Definition
A heat-treatment process in which a metal part is heated to a temperature below its critical range, held there long enough for internal stresses to redistribute, and then slowly cooled. The process reduces residual stresses left in the material from forming, welding, machining, or rapid cooling, without significantly changing the part's hardness or basic mechanical properties.
Plain English
Heating a metal part to a moderate temperature and letting it cool slowly so that hidden internal tensions, left over from making or working the part, can settle out. The part keeps its strength but is less likely to warp or crack later.
Context Anchor
Seen in aircraft maintenance, especially when discussing welded steel parts, formed sheet metal, machined parts, and heat-treated components.
Derivation
From 'stress' (internal force locked inside a material) and 'relieve' (to ease or reduce). The name describes exactly what the process does: it eases the locked-in forces a part has been carrying since it was made or worked on.
Why Pilots Care
Residual stresses left in aircraft parts can cause sudden cracking or distortion in flight, compromising airframe integrity.
Grounding Statement
A welded bracket may look finished, but cooling after welding can leave hidden pull inside the metal; stress relieving reduces that hidden pull.
Intuition Check
Stress relieve does not mean reducing a pilot’s mental stress. Here it means reducing hidden physical stress inside a metal part.
Example Sentence 1
After welding the new tube into the engine mount, the technician stress relieved the assembly to prevent cracking in service.
Example Sentence 2
After machining the spar fitting, the shop followed the manual and stress relieved the part to prevent later distortion.