Thermal Treatments (Heat-Treating):
Heat-treating is a term used to describe all of the controlled heating and cooling operations performed on a material in the solid state for the purpose of altering its microstructure and/or properties. The major objectives of the different kinds of thermal treatments are: Soften the material for improved workability. Increase the strength or hardness of the material. Increase the toughness or resistance to fracture of the material. Stabilize mechanical or physical properties against changes that might occur during exposure to service environments. Insure part dimensional stability. Relieve undesirable residual stresses induced during part fabrication. Different metals respond to treatment at different temperatures. Each metal has a specific chemical composition , so changes in physical and structural properties take place at different and critical temperatures. Depending on the thermal treatment used, the atomic structure and/or microstructure of a material may change