Brandon, thank you for asking this question instead of just accepting the very common, yet totally false, use of the term "temper" to refer to the entire heat treatment. Tempering is indeed a heat treatment, but it is just one of very many; hardening, annealing, stress relieving, normalizing etc... are all heat treatments. Most often when people say "heat treat" what they are referring to is the hardening operation and this is the one most often erroneously referred to as tempering. Tempering is actually a treatment done after hardening to counteract some of the effects of the quenching operation. Hardening involves heating above 1425F and then cooling very quickly in order to achieve hardness and strength, but often also results in brittleness. Tempering is a process of heating above 350F in order to relieve some of the stress and increase toughness.
