CRI Material Properties & Testing Standards 2 — Questions and Answers
Question 1: Which ASTM standard governs reference radiographs for steel castings?
- ASTM E186 (Correct answer)
- ASTM E94
- ASTM E155
- ASTM E747
Correct answer: ASTM E186
ASTM E186 provides reference radiographs for heavy-walled (2–4.5 in.) steel castings.
Question 2: The ultimate tensile strength of a material is best described as:
- The stress at which permanent deformation begins
- The maximum stress a material can withstand before fracture (Correct answer)
- The stress at which necking initiates
- The modulus of elasticity under tension
Correct answer: The maximum stress a material can withstand before fracture
Ultimate tensile strength is the peak engineering stress on the stress-strain curve before fracture.
Question 3: Which material property describes resistance to localized plastic deformation caused by indentation?
- Toughness
- Hardness (Correct answer)
- Ductility
- Resilience
Correct answer: Hardness
Hardness quantifies a material's resistance to permanent surface indentation or scratching.
Question 4: Laminar discontinuities in plate material are most parallel to which surface?
- Transverse cross-section
- Rolled surface (plate face) (Correct answer)
- Through-thickness direction
- Weld fusion line
Correct answer: Rolled surface (plate face)
Laminations are elongated along the rolling direction and lie parallel to the plate face due to the rolling process.
Question 5: When radiographing austenitic stainless steel welds, grain noise is most problematic because:
- The alloy absorbs nearly all radiation
- Coarse grains cause preferential etching
- Large grains scatter radiation, creating mottled images (Correct answer)
- Austenite has higher density than ferritic steel
Correct answer: Large grains scatter radiation, creating mottled images
Coarse austenitic grains scatter X-rays or gamma rays non-uniformly, producing a mottled or 'grass' background.
Question 6: According to ASME Section V, the maximum permitted film density for radiographic examination using X-ray is:
- 1.8 to 4.0
- 2.0 to 4.5 (Correct answer)
- 2.5 to 5.0
- 1.5 to 3.5
Correct answer: 2.0 to 4.5
ASME Section V Article 2 requires film densities between 2.0 and 4.0 for X-ray, with 4.5 permitted when a densitometer is used.
Question 7: Porosity in a weld radiograph appears as:
- Linear dark indications with sharp edges
- Rounded or spherical dark spots (Correct answer)
- Light linear streaks along the weld centerline
- Irregular light areas indicating excess penetration
Correct answer: Rounded or spherical dark spots
Gas pores are spherical voids that transmit more radiation, appearing as rounded dark spots on the radiograph.
CRI Material Properties & Testing Standards 2
Which ASTM standard governs reference radiographs for steel castings?