AWS Destructive & Non-Destructive Testing 3 — Questions and Answers
Question 1: What NDT method is most effective for detecting subsurface laminar discontinuities in steel plate?
- Liquid penetrant testing
- Magnetic particle testing
- Ultrasonic testing (Correct answer)
- Visual testing
Correct answer: Ultrasonic testing
Ultrasonic testing can detect internal planar and laminar flaws through the full thickness of steel plate, which surface methods cannot reach.
Question 2: A Charpy V-notch impact test evaluates which mechanical property of a weld or base metal?
- Hardness
- Toughness (notch impact energy) (Correct answer)
- Tensile strength
- Yield strength
Correct answer: Toughness (notch impact energy)
The Charpy V-notch test measures absorbed energy during fracture, quantifying toughness and transition temperature behavior.
Question 3: In magnetic particle testing, a circular magnetization technique is best suited for detecting which flaw orientation?
- Longitudinal cracks parallel to the current flow (Correct answer)
- Transverse cracks perpendicular to the weld axis
- Subsurface voids below 6 mm depth
- Laminar tears in the base metal
Correct answer: Longitudinal cracks parallel to the current flow
Circular magnetization creates flux lines encircling the conductor, making it most sensitive to longitudinal (axial) discontinuities.
Question 4: Which destructive test is specifically designed to assess the ductility of a weld by wrapping the specimen around a fixed-radius die?
- Nick-break test
- Guided bend test (Correct answer)
- Hardness test
- Tensile test
Correct answer: Guided bend test
The guided bend test bends the weld specimen around a plunger of specified radius to reveal cracks and evaluate ductility and fusion.
Question 5: An IQI (image quality indicator) in radiographic testing is used to verify:
- The correct film density is achieved
- The sensitivity and quality of the radiographic image (Correct answer)
- That porosity exceeds the acceptance limit
- Proper penetrant dwell time
Correct answer: The sensitivity and quality of the radiographic image
The IQI (penetrameter) demonstrates that the radiographic technique has sufficient sensitivity to detect discontinuities of a specified size.
Question 6: When performing dye penetrant testing on an austenitic stainless steel weld, which pre-cleaning method is NOT recommended?
- Solvent wiping
- Steam cleaning
- Acid pickling without neutralization (Correct answer)
- Mechanical brushing with stainless wire brush
Correct answer: Acid pickling without neutralization
Acid residues left in discontinuities after pickling without neutralization can mask penetrant indications and produce false-negative results.
Question 7: A hardness test result on a weld HAZ that significantly exceeds the base metal hardness may indicate:
- Excessive preheat was applied
- Susceptibility to hydrogen-induced cracking (Correct answer)
- Incomplete penetration in the root
- Inadequate arc voltage
Correct answer: Susceptibility to hydrogen-induced cracking
High HAZ hardness (typically above 350 HV) indicates a martensitic microstructure that is susceptible to hydrogen-assisted cold cracking.
AWS Destructive & Non-Destructive Testing 3
What NDT method is most effective for detecting subsurface laminar discontinuities in steel plate?