FAA Aviation Mechanic Airframe (AMA)Airframe StructuresHard
A technician is solution heat treating a 2024-T3 aluminum repair skin in preparation for forming. After removing the part from the furnace at the specified soaking temperature, what is the maximum allowable delay before the part must be quenched to retain proper corrosion resistance and mechanical properties?
- A30 seconds
- B60 seconds
- C5 minutes
- D10 seconds
Show answer & explanationAnswer & explanation
Correct answer: D. 10 seconds
Aluminum alloy parts must be quenched within 10 seconds of removal from the solution heat treating furnace. A longer delay allows the alloying elements to begin precipitating out of solid solution at the grain boundaries, reducing corrosion resistance and mechanical strength.
Why the other options are wrong
- A. 30 seconds still exceeds the allowable delay and risks reduced corrosion resistance.
- B. 60 seconds is far too long; precipitation would already have degraded the alloy's properties.
- C. 5 minutes would result in complete loss of the solution heat treatment benefits.
Solution Heat Treatment Quench Delay
Aluminum alloys must be quenched within 10 seconds of removal from the solution heat treating furnace to prevent premature precipitation at grain boundaries.
- Maximum quench delay: 10 seconds
- Delay risk: loss of corrosion resistance and strength
- Followed by natural or artificial aging (T4/T6)
Memory trick: 10 seconds: count to ten, then dunk it in!