Editing Metallurgy (section)

===Heat treatment===
[[File:Heat-Treating-Furnace.jpg|thumb|A heat treating furnace at {{convert|1800|F|abbr=on}}]]
Metals can be [[heat treatment|heat-treated]] to alter the properties of strength, ductility, toughness, hardness and resistance to corrosion. Common heat treatment processes include annealing, [[precipitation strengthening]], quenching, and tempering:<ref>Arthur Reardon (2011), ''Metallurgy for the Non-Metallurgist'' (2nd ed.), ASM International, {{ISBN|978-1615038213}}</ref>
* [[Annealing (metallurgy)|Annealing]] process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that, when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal.
* [[Quenching]] is the process of cooling metal very quickly after heating, thus "freezing" the metal's molecules in the very hard martensite form, which makes the metal harder.
* [[tempering (metallurgy)|Tempering]] relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.

Often, mechanical and thermal treatments are combined in what are known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high-alloy special steels, [[superalloy]]s and titanium alloys.