CWI Destructive Testing and Properties 5 — Questions and Answers
Question 1: A peel test is most commonly used to evaluate:
- Butt weld root penetration
- Fusion in resistance spot welds or small-diameter fillet welds (Correct answer)
- Submerged arc weld quality
- Electroslag weld integrity
Correct answer: Fusion in resistance spot welds or small-diameter fillet welds
The peel test is used for thin sheet resistance spot welds and small fillet welds to evaluate nugget size or fusion at the root by peeling apart joined pieces.
Question 2: During a Brinell hardness test, the hardness number (BHN) is calculated using the applied load and:
- The depth of the indentation
- The surface area of the spherical indentation (Correct answer)
- The diagonal of the square indentation
- The rebound height of the indenter
Correct answer: The surface area of the spherical indentation
The BHN is the applied load divided by the curved surface area of the spherical indentation produced by the ball indenter.
Question 3: What type of fracture surface appearance in a nick-break test indicates good weld quality?
- Completely smooth, glass-like surface
- Coarse, granular surface with visible cracks
- Fine-grained, silky appearance with no cracks, voids, or excessive slag (Correct answer)
- Layered, lamellar surface with slag lines
Correct answer: Fine-grained, silky appearance with no cracks, voids, or excessive slag
An acceptable nick-break fracture exhibits a fine-grained, dense surface free of cracks, incomplete fusion, porosity exceeding code limits, or excessive slag inclusions.
Question 4: Which test method is used to determine the transition temperature between ductile and brittle fracture behavior in steel?
- Bend ductility test at room temperature
- Charpy V-notch impact testing at multiple temperatures (Correct answer)
- Vickers hardness traverse across the HAZ
- Transverse tensile test at elevated temperature
Correct answer: Charpy V-notch impact testing at multiple temperatures
Charpy impact tests conducted across a range of temperatures generate a ductile-to-brittle transition curve used to determine the transition temperature.
Question 5: What is the minimum acceptable bend angle for most AWS D1.1 guided bend qualification tests?
- 90 degrees
- 120 degrees
- 150 degrees
- 180 degrees (Correct answer)
Correct answer: 180 degrees
AWS D1.1 requires that bend specimens be bent to 180 degrees (U-shape) without cracks exceeding specified limits on the tension surface.
Question 6: Modulus of elasticity (Young's modulus) is determined from the tensile test as:
- The slope of the plastic deformation region
- The slope of the linear elastic region of the stress-strain curve (Correct answer)
- The area under the entire stress-strain curve
- The ratio of ultimate strength to yield strength
Correct answer: The slope of the linear elastic region of the stress-strain curve
Young's modulus is the ratio of stress to strain in the elastic (linear) region of the stress-strain curve, representing material stiffness.
Question 7: In a transverse weld tensile test, if the specimen breaks in the base metal at a stress exceeding the minimum specified tensile strength, the test result is:
- Rejected because it did not break in the weld
- Accepted because the minimum strength requirement was met (Correct answer)
- Inconclusive and must be retested
- Rejected because base metal failure invalidates the weld test
Correct answer: Accepted because the minimum strength requirement was met
A base metal fracture above the minimum specified tensile strength demonstrates the weld is at least as strong as the base metal, which is acceptable.
CWI Destructive Testing and Properties 5
A peel test is most commonly used to evaluate: