Which of the following is true regarding the filler rod size for GTAW?

The correct answer highlights the relationship between the filler rod size and the diameter of the electrode used in Gas Tungsten Arc Welding (GTAW). In GTAW, the diameter of the filler rod should generally correspond to the size of the tungsten electrode, as well as to the thickness of the base materials being welded.

When welding, the filler rod must be chosen not only for compatibility with the base material but also for optimal matching with the electrode. If the electrode is too large and the filler rod is significantly smaller, it can lead to an imbalanced weld pool and affect the quality of the weld. Conversely, using a filler rod that is too large compared to the electrode can also lead to issues such as overheating or poor penetration.

Choosing the right filler rod size in relation to the electrode assists in achieving better fusion, and the correct balance of heat distribution and metal delivery, which are crucial for producing strong and defect-free welds.

Variations in filler rod size based on welding environment or specific requirements might be valid considerations, but they do not determine the fundamental relationship to the electrode diameter as pointed out in the correct choice. Thus, this answer encapsulates a fundamental principle of the GTAW process.