Process Annealing
Process annealing is a heat treatment that is used to negate the effects of cold work that is to soften and increase the ductility of a previously strain-hardened metal.
Stress Relieving
Internal residual stresses may develop in metal pieces in response to such things as cold working.
Distortion and warpage may result if these residual stresses are not removed. They may be eliminated by a stress relief annealing heat treatment in which the piece is heated to the recommended temperature, held
there long enough to attain a uniform temperature, and finally cooled to a room temperature in air. Stress relieving can eliminate some internal stresses without significantly altering the structure of the material.
Normalizing
Steels that have been plastically deformed by, for example, a rolling operation, consists of grains of
pearlite, which are irregularly shaped and relatively large, but vary substantially in size. Normalizing is an annealing heat treatment use to refine the grains and produce a more uniform and desirable size
distribution.
Normalizing is accomplished by heating the material to a temperature above its upper critical temperature. After sufficient time has been allowed for the alloy to completely transform to austenite, a procedure
termed austenitizing, the metal is allowed to cool in the air.
