What type of current is used in gas tungsten arc welding (GTAW)?

• A. Direct current (DC) or alternating current (AC)
• B. Only direct current (DC)
• C. Only alternating current (AC)
• D. Pulsed current only

Answer: (A)

In gas tungsten arc welding (GTAW), both direct current (DC) and alternating current (AC) can be employed, making the first option the correct response. Direct current is primarily used for welding materials like steel or stainless steel, as it provides a stable arc and better control over the welding process. This control is vital for achieving high-quality welds.

On the other hand, alternating current is particularly beneficial when welding aluminum or magnesium. AC helps in cleaning the oxide layer that forms on the surface of these metals during welding, allowing better fusion and stronger welds. The capability to use both types of current allows versatility in GTAW, enabling welders to adapt their approach based on the material they are working with.

The other options are overly restrictive; suggesting only direct current or only alternating current ignores the multifaceted nature of GTAW. Similarly, specifying only pulsed current overlooks the foundational use of DC and AC in the process, which are essential for a wider range of applications. Understanding the correct use of both types of current is key to mastering the GTAW process and producing quality welds across various materials.