The Skill Of Tantalum Welding

The skill of welding Tantalum

Tantalum (Ta) is a refractory metal; and so, it has an incredibly high melting point (5425). As is typical of such a class of metal, Ta may present some of the same characteristics as refractive ones. A good example is its high affinity for nitrogen and oxygen at high temperatures. The density and thermal conductivity of Ta are relatively high as well. Refractory metals were initially used in the aerospace industry, but welding has made it possible to utilise them in more applications. However, Ta has several challenges that make it necessary to get skilled people for welded parts.

For one, the high temperatures generated in the processes means that exposing the metal to the atmosphere will cause it to bond with other elements. Ta has a tendency to turn brittle when exposed to impurities also. A refractory metal becomes brittle when it reaches a certain temperature where it transitions from being ductile. When there is contamination during the process, the transition temperature can go up, thereby turning the metal brittle at room temp.

Ta has an affinity for gettering, which is why any process must be conducted in an area free from contamination. To achieve this, professional welders use several options.

Open Air

Trying to weld Ta in an open air environment is extremely tricky for the reasons mentioned before. Only the simplest products can get away with this technique because welders have to follow stringent shielding measures. Shielding has to be present for the arcs, back, sides and front, and that takes immense skill. Welders use trailing shields to provide a constant flow of an inert gas to prevent impurities from landing on the metal surfaces. Usually, they have extra large gas cups to cover the weld zone with the gas.

Flow Purge Chamber

When the open air process is not possible due to the complexity of product angles, then this method becomes the most suitable. It also works when dealing with a large project where other chambers would not provide enough space. The flow purge chamber contains argon gas and is constructed with a polyethene sheet and masking tape. During the process, the gas flows over the metal and displaces any air that is trapped; hence, providing an ideal environment to weld.

Electron Beam

Welds constructed through the electron beam method are of very high standards. The technique demands the most advanced equipment, thus the need for professional services. This process favours welds with the most intricate details such as parts of different cross sections and fillets. Parts that are tough to reach would be best served by this method because it takes advantage of narrow weld zones and has very good penetration.

Dry Box/Vacuum Purge

With this technique, welders use a dry box to provide high-quality inert gas surroundings for the Tantalum parts. After placing the components in the box, the chamber is sealed then the vacuum is pulled on the box and pumped to the required microns. Argon gas is filled in the box to attain a slight positive pressure before welders begin their tasks.

The process welders use vary from one company to another, but each one presents significant challenges. Ta welds demand the use of inert gases, which results in high costs. The level of cleanliness necessary calls for meticulous techniques because; once the metal spoils, it cannot be repaired. Dirt, fingerprints, oil, grease and paint are just a few of the substances that can render a whole production useless if they come into contact with the metal. Welding companies have the right settings to ensure that this does not happen. Professional welders also have the right tools to facilitate the process of manufacturing Ta welds without messing with the integrity of the metal.

Posted on: Dec 12, 2016