What polarity is typically used for welding metals such as aluminum and magnesium?

Welding metals like aluminum and magnesium typically requires alternating current (AC), as it provides several advantages essential for effective weld quality in these materials.

AC polarity is particularly beneficial for aluminum welding because it allows for a cleaning action on the surface of the material, which is crucial when working with aluminum. This cleaning effect is achieved through the balance of positive and negative cycles present in AC welding. During the positive half-cycle, the tungsten electrode experiences a cleaning effect that removes the aluminum oxide layer, which can impede the welding process. The negative cycle, on the other hand, allows for effective penetration and heat generation needed for a solid weld.

Moreover, while some specialized techniques may allow for DC welding with aluminum (such as using specific filler materials and conditions), AC remains the most universally accepted and used method for welding aluminum and magnesium. This is due to its capability to manage cleanliness and provide the necessary heat input characteristics for these materials, ensuring a strong and reliable weld joint.