Heat Treating involves heating (or chilling) a metal alloy at extreme temperature to manipulate its crystalline microstructure. This process affects the mechanical behavior of the metal, altering its hardness, strength, ductility, or elasticity properties. Heat treating alters material dimensionally by growing or shrinking it- and in some cases both, depending upon the material and direction. For this reason, many materials cannot be machined to final dimensions before the heat treating process, and instead, require a pre- and post-heat treat machining process.