What determines the polarity used during GTAW?

The polarity used during Gas Tungsten Arc Welding (GTAW) is primarily determined by the type of tungsten electrode being utilized. Different tungsten electrodes have varying characteristics that affect their performance based on polarity.

For instance, the most common tungsten electrodes, like pure tungsten and various alloys, have specific polarities that optimize their stability and longevity. When using a direct current electrode negative (DCEN) polarity, which is the most common for GTAW, it draws more heat to the workpiece and tends to give deeper penetration. This makes it suitable for welding thicker materials and more robust joints. Conversely, using alternating current (AC) is beneficial for non-ferrous materials like aluminum and magnesium, as it allows for better cleaning of the oxide layer while providing adequate heat input.

The other factors, such as the thickness of the material, welding position, and desired heat input, certainly play important roles in the overall welding process but do not directly dictate the polarity choice. Polarity is closely linked to the properties of the tungsten electrode, making it the central determinant in this context.