AWS A5.12 Classification

AWS A5.12 is an American Welding Society (AWS) specification that classifies non-consumable tungsten electrodes used in various arc welding and cutting processes. Here's a breakdown of the key information:

• Focus: Unlike AWS A5.9, A5.10, and A5.11 that deal with consumable electrodes that melt and contribute filler metal to the weld, AWS A5.12 focuses on non-consumable electrodes. These electrodes, typically made of tungsten or tungsten alloyed with other elements like lanthanum, cerium, or thorium, do not melt during welding but instead provide an electrical path and create heat for the welding process.

• Applications: Non-consumable tungsten electrodes classified under AWS A5.12 are used in various arc welding and cutting processes, including:

  • Gas Tungsten Arc Welding (GTAW): Also known as TIG welding, this process utilizes a tungsten electrode and an inert gas shield to create high-quality welds on various metals.
  • Plasma Arc Welding (PAW): This process uses a specialized torch that creates a high-temperature plasma stream using a tungsten electrode and inert gases for welding or cutting.
  • Thermal Spraying: Tungsten electrodes can be used in thermal spraying processes to create coatings on various surfaces.

• Classification System: AWS A5.12 assigns a classification code to each tungsten electrode based on its chemical composition and properties. The code helps identify the most suitable electrode for a specific welding or cutting application depending on factors like:

  • Current Type: AC (alternating current) or DC (direct current) welding.
  • Material being welded: Different metals might require specific tungsten properties for optimal performance.

• Code format: The AWS A5.12 classification code typically follows a format like EWP (where W can be a letter or number). Here's a basic breakdown:

  • E: This prefix signifies an electrode.
  • W: This denotes tungsten or tungsten alloy.
  • P: This letter signifies specific properties or dopants added to the tungsten, such as Lanthanum (La), Cerium (Ce), or Zirconium (Zr). The absence of a letter after W might indicate pure tungsten (EWP).

• Additional Information: The AWS A5.12 specification is based on ISO 6848, an international standard for the classification of non-consumable tungsten electrodes. The AWS specification might include some modifications or additional informative annexes.