CWI Destructive Testing and Properties 4 — Questions and Answers
Question 1: A side bend test is most commonly used for:
- Thin sheet welds under 3/8 inch
- Thick plate welds to evaluate through-thickness soundness (Correct answer)
- Pipe welds only
- Overlay cladding welds
Correct answer: Thick plate welds to evaluate through-thickness soundness
Side bend tests are typically required for base metal thicknesses 3/8 inch (10 mm) and greater to examine the full through-thickness cross-section.
Question 2: What does a Charpy test temperature requirement primarily protect against?
- Creep failure at elevated temperatures
- Brittle fracture at low or sub-zero service temperatures (Correct answer)
- Stress corrosion cracking
- Fatigue crack propagation
Correct answer: Brittle fracture at low or sub-zero service temperatures
Charpy testing at specified minimum temperatures verifies that the material retains adequate toughness to resist brittle fracture in cold service conditions.
Question 3: In a fillet weld break test, which discontinuity would be considered a failure?
- Slag inclusions less than 1/8 inch in length
- Incomplete fusion at the root (Correct answer)
- Slight convexity of the weld face
- Minor spatter adjacent to the weld
Correct answer: Incomplete fusion at the root
Incomplete fusion at the root is a rejectable defect revealed by the fillet weld break test because it compromises load-carrying capacity.
Question 4: What is the gauge length used to calculate percent elongation typically related to?
- The total specimen length
- The cross-sectional area or a fixed multiple of the specimen diameter (Correct answer)
- The fracture surface area
- The radius of the test mandrel
Correct answer: The cross-sectional area or a fixed multiple of the specimen diameter
Gauge length is standardized relative to specimen cross-section, commonly 2 inches for flat specimens or 4× or 5× the diameter for round specimens.
Question 5: Which property describes a material's ability to absorb energy during plastic deformation before fracturing?
- Hardness
- Toughness (Correct answer)
- Stiffness
- Yield strength
Correct answer: Toughness
Toughness is the ability to absorb energy and plastically deform without fracturing, represented by the area under the stress-strain curve.
Question 6: The guided bend test mandrel diameter is specified to control:
- Specimen temperature during bending
- The outer fiber strain imposed on the weld (Correct answer)
- The rate of bending force application
- The fracture location in the weld
Correct answer: The outer fiber strain imposed on the weld
The mandrel diameter determines the bend radius, which directly controls the outer fiber strain experienced by the weld during the test.
Question 7: Reduction of area in a tensile test is calculated by comparing the original cross-sectional area to:
- The minimum cross-sectional area at the fracture (Correct answer)
- The area at the 0.2% offset yield point
- The area at ultimate tensile strength
- The area after elastic recovery
Correct answer: The minimum cross-sectional area at the fracture
Reduction of area is calculated as ((A₀ − Af) / A₀) × 100%, where Af is the minimum cross-sectional area at the fracture location.
CWI Destructive Testing and Properties 4
A side bend test is most commonly used for: