Weld Discontinuities & Defects Flashcards
7 cards from real AWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
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According to AWS standards, which type of discontinuity is generally considered most critical because it can propagate under cyclic or service loading?
Answer: Cracks
Cracks are the most critical weld discontinuity because they act as sharp stress concentrators and can propagate under service stresses, potentially leading to brittle or fatigue fracture.
Excessive weld reinforcement (excess weld metal above the base metal surface) is most likely caused by:
Answer: Too low a welding current or too slow a travel speed with excess filler deposition
Excessive reinforcement results from depositing too much weld metal per pass, typically caused by low travel speed, which allows the pool to build up rather than spread evenly.
On a radiograph (X-ray film), incomplete fusion at the fusion line typically appears as:
Answer: A straight or slightly wavy dark line parallel to the weld fusion line
Incomplete fusion appears as a straight or slightly wavy dark linear indication on a radiograph, positioned at or near the fusion line, reflecting the unbonded gap between weld metal and base metal.
What is the AWS-recommended repair procedure when a crack is discovered in a completed weld?
Answer: Completely excavate the crack plus a minimum distance beyond each end before rewelding
AWS requires that cracks be completely removed, including excavating beyond each visible end to ensure the entire crack is eliminated, before rewelding the joint.
Overlap in a fillet weld is primarily caused by:
Answer: Too low a welding current combined with too slow a travel speed
Overlap forms when welding current is too low to melt the base metal surface adequately, and slow travel speed deposits excess weld metal that flows over the base metal without fusing.
Which nondestructive testing (NDT) method is most effective for detecting subsurface (internal) porosity in a weld?
Answer: Radiographic testing (RT) or ultrasonic testing (UT)
Radiographic testing (RT) and ultrasonic testing (UT) are volumetric methods capable of detecting internal discontinuities such as subsurface porosity that are not accessible from the surface.
Burn-through (melt-through) in a weld is most likely to occur when:
Answer: Welding thin base metal with excessive heat input or current
Burn-through occurs when the weld pool melts completely through the base metal, and is most common on thin sections where excessive heat input overwhelms the material's ability to support the molten pool.