Welding Fundamentals Flashcards

Which welding defect is characterized by incomplete fusion between the weld metal and the base metal along the weld toe?

Answer: Lack of fusion

Lack of fusion occurs when the weld metal fails to completely bond with the base metal or previous weld pass at the fusion zone.

In GMAW (MIG welding), what is the function of the shielding gas?

Answer: To protect the weld pool from atmospheric contamination

Shielding gas in GMAW surrounds the arc and molten weld pool to prevent oxygen, nitrogen, and hydrogen from contaminating the weld.

What does the term 'duty cycle' refer to in welding equipment?

Answer: The percentage of a 10-minute period a welder can operate at rated output

Duty cycle is the percentage of a 10-minute period that a welding machine can operate at its rated amperage without overheating.

Which electrode classification is used for low-hydrogen SMAW electrodes?

Answer: EXX18

Electrodes ending in 8 (such as E7018) have a low-hydrogen iron powder coating that minimizes moisture and hydrogen in the weld.

What causes spatter in GMAW welding?

Answer: Voltage too high or wire feed speed too low relative to voltage

Spatter in GMAW is commonly caused by an imbalance between voltage and wire feed speed, producing an unstable arc that expels molten droplets.

A welder notices the weld bead is narrow and has excessive convexity. What is the most likely cause?

Answer: Travel speed too fast

Excessive travel speed reduces heat input, resulting in a narrow, highly convex bead that may also have poor fusion.

Which type of weld joint is most commonly used when two plates meet at a 90-degree angle to form a T-shape?

Answer: T-joint (fillet weld)

A T-joint is formed when one member is positioned perpendicular to another, typically welded with fillet welds on each side.