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Annealing occurs by the diffusion of atoms within a solid material, so that the material progresses towards its equilibrium state. Heat increases the rate of diffusion by providing the energy needed to break bonds. The movement of atoms has the effect of redistributing and eradicating the dislocations in metals and (to a lesser extent) in ...
In ferrous alloys, annealing is usually accomplished by heating the metal beyond the upper critical temperature and then cooling very slowly, resulting in the formation of pearlite. In both pure metals and many alloys that cannot be heat treated, annealing is used to remove the hardness caused by cold working.
However, the process does not use extreme variations of temperature and therefore chemically strengthened glass has little or no bow or warp, optical distortion, or strain pattern. This differs from toughened glass, in which slender pieces can be significantly bowed.
Diagram of a cross section of a katana, showing the typical arrangement of the harder and softer zones. Differential hardening (also called differential quenching, selective quenching, selective hardening, or local hardening) is most commonly used in bladesmithing to increase the toughness of a blade while keeping very high hardness and strength at the edge.
Annealing is a process of slowly cooling hot glass objects after they have been formed, to relieve residual internal stresses introduced during manufacture. Especially for smaller, simpler objects, annealing may be incidental to the process of manufacture, but in larger or more complex products it commonly demands a special process of annealing in a temperature-controlled kiln known as a lehr. [1]
Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and some steels, stainless steels, and duplex stainless steel.
Solvent vapor annealing (SVA) is a widely used technique for controlling the morphology and ordering of block copolymer (BCP) films. [1] [2] [3] By controlling the block ratio (f = NA/N), spheres, cylinders, gyroids, and lamellae structures can be generated by forming a swollen and mobile layer of thin-film from added solvent vapor to facilitate the self-assembly of the polymer blocks. [4]
The effects of cold working may be reversed by annealing the material at high temperatures where recovery and recrystallization reduce the dislocation density. A material's work hardenability can be predicted by analyzing a stress–strain curve, or studied in context by performing hardness tests before and after a process. [8] [9]