What is meant by overheating a metal with an oxyacetylene torch?

• A. Heating to the melting point
• B. Heating rapidly without changing properties
• C. Heating to a temperature that impairs the metal
• D. Heating to make the metal harder

Answer: (C)

Overheating means pushing the metal to a temperature beyond what it can safely handle without its properties deteriorating. When metal is overheated with an oxyacetylene torch, its internal structure can change, leading to loss of hardness or ductility, distortion, and a higher risk of cracking. So the idea is heating to a temperature that impairs the metal, not just heating, melting, or a intentional hardening.