How does AC concentrate welding heat when compared to DC?

The correct understanding of how AC concentrates welding heat involves recognizing the distinct characteristics in the heat distribution between the workpiece and the tungsten electrode. When using alternating current (AC) in Gas Tungsten Arc Welding (GTAW), the heat is distributed in a way that provides a balance between the workpiece and the tungsten.

In AC welding, the alternating polarities allow the tungsten to experience a cleaning action during the positive half-cycle, which helps to remove contaminants from the surface of the workpiece. However, this does not mean that all of the heat is concentrated solely on one or the other. AC does create a more balanced heat distribution because the current alternates direction, allowing for both sides to benefit from the heat generated during the welding process.

This equal heat distribution is critical for applications involving aluminum and magnesium, where proper heat management is essential for achieving sound welds. With DC, the heat concentration tends to favor either the workpiece or the tungsten depending on the polarity used, whereas AC achieves a more balanced thermal effect on both.

Thus, the characteristic of equal heat on the work and tungsten during AC welding is vital in ensuring effective welds with good penetration and cleaning action, which is why this answer accurately reflects the principles of heat concentration in