Quenching involves cooling heated metal in oil or water.

• A. True
• B. False
• C. Not specified
• D. Sometimes

Answer: (A)

Quenching is a heat‑treatment step where a heated metal is cooled rapidly to change its internal structure. Immersing the hot piece in a quenching medium speeds up heat removal from the surface, and oil or water are the most common choices for that rapid cooling. Water provides very fast cooling, which can yield very hard structures but may risk cracking or distortion if the piece is large or improperly tempered. Oil cools more gradually, helping to reduce cracking while still producing the desired changes in hardness and microstructure. So saying quenching involves cooling heated metal in oil or water matches the typical practice and serves as a practical, general description of the process. There are other quench media, like air or polymer coolants, used in specific situations, but the fundamental idea remains: rapid cooling in a medium.