Definition
A heat treatment process applied to hardened steel in which the metal is reheated to a temperature below its critical point, held for a specified time, and then cooled. Tempering reduces the brittleness produced by hardening while retaining most of the strength, producing a tougher, more usable metal.
Plain English
After steel is hardened it becomes very strong but also brittle, so it can crack or shatter. Tempering is a second, gentler heating that takes some of that brittleness out so the part is still hard but no longer prone to snapping.
Context Anchor
Seen in aircraft maintenance when discussing heat treatment of steel parts, tools, springs, and other metal hardware.
Derivation
From the Latin 'temperare,' meaning 'to mix in proper proportion' or 'to moderate.' The sense fits well: tempering moderates the extreme hardness of quenched steel into a balanced mix of strength and toughness.
Why Pilots Care
Aircraft parts must withstand repeated flight loads without fracturing; correctly tempered metal provides the necessary toughness to prevent in-flight failure.
Intuition Check
Tempering does not mean simply heating metal to make it harder. In this context, it means controlled reheating after hardening to make the metal less brittle and more usable.
Example Sentence 1
After hardening the steel shaft, the technician tempered it at 400°F to reduce brittleness before returning it to service.
Example Sentence 2
Proper tempering of the landing gear component allowed it to absorb repeated landing impacts without developing cracks.