Annealing: A process of heating a metal to a high temperature and then cooling it slowly to reduce internal stresses and make it more ductile and soft. Annealing can also improve the machinability, electrical conductivity, and corrosion resistance of metals.
Quenching: A process of rapidly cooling a metal from a high temperature to increase its hardness and strength. Quenching can also create a martensitic structure in some steels, which is very hard and brittle.
Tempering: A process of reheating a quenched metal to a lower temperature and then cooling it to reduce the brittleness and increase the toughness and ductility. Tempering can also improve the impact resistance, wear resistance, and fatigue strength of metals.
Normalizing: A process of heating a metal to a high temperature and then cooling it in air to refine the grain structure and homogenize the composition. Normalizing can also improve the mechanical properties, such as hardness, strength, and toughness of metals.
