Which current type is preferred for welding ferrous metals in GTAW?

In Gas Tungsten Arc Welding (GTAW), direct current (DC) is generally preferred for welding ferrous metals. This is largely due to the stability and control that DC provides during the welding process. When using DC, the welder can achieve a more consistent arc, which is essential for producing high-quality welds in ferrous materials like steel and stainless steel.

DC welding allows for effective penetration and control over heat input, making it suitable for a variety of thicknesses and joint designs in ferrous applications. The heat generation is concentrated at the arc, enabling better fusion of the base metals, which is crucial for ensuring strength and integrity in the weld.

Using alternating current (AC), while effective for materials such as aluminum and magnesium, can introduce variability in the heat distribution, which is not ideal for ferrous materials where precise control is required. The other current types, such as pulsed current and high frequency current, also serve specific purposes in certain scenarios but are not the primary choice for standard ferrous welding applications. Therefore, the preference for DC in GTAW for ferrous metals stems from its effectiveness in delivering a stable and reliable weld.