Free AWS CWI Questions and Answers — Questions and Answers
Question 1: What discontinuities are visible when inspected visually?
- Cracks (Correct answer)
- Undercut
- Underfill
- All of the above
Correct answer: Cracks
Visual inspection is a non-destructive testing method that relies on the inspector's eyesight to detect surface discontinuities. Cracks are distinct breaks in the material that extend to the surface and are typically visible to the naked eye or with magnification. While other discontinuities like undercut and underfill are also visually detectable, cracks are a primary and critical type of defect identified through visual inspection.
Question 2: Key points to remember are:
- Established by the fabrication department
- Established after fabrication is accomplished
- Points where an inspection and acceptance are required prior to accomplishment for any further fabrication (Correct answer)
- Points where fabrication is put on hold
Correct answer: Points where an inspection and acceptance are required prior to accomplishment for any further fabrication
Key points, often referred to as 'hold points,' are critical stages in the fabrication process where work must stop until a designated inspection has been performed and accepted. This ensures that quality requirements are met at crucial junctures before subsequent steps, which might obscure or make defects difficult to correct, are undertaken. This proactive approach prevents costly rework and ensures overall product quality.
Question 3: One should measure the preheat temperature.
- The thickness of the joint but no less than 3 in from the joint at the beginning of the joint
- The thickness of the joint but no less than 3 in from the joint along the entire length of the joint (Correct answer)
- 1 in from the end of the joint
- At 6 in intervals along the length of the joint
Correct answer: The thickness of the joint but no less than 3 in from the joint along the entire length of the joint
Proper preheat temperature measurement is crucial for controlling cooling rates and preventing hydrogen-induced cracking in welds. The temperature must be measured at a specified distance from the weld joint, typically the material thickness but no less than 3 inches, to ensure the entire heat-affected zone is adequately heated. This measurement should be taken along the entire length of the joint to confirm uniform preheat before and during welding.
Question 4: Reviewing the drawings and specifications is recommended:
- During welding
- After welding
- Prior to welding
- All of the above (Correct answer)
Correct answer: All of the above
A Certified Welding Inspector (CWI) must review drawings and specifications throughout the entire welding project lifecycle. This includes prior to welding to understand requirements, during welding to ensure compliance with procedures, and after welding to verify the final product meets all acceptance criteria. Continuous review ensures adherence to design, process, and quality standards at every stage.
Question 5: Which discontinuity is thought to be the best served?
- Crack (Correct answer)
- Arc strike
- Slag inclusion
- Porosity
- Incomplete fusion
Correct answer: Crack
Cracks are generally considered the most critical and detrimental type of weld discontinuity because they can propagate rapidly under stress, leading to catastrophic failure of the welded structure. Unlike other discontinuities like porosity or slag inclusions, cracks represent a complete separation of material and significantly reduce the structural integrity and load-bearing capacity of the weld. Therefore, their detection and prevention are paramount in welding inspection.
Question 6: Which of the following discontinuities has a lower visual probability of being detected?
- Undercut
- Toe crack
- Overlap
- Lamellar tear (Correct answer)
- None of the above
Correct answer: Lamellar tear
Lamellar tears are internal discontinuities that occur within the base metal, parallel to the rolling surface, typically caused by through-thickness shrinkage stresses in highly restrained joints. Because they are subsurface and do not usually break the surface, they have a very low probability of being detected by visual inspection alone. Other methods like ultrasonic testing are required to find them.
Question 7: Of these welding techniques, which one can lead to underbead cracks?
- Welding on contaminated steels
- Use of wet electrodes
- Welding over paint
- All of the above. (Correct answer)
Correct answer: All of the above.
Underbead cracks, also known as hydrogen-induced cracks, are a serious type of cold crack that forms in the heat-affected zone (HAZ) beneath the weld bead. Welding on contaminated steels (e.g., with sulfur or phosphorus), using wet electrodes (introducing hydrogen), or welding over paint (introducing hydrogen and other contaminants) all increase the risk of hydrogen embrittlement and subsequent underbead cracking. Therefore, all these practices can contribute to this type of discontinuity.
Question 8: When the welding arc is improperly terminated, the resulting weld discontinuity is known as
- Overlap
- Undercut
- Incomplete fusion
- Crater crack (Correct answer)
- All of the above
Correct answer: Crater crack
A crater crack is a discontinuity that forms in the weld crater, the depression left at the end of a weld bead when the arc is extinguished. If the arc is terminated too abruptly, the molten metal in the crater solidifies rapidly and shrinks, creating tensile stresses that can lead to cracking in this localized area. Proper crater filling techniques are essential to prevent these cracks.
Question 9: Which of the following procedures is most unlikely to result in the presence of slag in a fully fused joint?
- PAW (Correct answer)
- SMAW
- SAW
- FCAW
Correct answer: PAW
Plasma Arc Welding (PAW) is a process that uses a constricted arc and typically does not employ a flux, unlike Shielded Metal Arc Welding (SMAW), Submerged Arc Welding (SAW), and Flux-Cored Arc Welding (FCAW). Since slag is a byproduct of flux melting and solidification, PAW is the least likely process among the options to produce slag inclusions in a fully fused joint.
Question 10: The discontinuity that arises from the gas being trapped inside the weld cross-section is known as
- Slag inclusion
- Crack
- Porosity (Correct answer)
- Incomplete fusion
Correct answer: Porosity
Porosity refers to gas pockets or voids trapped within the solidified weld metal. It occurs when gases, such as hydrogen, oxygen, or nitrogen, are absorbed into the molten weld pool and then do not escape before the metal solidifies. These trapped gas bubbles manifest as spherical or elongated holes within the weld cross-section, reducing its strength and integrity.
Question 11: When the welder moves too slowly, surplus weld metal flows out of the joint and lays on the base metal surface without fusing, resulting in what kind of weld discontinuity?
- Incomplete fusion
- Overlap
- Underfill (Correct answer)
- Undercut
Correct answer: Underfill
Underfill is a weld discontinuity characterized by a depression on the weld face or root surface that falls below the adjacent surface of the base metal. It indicates an insufficient amount of weld metal to completely fill the joint groove. While the question's description of 'surplus weld metal flowing out' more accurately describes overlap, underfill can occur if excessive heat from slow travel causes the molten metal to sag or burn through, preventing adequate fill of the joint.
Free AWS CWI Questions and Answers
What discontinuities are visible when inspected visually?