WCL Inspection & Quality Control 3 — Questions and Answers
Question 1: What is the minimum preheat temperature requirement primarily intended to prevent?
- Distortion of the base metal
- Hydrogen-induced cracking (Correct answer)
- Excessive spatter
- Incomplete fusion at the root
Correct answer: Hydrogen-induced cracking
Preheat is primarily used to slow the cooling rate and allow hydrogen to diffuse out of the weld, preventing hydrogen-induced (cold) cracking.
Question 2: During visual inspection of a completed weld, a CWI finds a crack. What is the appropriate action?
- Apply paint to seal the crack
- Mark and reject the weld for repair (Correct answer)
- Grind smooth and re-inspect
- Accept if less than 1/16 inch long
Correct answer: Mark and reject the weld for repair
Cracks are rejectable under all major welding codes; the CWI must mark and reject the weld so it can be repaired per an approved repair procedure.
Question 3: What does the term 'heat-affected zone' (HAZ) refer to?
- The molten weld pool during welding
- Base metal area altered by welding heat but not melted (Correct answer)
- The area covered by the welding arc
- The region of the weld with highest hardness only
Correct answer: Base metal area altered by welding heat but not melted
The HAZ is the portion of the base metal that has not melted but whose microstructure and properties have been altered by the heat of welding.
Question 4: A CWI using magnetic particle testing on a carbon steel weld would NOT be able to detect:
- Surface cracks
- Near-surface subsurface cracks
- Internal porosity 1 inch below the surface (Correct answer)
- Linear indications at the weld toe
Correct answer: Internal porosity 1 inch below the surface
Magnetic particle testing is effective only for surface and near-surface (typically within 1/4 inch) discontinuities and cannot reliably detect defects deep within the material.
Question 5: What is the purpose of a nick-break test in weld inspection?
- To measure the tensile strength of the weld
- To expose the internal cross-section for visual examination (Correct answer)
- To determine the impact toughness at low temperatures
- To verify electrode classification
Correct answer: To expose the internal cross-section for visual examination
A nick-break test fractures a weld sample to expose the internal cross-section, allowing visual examination for porosity, slag inclusions, and incomplete fusion.
Question 6: Which discontinuity is most likely to be found at the weld root in a single-sided groove weld?
- Overlap
- Slag inclusion
- Incomplete joint penetration (Correct answer)
- Underfill
Correct answer: Incomplete joint penetration
Incomplete joint penetration (IJP) commonly occurs at the weld root of single-sided groove welds when the weld metal does not extend through the full thickness of the joint.
Question 7: What standard AWS publication governs structural welding of steel?
- AWS D1.1 (Correct answer)
- AWS D1.2
- AWS B2.1
- ASME Section IX
Correct answer: AWS D1.1
AWS D1.1 Structural Welding Code—Steel is the primary standard governing the welding of structural steel in the United States.
WCL Inspection & Quality Control 3
What is the minimum preheat temperature requirement primarily intended to prevent?