ITMC Welding Fundamentals 2 — Questions and Answers
Question 1: Which welding defect is characterized by incomplete fusion between the weld metal and the base metal along the weld toe?
- Porosity
- Undercut
- Lack of fusion (Correct answer)
- Overlap
Correct 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.
Question 2: In GMAW (MIG welding), what is the function of the shielding gas?
- To preheat the base metal
- To protect the weld pool from atmospheric contamination (Correct answer)
- To flux the weld puddle
- To increase arc voltage
Correct 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.
Question 3: What does the term 'duty cycle' refer to in welding equipment?
- The amperage output rating
- The percentage of a 10-minute period a welder can operate at rated output (Correct answer)
- The number of weld passes per hour
- The electrode feed rate
Correct 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.
Question 4: Which electrode classification is used for low-hydrogen SMAW electrodes?
- EXX10
- EXX11
- EXX18 (Correct answer)
- EXX13
Correct answer: EXX18
Electrodes ending in 8 (such as E7018) have a low-hydrogen iron powder coating that minimizes moisture and hydrogen in the weld.
Question 5: What causes spatter in GMAW welding?
- Excessive preheat temperature
- Incorrect shielding gas flow rate only
- Voltage too high or wire feed speed too low relative to voltage (Correct answer)
- Using DCEN polarity
Correct 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.
Question 6: A welder notices the weld bead is narrow and has excessive convexity. What is the most likely cause?
- Travel speed too slow
- Amperage too high
- Travel speed too fast (Correct answer)
- Electrode angle incorrect toward the joint
Correct answer: Travel speed too fast
Excessive travel speed reduces heat input, resulting in a narrow, highly convex bead that may also have poor fusion.
Question 7: Which type of weld joint is most commonly used when two plates meet at a 90-degree angle to form a T-shape?
- Butt joint
- Lap joint
- T-joint (fillet weld) (Correct answer)
- Corner joint
Correct 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.
ITMC Welding Fundamentals 2
Which welding defect is characterized by incomplete fusion between the weld metal and the base metal along the weld toe?