What is the difference between AC and DC welding currents?

• A. AC is used for copper, while DC is for aluminum
• B. DC alternates direction, while AC flows in one direction
• C. AC alternates direction, while DC flows in one direction
• D. Both AC and DC are used for stainless steel

Answer: (C)

The distinction between AC (alternating current) and DC (direct current) welding currents is fundamentally based on their flow characteristics. In AC, the electrical current periodically switches direction, which means it alternates between positive and negative phases. This alternating nature allows for certain advantages in welding applications, such as improved cleaning action on the weld area, particularly when working with materials like aluminum.

On the other hand, DC flows in only one direction, providing a more stable and consistent arc. This characteristic of DC is beneficial for creating deep penetration in welds, making it a preferred choice for welding thicker materials and for processes like TIG (Tungsten Inert Gas) welding.

Understanding the differences in how these currents behave is crucial for selecting the right welding technique for specific materials and applications. Thus, the correct distinction highlights the nature of AC and DC currents in welding, reflecting their respective advantages and best use cases.