TIG welding: description, information and equipment

Not sure which welding method to choose? The following article will help you understand the basics of TIG welding. Find out what the most important parameters are, how to choose the right equipment and also read the most common mistakes made by welders. We will also try to answer the following question: when is TIG welding used?

TIG welding parameters

This method uses a non-consumable tungsten electrode, shielded by inert gases (most often argon and helium) or their mixtures. Tungsten, both in its pure or enriched with oxides, is used for the production of electrodes. Color markings indicate chemical composition:

• Green: from pure tungsten
• Grey: with added cerium oxide (ceriate)
• White: with added zirconium oxide (zirconized)
• Gold: with added lanthanum oxide (lanthanide)
• Red: with added thorium oxide (thoriated)

The electrodes also have different diameters. The thinnest rods are 1 mm thick and the thickest 6.4 mm.

The arc strikes between the electrode and the processed material. During the arc welding process, the shielding gas cools the electrode and protects the weld pool from atmospheric gases. Since no flux is used, the joining process does not generate any significant changes in the chemical composition of the materials. There is no splashing either.

The most important parameters of TIG welding are:

• Type and intensity of current: Both direct and alternating current can be used for this method. If direct current is chosen, the process can have a negative or positive polarity. The electrode connected to the positive pole causes a strong heating of the tip, which forces the permitted current intensity to decrease. If you want to achieve high intensity, you need to use an electrode with a larger diameter. Welding with alternating current does not involve such restrictions, but can reduce the quality of the weld. The intensity of the current determines the depth of fusion and the width of the weld. It usually has a range of 5 to 600 Amperes.
• Arc voltage: It is responsible for its length and also the shape of the weld, depending on the gas used. Its value is linked to the electrode material and the chosen current intensity.
• Welding speed: This is the speed of the electrode with a glowing arc. It covers a range from 0.05 to 0.4 m/min. This influences the depth of fusion and the width of the weld, in a similar way to the current intensity. This depends not only on the experience of the welder and the welding position but also on the thickness and type of material and the intensity of the current.
• Type and flow rate of shielding gas: We have already mentioned how important shielding gas is at the beginning of this article. Many manuals suggest that it is better to use argon 4.0 or its types with even higher purity than 4.5 and 5.0. These are very high-quality gases. Under neutral conditions, the flow is usually 6-15 or 5-20 l/min. To ensure both quality and safety when working with gas, it is necessary to use an appropriately shaped nozzle. If you want to regulate the gas flow (very precisely), you need to use a regulator equipped with a flow meter.
• Diameter and type of non-consumable electrode: The types of electrodes mentioned at the beginning of this article should be selected based on the material. It is therefore necessary to remember the type of current, its polarity and its intensity. The parameters are adequately covered in publications such as the TIG welding manual, a welding guide etc, available on the website.
• Balance and frequency of alternating current: These parameters are typical of alternating current TIG welding. The frequency is 60-200 Hz (80-120 Hz is often recommended as the optimal range). AC current balance is of particular importance when working with aluminium, which is difficult to weld. This has an impact on the heat distribution between the processed material and the electrode.

A welder with many years of professional experience will intuitively know how to set the current. But what happens if you don't have enough experience and find it difficult to estimate the appropriate value? By using the trial and error method, you might just waste a lot of material. In these situations, correlation graphs will definitely be useful. They help you choose the right current and electrode, depending on what you are welding. For example: mild steel with a thickness of 2-3 mm requires an intensity of 60-70 A and the use of an electrode with a diameter of 2 mm. You can easily find these tables by consulting the websites here, electrode manufacturer websites, and technician manuals. For beginners, we recommend welding machines with smooth current regulation.

TIG welding joints

The TIG method allows for clean, high-quality welds, which is considered by many welders one of the main advantages. However, no matter how careful you are and what connection method you use, the following types are generally used:

• Head joint: It is created between the wall that forms the thickness of one element with the same wall of the other element. There are two types: complete penetration to cover the entire thickness and partial penetration to cover only part of it.
• Thread joint: This forms in the groove between the two unbeveled sides of the weld. Beveling is a cutting method in which the edge is not perpendicular to the top of the machined material.
• Edge join: This is a type of welding that covers the entire thickness of the sheet metal or a part of it. It consists of folding and fusing its edges without using a binder. It is suitable for metal sheets with a maximum thickness of 3 mm.
• Joint for holes: One of the connected elements must have an oblong or circular hole to be filled with a binder.
• Stitched joint: This welding does not require the presence of a hole. One of the sheets melts and then blends with the other beneath it.

Errori comuni nella saldatura TIG

Novice welders can make many mistakes. This is perfectly normal and takes some time to learn it. Below is a list of the most common errors:

• Unstable binder application: If the binder is applied in this way, its layer may form incorrectly. If the welding process is interrupted (e.g. the binder comes into contact with the electrode), it can be restarted. However, the wet piece of the electrode must be smoothed so that the tungsten does not enter the weld. It will then be cleaned without any additional external elements.
• Incorrect technique of using the torch: Don't swing too wide. Move the flashlight vigorously forward and hold it at a sharp angle.
• Lack of protection of a liquid solder: If you decide to take a short break, remember to leave the liquid solder protected. It needs time to cool down. You can continue working later.
• Incorrect resumption of welding: After the pause, you must immediately apply the binder, dissolve a bath and apply more material.

If you make these mistakes, your weld will be uneven and the sheet metal will overheat. Of course, it is possible to solder this way, but it will definitely not be neat or aesthetically pleasing

Always make sure you have the right welding current, gas flow and bond type available. If the weld is still porous despite this, you need to make sure that the material is of good quality. Sometimes steel is difficult to weld and it is almost impossible to make a perfect arc weld.

When can TIG welding be used?

TIG welding is considered a universal method. It is widespread for welding aluminium and its alloys. An alternating current is used. In addition to aluminium, TIG is also used for other non-ferrous metals such as magnesium, titanium, copper and nickel. It is suitable for all types of weldable steels (including stainless and acid-resistant steels). This method is usually recommended for joining thin sheets, e.g. car chassis. In addition to the automotive sector, it is also used in many other industries, including construction (various pipes and ducts), aviation and even the space industry.

TIG welder

A TIG welder is used to weld with the TIG method. There are many models available on the market that allow you to use TIG welding with direct and alternating current. These tools also allow welding to be performed with a covered electrode. The tools are very universal and can be used in various welding positions.

Before buying a welding machine, it is important to check for additional features that will later make your work easier. At the beginning of the article we mentioned smooth current regulation, which makes setting this parameter easier for novice welders. Being able to choose between 2T and 4T mode can also be useful.

The most important thing is experience with welding

Knowing the basics of inert gas welding with a non-consumable electrode, you can start stocking up on the necessary equipment: a TIG welder, electrodes and other necessary TIG accessories. Welders gain experience over many years, so don't be discouraged by early failures: uneven welds or overheated material. It is important to know the most common errors so that you can correct your own more easily. Continuously improving yourself is part of becoming an expert welder. Not only acquire new skills but also make the most of the ones you already have.