TIG stands for Tungsten Inert Welding, and in a more technical sense, it’s known as Gas Tungsten Arc Welding (GTAW). The process utilizes a non-consumable tungsten electrode that relays current to the welding arc. There are various tungsten electrodes that you can use for the process, but not all will prove efficient. Keep on reading to find out what tungsten to use for TIG welding.
Types of Tungsten Electrodes
Choosing the right electrode is a critical part of an efficient welding procedure. The type and size of the electrode vary with the kind of metal and the joint. In this article, we will mention a few popular electrode choices and their uses.
Pure Tungsten – Green
Pure tungsten electrodes comprise of 99.5% tungsten, which means it balls easily. The ball tip shape also gives the arc excellent stability. They work particularly well with magnesium and aluminum alloys and are ideal for application with low to medium amperage requirements. Pure tungsten only works well with an AC power supply.
Rare Earth is one of the elements that are added to pure tungsten. The American Welding Society’s (AWS) classification for Rare Earth is EWG. All Rare Earth electrodes contain an unspecified mix of natural additives; however, manufacturers have to specify the composition percentage of each material present on the packaging.
The combination you choose will depend upon the desired results and the metals being welded. The multiple available combinations allow you to ensure that the arc is stable and that you can achieve optimal weld penetration.
Rare Earth electrodes also allow you to use smaller diameter electrodes, relay higher current levels and produce less tungsten spitting than other types of electrodes.
Thoriated tungsten electrodes contain 97.3% tungsten and 1.7-2.2% thorium oxide. They have low radioactivity and high current carrying ability, making them highly suitable for arc welding procedures. They are long-lasting and easy to use, which is an added advantage.
Thorium oxide electrodes are ideal for use with a DC power supply. They have high melting points and can take significant amounts of heat with minimal melting. They are suitable for use on thinner steel plates, as they have average corrosion rates and moderate amperage requirements.
However, thorium oxide emits alpha particles that are hazardous for human beings. Replacing thorium oxide with rare earth removes the health risks attached to the particles while keeping many of the benefits.
Thorium electrodes are ideal for a few particular AC welding jobs, such as thin-gauge aluminum and material less than 0.060 inches thick. They’re also the right choice for specific DC welding jobs on carbon steel, stainless steel, nickel, and titanium.
These comprise of 97% tungsten and around 1.3 -1.7 % lanthanum. Lanthanated electrodes are only ideal for use with Direct Current power sources. Lanthanum enhances the electrodes’ current carrying capacity by 50%.
Striking an arc is relatively more comfortable with Lanthanum electrodes, and these electrodes have amazing arc stability, excellent re-ignition properties, and low burn-off rates. They are useful when it comes to welding the following materials:
- Aluminum alloys
- Magnesium alloys
- Nickel alloys
Ceriated electrodes are made of 97.3% tungsten and 1.8-2.2 % cerium oxide and are known as 2% Ceriated electrodes. They are ideal for low-current AC applications, but it’s possible to use them for some DC applications.
If you need to weld small delicate parts or are working with thin metal sheets, pipe fabrication, or orbital tube manufacturing, then Ceriated electrodes are the right electrodes for you. Some compounds metals that they can be used with are:
- non-corroding steels
- copper alloys
They are long-lasting electrodes with excellent ignition and re-ignition capabilities. They produce exceptionally stable arcs and can be used at low amperage ranges as well. With low erosion rates, ceriated tungsten proves better than pure tungsten as it offers better current carrying properties.
Zirconiated electrodes consist of 99.1% pure tungsten and 0.15-0.4 Zirconium. They prove beneficial in cases when tungsten produces intolerable levels of contamination. They can handle higher amperage levels and have increased ball retention, making them excellent for magnesium and aluminum alloys.
They work particularly well with AC and are highly resistant to splitting. They have high current-carrying ability and produce very stable arcs. However, unlike most other electrodes, zirconiated electrodes are not suitable for use with Direct Current.
Direct Current Power Supply
In Direct Current power sources, there’s only a one-way flow of current. The current flows from positive to negative or negative to positive. Smaller devices like batteries, phones, flashlights, or remote controls use a DC power source.
Welders use both positive to negative as well as the other way round in their welding procedures. Using a DC supply is more beneficial than an Alternate Current supply for multiple reasons.
- A DC supply is ideal for welders who require faster deposit rates
- Produces very little spatter
- Gives a smoother weld
- Higher production yield
- A consistent and stable electrical arc
- Requires special equipment
- Unsuitable for aluminum
- High-intensity heat production
- High-risk procedure
When using Direct Current power sources, take extra care. The danger of a magnetic field build-up is prevalent in DC welding, which can cause the arc to blow up. It is ideal for stainless steel TIG welding, vertical welding, single carbon brazing, and numerous other procedures.
Alternating Current Power Supply
An AC power source alternates the current flow from positive to negative and negative to positive around 120 times per second, depending upon the frequency of the supply. Throughout the cycle, the current keep switching direction, giving you the advantages of DC power while reducing some drawbacks.
- A little bit of arc cleaning
- It is compatible with most electrodes
- Provides good metal fusion
- Gives excellent penetration levels
- Supports numerous types of welds like heavy plates, aluminum TIG weld, and even fast-fill
- Suitable for magnetized metal welding
- Ideal for higher temperature welds
- Great for repair work
However, one major drawback of using an AC power supply is its directional instability, which directly affects product yield.
Tungsten exhibits the necessary balling properties, primarily when used with an AC power supply. However, the metal has minimal heat-resisting properties and needs to be manipulated to increase heat resistance as well as current-carrying ability. Rare-earth, lanthanum, thorium, cerium, and zirconium add to tungsten and improve its ball maintaining capability. They help in point maintenance in the electrodes.
The production efficiency of TIG welding directly depends upon the use of an electrode, the power supply, the choice of shield gas, and the welding job.
Use commercially available varieties when using rare-earth tungsten electrodes.
Ceriated and Lanthanated electrodes are ideal for both AC and DC welding because of their performance and because they are radiation-free. You can use them for all welding jobs, and they are easily comparable to thoriated electrodes.
Thoriated electrodes do not ball up evenly, but they carry amperage very well. With thorium oxide, you can use a smaller electrode. It is commonly used with an AC power supply.
Zirconiated electrodes produce extremely stable arcs and are highly resistant to splitting. They perform better than thorium in AC welding.
What color Tungsten should be used for stainless steel?
The thoriated red electrode is ideal for stainless steel welds. It provides the optimal heat generation, bead formation, and weld penetration to give smoother welds.
What is the best Tungsten for an aluminum inverter?
A pure tungsten electrode or a zirconiated tungsten electrode works best with AC aluminum welds. If you’re using a tungsten electrode, make sure it’s large enough in diameter to carry the welding current efficiently. An AC power supply requires the use of larger diameter electrodes to reduce resistance.
What is blue Tungsten for?
Blue tungsten is a good substitute for thorium oxide. It provides proper arc ignition and is more long-lasting than thoriated electrodes. It can be used for both AC and DC welding with both transformer and inverter power sources.