Definition
A heat-treatment process in which a metal is heated to a specified temperature and then cooled slowly, usually in the furnace or in still air, to soften it, relieve internal stresses, and improve its ability to be machined or formed.
Plain English
Heating a metal and letting it cool slowly so it becomes softer and easier to work with.
Context Anchor
Seen in aircraft maintenance, repair, and materials discussions, especially when describing how metal parts are formed, repaired, or heat-treated.
Derivation
From the Old English onaelan, meaning 'to set on fire' or 'to bake.' The original sense was simply to heat something in a fire. In metalwork it took on the more specific meaning of heating and slow-cooling to soften the material.
Why Pilots Care
Annealed metal behaves differently from hardened metal. A pilot or owner involved in maintenance decisions should know that some parts must be annealed before bending or forming, and that some materials (like certain aluminum alloys) age-harden again over time after annealing.
Intuition Check
Anneal does not mean simply heating a part with a torch. The important point is the planned heating and cooling process that changes how the material behaves.
Example Sentence 1
The mechanic annealed the copper tubing before bending it to fit around the firewall.
Example Sentence 2
After the repair weld cooled, the technician annealed the fitting to restore flexibility.