Technology and Engineering Atlas

How Things Are Built
Methods

Annealing

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Annealing is a heat treatment that heats a material, usually metal or glass, to a controlled temperature and then cools it slowly, relieving internal stresses, softening the material and refining its internal crystal structure. It is commonly applied after cold working, casting or welding, all of which otherwise leave a material hardened, stressed and brittle.

Facts
Disputed
Origin Year
3000 BCE 2
Ancient metalworkers were annealing copper by around the third millennium BCE to counteract the brittleness cold hammering introduced; a single point of origin is not established.
Core Principle
Heating a worked or cast material to a controlled temperature and cooling it slowly, to relieve internal stress, soften the material and refine its crystal structure. 1
Cross-Tradition Connections

Associated With

Forging, Methods

Forged and cold-worked metal is frequently annealed afterward to relieve the stresses working introduced.

Welding, Methods

Welded joints are sometimes annealed afterward to relieve the thermal stress welding introduces.

In Field

Sources
1. Annealing (Wikipedia)
Wikipedia contributors, Wikimedia FoundationLead section
Quote, Lead section
annealing is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and reduce its hardness, making it more workable.
View the Source
2. A History of Technology
Charles Singer, E. J. Holmyard, A. R. Hall and Trevor I. Williams, editors, Oxford University Press, 1954
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