Final answer:
Correct Option is B) .The most commonly used type of welding current for the GTAW process with aluminum is alternating current (AC), because it provides the necessary cleaning action for aluminum's oxide layer.
Step-by-step explanation:
When welding aluminum with the GTAW (Gas Tungsten Arc Welding) process, the most commonly used type of welding current is alternating current (AC). This is because AC current allows for the cleaning action that is essential for removing the oxide layer from the aluminum, which aids in the welding process. In contrast, direct current (DC) flows continuously in one direction and is often used for other types of materials. However, when it comes to aluminum, AC is preferred due to its ability to change direction at regular time intervals, which helps to break up the oxide layer that forms on the aluminum surface during welding.
It's important to note that the option of pulsed current is available and is sometimes used when welding aluminum, as it allows for greater control over the heat input and can improve weld quality. However, AC remains the most popular choice for the GTAW process with aluminum.