What is the most common current type used in GTAW for aluminum welding?

The most common current type used in GTAW for aluminum welding is alternating current (AC). Aluminum is a material that benefits from the unique characteristics of AC welding, particularly because of its oxide layer. This oxide layer can create problems during the welding process if not properly managed.

With AC, the current alternates between positive and negative cycles. The positive cycle helps to clean the oxide layer from the aluminum surface, allowing for better fusion of the base metals. This cleaning action is critical for ensuring a strong weld. During the negative half of the cycle, the electron flow aids in penetration, allowing for deeper welding into the material.

Using AC ensures that the desirable properties of aluminum are preserved during welding while mitigating issues related to the oxide layer. This makes it the most effective choice for aluminum, unlike other current types which may not effectively handle these specific challenges.