CFS Fastener Testing & Quality Control 2 — Questions and Answers
Question 1: Which ASTM standard governs proof load testing for inch-series bolts?
- ASTM A307
- ASTM F606 (Correct answer)
- ASTM A563
- ASTM F3125
Correct answer: ASTM F606
ASTM F606 specifies mechanical test methods for externally and internally threaded fasteners, including proof load testing.
Question 2: A fastener fails a wedge tensile test but passes a standard axial tensile test. What does this indicate?
- The material has low ductility under combined loading (Correct answer)
- The heat treatment was improperly applied
- The thread form is out of tolerance
- The fastener grade is too high for the application
Correct answer: The material has low ductility under combined loading
Wedge tensile testing evaluates a fastener's ability to sustain combined tensile and bending loads; failure indicates insufficient ductility under such conditions.
Question 3: What is the purpose of a Rockwell hardness test on a fastener?
- To measure surface roughness
- To verify heat treatment and estimate tensile strength (Correct answer)
- To determine corrosion resistance
- To check thread pitch accuracy
Correct answer: To verify heat treatment and estimate tensile strength
Rockwell hardness correlates with tensile strength and confirms that heat treatment achieved the required mechanical properties.
Question 4: Which sampling plan standard is most commonly referenced for fastener incoming inspection in the US?
- ISO 9001
- ANSI/ASQ Z1.4 (Correct answer)
- MIL-STD-105
- ASTM E2234
Correct answer: ANSI/ASQ Z1.4
ANSI/ASQ Z1.4 provides attribute sampling procedures widely used for lot-by-lot inspection of fasteners.
Question 5: What does a hydrogen embrittlement relief bake accomplish after electroplating?
- Improves adhesion of the zinc coating
- Drives absorbed hydrogen out of the base metal (Correct answer)
- Increases coating thickness uniformity
- Reduces internal thread friction
Correct answer: Drives absorbed hydrogen out of the base metal
The bake at temperatures typically around 375°F–450°F for several hours allows hydrogen to diffuse out before it can cause delayed fracture.
Question 6: During a coating thickness inspection, a magnetic induction gauge reads higher than expected on a steel bolt. What is the most likely cause?
- The coating is too thin
- A thicker-than-specified coating was applied
- The bolt is made of stainless steel
- The gauge was not zeroed on uncoated substrate (Correct answer)
Correct answer: The gauge was not zeroed on uncoated substrate
Magnetic induction gauges must be zeroed on bare substrate of the same material; failure to do so produces falsely high readings.
Question 7: Which test is used to verify that a self-locking nut maintains its locking torque after multiple installation cycles?
- Salt spray test
- Prevailing torque test per ASTM F2329 (Correct answer)
- Torque-tension test
- Cross-threading evaluation
Correct answer: Prevailing torque test per ASTM F2329
Prevailing torque testing per standards such as ASTM F2329 or IFI-100/107 measures the torque required to run a nut on and off a bolt over successive cycles.
CFS Fastener Testing & Quality Control 2
Which ASTM standard governs proof load testing for inch-series bolts?