Welding Certification — Knowledge Practice
Defects and discontinuities: practice questions
Our Welding Knowledge bank has 15 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.
Question 1
What causes slag inclusions in multi-pass SMAW welds?
- Too much shielding gas
- Not removing slag completely between passes
- Welding in the flat position, which traps slag in the root
- Using a low-hydrogen rod
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B. Not removing slag completely between passes — Clean each pass thoroughly.
Question 2
What is a common cause of hydrogen cracking?
- Moisture in electrodes or on the joint, combined with high hardness and restraint
- Using too little filler
- Welding in the overhead position
- Using argon gas
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A. Moisture in electrodes or on the joint, combined with high hardness and restraint — Low-hydrogen practices and preheat reduce it.
Question 3
What is undercut?
- Excess weld metal on the face
- A groove melted into the base metal at the toe of the weld and left unfilled
- Slag trapped in the weld
- Gas pockets in the weld
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B. A groove melted into the base metal at the toe of the weld and left unfilled — Common causes: too much amperage, too fast travel or incorrect angle.
Question 4
Which discontinuity is generally considered the most serious?
- Cracks
- Slight spatter
- Minor discolouration
- Small surface ripples
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A. Cracks — Cracks can grow under load and cause failure.
Question 5
What is incomplete (lack of) fusion?
- Porosity at the surface
- Weld metal not properly fused to the base metal or previous passes
- Too much penetration
- An oversized weld
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B. Weld metal not properly fused to the base metal or previous passes — Often due to low heat or poor technique.