Red Seal Welding Practice Exam

When an E4918 electrode is used and the arc is pulsing, what is the likely cause?

1. Correct polarity

2. Wrong polarity

3. Overheated electrode

4. Underheated electrode

The correct answer is: Wrong polarity

Pulsing arc is a welding technique that alternates the current between two voltage levels to control heat input. By using E4918 electrodes, the welding process involves a high amperage with low arc voltage. Therefore, using the wrong polarity in this process can interrupt the pulsing flow of current and result in an inconsistent arc, affecting the weld quality. This makes option B, Wrong polarity, the likely cause of the issue. Options A, C, and D are all incorrect because polarity is the main factor in this scenario. Using correct polarity will maintain the pulsing arc and prevent overheating or under heating of the electrode and ensure smooth welding.