Which of the following is NOT a consequence of incorrect polarity in GMAW?

• A. Poor fusion
• B. Excessive spatter
• C. Arc instability
• D. Reduced porosity

Answer: (D)

Polarity in GMAW controls which electrode or workpiece is positive or negative, which in turn changes heat input, arc characteristics, and penetration. If polarity is not set correctly for the transfer mode being used, you typically see issues like poor fusion (not enough heat to fully fuse the weld to the base metal), arc instability (an erratic, wandering arc), and excessive spatter (droplets ejecting due to an unstable arc). Porosity, on the other hand, is mainly caused by shielding gas problems, contamination, moisture, or improper travel speed and technique, not directly by polarity. So reduced porosity isn’t a typical consequence of incorrect polarity, making it the correct choice for what is NOT a consequence.