Free Certified Welder Weld Inspection and Defects Questions and Answers 1 — Questions and Answers
Question 1: During a visual inspection of a multi-pass fillet weld made with FCAW, the inspector finds non-metallic particles trapped between the weld beads. What is this type of defect called?
- Porosity
- Slag Inclusions (Correct answer)
- Undercut
- Lack of Fusion
Correct answer: Slag Inclusions
Slag inclusion is a defect where slag, a non-metallic byproduct of flux-based welding processes like FCAW and SMAW, becomes trapped within the weld metal or between weld passes. [7, 13] This commonly occurs due to improper cleaning between passes or incorrect technique. [5, 10] Porosity is gas pockets, undercut is a groove at the weld toe, and lack of fusion is a failure of the weld metal to fuse with the base metal or a previous bead. [3]
Question 2: A welder performing a GMAW (MIG) weld on carbon steel notices numerous small, spherical cavities on the surface of the completed weld. Which of the following is the MOST likely cause of this porosity?
- Travel speed is too slow
- Amperage is set too high
- Inadequate shielding gas flow (Correct answer)
- The work clamp has a poor connection
Correct answer: Inadequate shielding gas flow
Porosity is caused by gas becoming trapped in the solidifying weld metal. [8, 28] In GMAW, the primary cause is contamination of the weld pool by the atmosphere, which occurs when there is inadequate shielding gas coverage. [6, 15] This can be due to low flow rates, drafts, excessive nozzle-to-work distance, or spatter buildup in the nozzle. [22, 23]
Question 3: In the terminology of weld inspection, what is the critical difference between a 'discontinuity' and a 'defect'?
- A discontinuity is internal, while a defect is on the surface.
- A discontinuity is an interruption in the material, while a defect is a discontinuity that exceeds code limits and is cause for rejection. [4, 17] (Correct answer)
- A discontinuity is only found with destructive testing, while a defect can be found with visual inspection.
- A 'discontinuity' and a 'defect' are interchangeable terms for the same flaw.
Correct answer: A discontinuity is an interruption in the material, while a defect is a discontinuity that exceeds code limits and is cause for rejection. [4, 17]
A discontinuity is any interruption in the uniform structure of a material, such as porosity, an inclusion, or a crack. [12, 17] A discontinuity only becomes a defect when it is determined to be unacceptable according to the applicable code or standard, meaning it is too large or severe and compromises the integrity of the weld. [4, 19, 24] Therefore, all defects are discontinuities, but not all discontinuities are defects. [19]
Question 4: A welder's qualification test plate undergoes a guided side bend test. After being bent 180 degrees, the exposed weld surface shows several open flaws. What does this destructive test primarily evaluate?
- The weld's chemical composition
- The weld's electrical resistance
- The weld's tensile strength
- The weld's soundness and ductility (Correct answer)
Correct answer: The weld's soundness and ductility
A guided bend test is a destructive method used to assess the quality of a weld. [1, 2] It primarily evaluates the weld's soundness (freedom from internal flaws like lack of fusion or porosity) and ductility (the ability to deform without fracturing). [9, 14] When the specimen is bent, any significant internal discontinuities will be revealed as cracks or openings on the stretched surface. [9, 14]
Question 5: A visual inspection reveals a sharp groove melted into the base metal along the toe of the weld, which has not been filled by the weld metal. What is this specific defect called?
- Overlap
- Undercut (Correct answer)
- Incomplete Penetration
- Excessive Reinforcement
Correct answer: Undercut
Undercut is a groove melted into the base metal adjacent to the weld toe or root and left unfilled by weld metal. [3, 27, 33] It acts as a stress concentrator and can weaken the joint, especially under fatigue loading. [35] Common causes include excessive current, incorrect electrode angle, or excessive travel speed. [34]
Question 6: An inspector is using a non-destructive testing method on a ferromagnetic steel weldment. The process involves inducing a magnetic field and applying fine iron particles to the surface. This method is most effective for detecting which type of defects?
- Internal porosity deep within the weld
- Incorrect alloy composition
- Surface and near-surface discontinuities like cracks (Correct answer)
- Incorrect grain structure in the heat-affected zone
Correct answer: Surface and near-surface discontinuities like cracks
This scenario describes Magnetic Particle Testing (MT or MPI). [11, 26] This NDT method is used on ferromagnetic materials to detect discontinuities that are on the surface or very close to the surface, such as cracks, laps, and seams. [18, 21] The iron particles are attracted to the magnetic flux leakage field created by a discontinuity, making the flaw visible. [16]
Free Certified Welder Weld Inspection and Defects Questions and Answers 1
During a visual inspection of a multi-pass fillet weld made with FCAW, the inspector finds non-metallic particles trapped between the weld beads.
What is this type of defect called?