CRI Material Properties & Testing Standards 3 — Questions and Answers
Question 1: A material's ability to absorb energy up to fracture without failing is called:
- Elasticity
- Hardness
- Toughness (Correct answer)
- Stiffness
Correct answer: Toughness
Toughness is the total energy absorbed per unit volume up to fracture, represented by the area under the stress-strain curve.
Question 2: Which welding discontinuity is characterized by incomplete coalescence between the weld metal and the base metal fusion faces?
- Porosity
- Lack of fusion (Correct answer)
- Undercut
- Overlap
Correct answer: Lack of fusion
Lack of fusion is the absence of metallurgical bond between weld metal and base metal at the fusion zone.
Question 3: The IQI (image quality indicator) sensitivity is expressed as:
- The smallest visible hole diameter divided by part thickness
- The wire diameter or hole diameter visible as a percentage of part thickness (Correct answer)
- The ratio of SFD to OFD
- The ratio of kV to mA used during exposure
Correct answer: The wire diameter or hole diameter visible as a percentage of part thickness
IQI sensitivity = (smallest visible wire or hole size / part thickness) × 100%, indicating the minimum detectable feature size.
Question 4: Carbon equivalent (CE) is used primarily to predict:
- Weld bead width
- Susceptibility to hydrogen-induced cracking (Correct answer)
- Grain size after normalizing
- Charpy impact energy at −40°F
Correct answer: Susceptibility to hydrogen-induced cracking
Carbon equivalent formulas estimate hardenability and risk of hydrogen cracking in the heat-affected zone.
Question 5: Which type of crack typically initiates at the toe of a weld and runs parallel to the weld bead?
- Hot crack
- Underbead crack
- Toe crack (Correct answer)
- Crater crack
Correct answer: Toe crack
Toe cracks form at the weld toe due to stress concentration and hydrogen embrittlement in the HAZ.
Question 6: ASTM E747 wire IQIs must be placed on which side of the test object relative to the film?
- Film side
- Source side (Correct answer)
- Either side if geometry allows
- Midplane of the specimen
Correct answer: Source side
IQIs are placed on the source side of the object to maximize sensitivity and ensure the least favorable imaging geometry is demonstrated.
Question 7: Which material defect results from segregation of alloying elements during solidification, producing bands of differing composition?
- Piping
- Banding (Correct answer)
- Lapping
- Seaming
Correct answer: Banding
Banding is caused by compositional segregation during solidification, subsequently elongated by rolling, visible as alternating light/dark bands.
CRI Material Properties & Testing Standards 3
A material's ability to absorb energy up to fracture without failing is called: