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Removing a quenched steel part before tempering

Aviation Mechanic General (AMG) practice question 33 of 33 on Aircraft Materials, Hardware, and Processes. ACS element AM.I.E.K2 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONA mechanic has hardened a steel part by quenching and intends to temper it. At approximately what temperature should the part be removed from the quenching bath?

  1. AAbout 900 °F, the annealing cool-out point
  2. BAbout 200 °F
  3. CRoom temperature, once the part is fully cool
Show the answer and explanation

Correct answer: B. About 200 °F

  • A — incorrect Cooling to 900 °F or lower before removal from the furnace belongs to the slow-cooling annealing procedure, not to removal from a quenching bath.
  • B — correct Because of the high internal stresses in the as-quenched condition, steel must be tempered just before it becomes cold, so the part is removed from the quenching bath at approximately 200 °F.
  • C — incorrect The range from 200 °F down to room temperature is the cracking range, so leaving the part in the bath until it is cold before tempering is what the procedure avoids.

BACKGROUND

Quenching leaves steel with high internal stresses in the as-quenched condition, so the metal must be tempered just before it becomes cold. The part should be removed from the quenching bath at a temperature of approximately 200 °F, because the temperature range from 200 °F down to room temperature is the cracking range. Tempering reduces the brittleness imparted by hardening, softens the steel, and produces definite physical properties. Tempering always follows, never precedes, the hardening operation, and it is conducted at temperatures below the low critical point of the steel. The minimum time at the tempering temperature should be 1 hour, increased by 1 hour for each additional inch of thickness on parts over one inch thick.

STUDY TIP

Remember the sequence and the number together: harden and quench, pull the part at about 200 °F, then temper immediately, because 200 °F down to room temperature is the cracking range. Do not confuse quench-bath removal temperatures with the furnace cooling temperatures used for annealing.

KEY POINTS

  • Steel must be tempered just before it becomes cold, so it leaves the quench bath at about 200 °F.
  • The range from 200 °F down to room temperature is the cracking range.
  • Tempering always follows hardening; it reduces brittleness and softens the steel.

SOURCES

  • FAA-H-8083-30B ch07 "Hardening"
  • FAA-H-8083-30B ch07 "Tempering"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.