FREE Certified Welder Weld Inspection and Defects 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?

Accepted Answer

Slag Inclusions

Answer

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?

Accepted Answer

Inadequate shielding gas flow

Answer

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'?

Accepted 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]

Answer

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?

Accepted Answer

The weld's soundness and ductility

Answer

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?

Accepted Answer

Undercut

Answer

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]

Certified Welder Practice Test

Certified Welder Practice Test

FREE Certified Welder Weld Inspection and Defects Questions and Answers