The Difference Between Thorium and Cerium
There are 5 main types of electrodes to consider when doing any kind of welding: Pure Tungsten, 2% Ceriated, 1.5% Lanthanated, 2% Ziroconiated, and 2% Thoriated. These are all non-consumable for GTAW or TIG welding applications. The most common types of tungsten user for orbital welding are Ceriated, however in some rare circumstances, welders do use thoriated.
What exactly is tungsten?
Tungsten is a hard, grayish-white metal that is extracted from the mineral’s wolframite and scheelite. It is classified as a transition metal on the periodic table of elements and has the highest melting point and lowest vapor pressure of any element. It is also one of the heaviest elements that is found naturally on Earth.
The name "tungsten" comes from the Swedish words "tung" "sten", which translates to "heavy stone". The symbol for tungsten is W, which stands for Wolframium. Chemically, tungsten is relatively inert. Compounds have been prepared, however, in which the element has oxidation states from 0 to +6. The states above +2, especially +6, are most common. It is also mostly a non-reactive element meaning it does not react with water, is immune to attack by most acids and bases, and does not react with oxygen or air at room temperature, making it ideal for welding.
Ceriated tungsten: Ceriated electrodes contain a minimum of 97.3% tungsten, with 1.8% to 2.2% cerium, and are used for low current settings. These electrodes have a low-amp arc and when paired with a properly calibrated weld head like an AMI 8-2000 or Magnatech 820 create seamless welds. Most orbital welding applications use ceriated tungsten as it is easier to shape and polish as well as its superior arc-starting capabilities in a controlled environment (within a weld head). Ceriated tungsten also has limited exposure to radiation unlike in thoriated. These electrodes using AC welding at low current settings and the AMI and Magnatech power supplies can be connected to 110 or 220. (Refer to our manuals for more information) Most AMI and Magnatech weld heads perform exceptionally better and last longer when using ceriated tungsten electrodes over thoriated.
Thoriated Tungsten: There are a lot of benefits to thoriated tungsten, but those benefits are mostly found in plasma welding not orbital. 2% Thoriated is superior to pure tungsten electrodes since they have a higher electron output, better arc-starting and arc stability on plasma welding applications, can in some cases run faster, and have higher current-carrying capacities. It is possible to use 2% thoriated tungsten electrodes for AC welding, but they excel for negative polarity grid welding on carbon and stainless steel, nickel, and titanium with DC electrodes. MIT recommends orbital welders use ceriated tungsten with our weld heads as the radiation decay and exposure left behind when using thoriated can contaminate work surfaces and grinding tools requiring extended cleaning when changing rods or workpieces. Side note, welding operators should always read their MSDS before using thoriated tungsten 2%. Thoriated tungsten electrodes contain low levels of radioactivity and could pose health risks if they are not used according to manufacturer’s specifications.
Cheap Tungsten vs Expensive Tungsten
Regardless of the tungsten you choose, the quality of the product is vital to the integrity of the weld. Cheap tungsten sourced from China and India has benefits, especially when it comes to price, however, they are typically mixed with other metals that can affect weld quality. Tungsten from Europe (namely Germany, Austria, and Switzerland) are typically higher quality. They have a more stable arc, better arc performance in humid environments, and greater tolerance of currents. 2% ceriated tungsten also has better weld penetration at lower amperage giving welders a better opportunity to complete welds on smaller diameter tubes. This is a game changer for aerospace engineers and welders in high purity facilities.
So, What Tungsten Electrodes Should You Choose?
We're aware that this is a loaded question to ask in general, but when it comes to Orbital Welding, 2% ceriated tungsten is a perfect choice. If shaped and polished correctly, ceriated tungsten can create great welds on stainless steel tube and carbon steel pipes. Keep in mind, orbital welding electrodes are specially ground and polished to achieve high precision, consistent, and quality welds. Because of the unique head shape orbital welding tungsten delivers a different penetration compared to standard tipped tungsten. Be sure to check your electrode prior to striking an arc as a misshaped electrode can cause undesirable results.
We're aware that this is a loaded question to ask in general, but when it comes to Orbital Welding, 2% ceriated tungsten is a perfect choice. If shaped and polished correctly, ceriated tungsten can create great welds on stainless steel tube and carbon steel pipes. Keep in mind, orbital welding electrodes are specially ground and polished to achieve high precision, consistent, and quality welds. Because of the unique head shape orbital welding tungsten delivers a different penetration compared to standard tipped tungsten. Be sure to check your electrode prior to striking an arc as a misshaped electrode can cause undesirable results.