Workspace
Before starting your welding machine, be sure to put on protective goggles, heavy, fire-resistant welding clothes, and a welding mask with eye protection.
Also, make sure you have a clean surface. The preparation of a carbon steel part consists of stripping it bare with the use of a grinding wheel or sandblaster. For an aluminum part, it is best to use a stainless steel wire brush.
If the part is stainless steel, wipe the weld area with a solvent-soaked rag. Before starting to weld, be sure to store the rag and chemicals in a safe place.
Pick and Grind the Electrode
The size of the tungsten electrode depends on the thickness of the workpiece and the welding current. Be sure to grind the electrode radially around the circumference and not directly toward the ends.
You can use a pumice stone for sharpening. To be on the safe side, work to orient the electrode in the same direction as the stone's movement.
Have a rounded end if welding is done with alternating current, or a sharp end if welding current is direct current. If you are doing a fillet weld or butt weld, sharpen the electrode to get a rod 5 to 6 millimeters long.
Insert the Electrode Into the Collet
Unscrew the rear part of the electrode holder and insert the electrode. Then screw this part back. Usually, the electrode should protrude about 6 mm outside the protective sheath of the clamp.
Choose a Shielding Gas and Adjust the Welding Gas Flow
You can use pure argon, helium, or a mix of argon and helium. Remove the protective plastic cap. Bleed the threaded body of the valve by opening and closing it quickly to remove foreign matter.
Tighten the regulator screw. Fully tighten the nut by turning the regulator to position it properly in the valve. Tighten the regulator with a wrench, making sure to turn the pressure knob counterclockwise.
Connect the gas hose and the flow meter, then open the tank valve. Be sure to turn on the tap slowly and gradually. A quarter turn is usually sufficient.
Finally, check that there is no gas leak, either by ear or by spraying a leak detector product on the fittings. Adjust the gas flow by acting on the regulator. The setting depends on the nature of the welding, but it is usually between 4 and 12 liters per minute.
Arrange the Welding Station
Connect the pedal to the welding station. This pedal is used to control the temperature during welding. Assemble the TIG welding torch. Torches of this type are equipped with a ceramic nozzle to orient the argon, a copper sleeve to hold the electrode, and a cooling medium. Secure the torch using the adapter provided in your accessory kit.
Select the Polarity
You can adjust the polarity of your station according to the nature of the metal you are going to weld. If there are aluminum parts, set the selector to the position that corresponds to alternating current (AC). On the other hand, if the parts to be welded are made of steel, choose the assembly in direct polarity, that is to say in direct current-negative electrode.
Adjust the Intensity of the Current
The intensity adjustment allows you to control the welding process. The greater the thickness of the parts to be welded, the higher the intensity will be. But if you coordinate your action on the pedal correctly, you will have fewer problems with intensity.
Here are some common values of amperage as a function of thickness: 1.6 mm, 30 to 120 amps; 2.4 mm, 80 to 240 amps; 3.2 mm, 200 to 380 amps.
Weld the Base Metals
Continue by putting the pieces together. Secure these parts using an angle iron or flat bar with hose clamps. Point the pieces together (making welding points intended to hold the parts together until the welding is complete). Place these points a few inches from each other along the weld joint.
Register the Beads
Hold the TIG torch in your hand. Be sure to keep it at an angle of about 75 degrees, with the electrode within 0.5 cm of the parts to be welded. Avoid touching the parts with the tungsten electrode to avoid contaminating the weld.
Control the welding temperature using the foot control. The width of the weld pool should be approximately 0.5 cm. It is important to keep the pool at a reasonable size to avoid badly finishing the welding operation.
Hold the lead electrode in the other hand. Hold it at the point where the metal will be heated by the torch so that it makes a 15-degree angle with the horizontal.
Heat the base metal with the torch. Under the effect of heat, a weld pool will be created and will be used to weld the two parts. Once the weld puddle touches the two pieces, fill the joint with the filler metal by having a rapid movement to avoid forming bulges. The filler metal will strengthen the weld bead.
Extend the Weld Pool
To do this, move the electric arc in the right direction. Unlike the MIG welding process, where you move the weld pool in the direction of torch movement, in the TIG process, you push the weld pool in the opposite direction of the tilt of the torch.
Have a hand movement similar to that of a left-handed person holding a pencil. While a right-hander moves his pencil as if to make an MIG weld (with both angles tilted to the right), a left-hander holds his pencil tilted to the left -- although he must push it to the right. Finish your weld by advancing the weld pool. You have just made a TIG weld!
The following YouTube tutorial by Miller Welders offers more TIG welding tips and TIG welding techniques for those who want to learn more: https://youtu.be/tNYmo2_DI6c
TIG Welding Applications
What is TIG welding used for?
Aerospace and Aircraft Construction
TIG welding is highly used in aerospace and aircraft applications as the process ensures a strong and clean weld joint. This is perfect for repairing and assembling aircraft components.
The TIG process is known to help reduce corrosion. Vehicle fenders are TIG welded to prevent rust.
Auto Body Repairs
TIG welding is ideal for auto body work. It is a process that is highly used in auto body restoration and repairs.
The orbital TIG welding process is often considered the best welding process for pipeline assemblies for welding complete joints for small bore pipes that are not exceeding 2 ½ inches in diameter, or for welding the root passes while filling and cap passes are done by using other welding processes: shielded metal arc welding (SMAW), metal inert gas and metal active gas (MIG-MAG), and flux-cored arc welding (FCAW) processes are also used.
TIG Welding Pros and Cons
Some of the advantages and downsides of TIG welding are listed below.
- Very clean welds
- Can be used with or without filler material
- It creates strong welds
- Offers a high degree of control to the welder
- Can be done in manual or automatic methods
- Time consuming
- Cannot be used for thicker metal joints
- Needs highly skilled welders
TIG Welding FAQ
Why Is TIG Welding so Popular?
TIG welding is quite popular because it produces higher quality welds than MIG welding offers. Also, it's more precise and can be used with all types of metals. You can join steel, aluminum, copper, and stainless steel with the TIG welding process in a wide range of thicknesses.
What Is the Difference Between TIG and MIG Welding?
During MIG-MAG welding, the filler metal is introduced through the torch, which is why TIG torches are different from MIG-MAG torches. TIG welding doesn't require this method.
What Material Is TIG Welding Suitable For?
TIG welding is suitable in particular for stainless steel, aluminum, and nickel alloys -- from very thin aluminum and stainless steel sheets to special materials such as titanium.
Does TIG Welding Require Filler Metal?
In principle, no filler metal is required for TIG welding. The assembly by welding is carried out here by fusing the joint and in this case, it is called autogenous welding. If it becomes necessary to work with filler metal, this must be added manually to the weld pool either by hand or using a special cold wire feeder. With TIG welding, the torch is guided, and the filler metal is fed either dropwise or continuously -- constantly keeping the filler wire in the weld pool.
Next Steps: What to Do After Learning TIG Welding
After getting to know the basics of TIG welding, you have to keep learning.
There are YouTube courses that teach you all the basics, techniques, and technology used in TIG welding, as well as the step-by-step to complete each project.
Trade Career Certification
It takes around 40 hours to learn TIG welding. And when you're done, it's time to start seeking certification. Trade career certifications in this field include the CW, CWS, CRWT, CWE, and CWI.
You can also find TIG welding crash courses online. The workshops are often offered for tuition, but everything needed is supposed to be supplied.