Plasma-Transferred Arc Welding (PTA Welding)

Definition - What does Plasma-Transferred Arc Welding (PTA Welding) mean?

Plasma-transferred arc (PTA) welding is a thermal process for applying wear- and corrosion-resistant layers on surfaces of metallic materials. It is a versatile method of depositing high-quality metallurgically fused deposits on relatively low-cost surfaces.

The PTA process is used in instances of extreme demands on wear resistance. It is applied to various components in a variety of industries, such as:

  • Oil & gas - Used to combat wear, erosion, abrasion and corrosion
  • Automobiles - Used for hardfacing engine valves
  • Power generation - Used for high-pressure steam turbine nozzles and induced-draft fan blades

Corrosionpedia explains Plasma-Transferred Arc Welding (PTA Welding)

The plasma-transferred arc welding process provides a high-strength metallurgical bond, which is formed between the superalloy coating overlay and the underlying component, ensuring that the coating does not become compromised even under the highest of stresses. Soft alloys, medium- and high-hardness materials, and carbide composites can be deposited on a variety of substrates to achieve diverse properties such as:

  • Mechanical strength
  • Wear and corrosion resistance
  • Creep

The high-energy plasma arc melts the surface of the base material. At the same time, the powdery filler material is inserted into the arc and is molten. During solidification, a substance-to-substance bond between the filler material and the base material is created.

PTA welding has several significant advantages over traditional welding processes. The PTA method of welding takes advantage of the ability to control the shape and direction of the plasma plume used in all methods of electric arc welding. Other key points include:

  • PTA is a high-energy, low-heat, inert gas welding process.
  • PTA provides minimal dilution and high resistance to chipping because of its dense metallurgical structure, free of voids, oxide films, and discontinuities.
  • Used on parts subject to corrosion, thermal shock, severe abrasion, slurry erosion, or extreme impact forces to increase component life.

Benefits of plasma-transferred arc welding include:

  • High productivity
  • High quality of powder deposits
  • Significantly lower cost for hardfacing

Thus, many surface properties needed for special applications can be economically produced by PTA welding.

Applications of PTA welding include:

  • Downhole drilling tools
  • High-wear piping components / slurry transport
  • Ground engagement equipment for oil sands / mining industries
  • Breaker screens
  • Valve components
  • Areas where traditional wire-based overlays such as chromium carbide are not providing significant wear life

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