Quenching (Rapid Cooling)
When applicable, the following more specific terms should be used: Direct Quenching, Fog Quenching, Hot Quenching, Interrupted Quenching, Selective Quenching, Slack Quenching, Spray Quenching, and Time Quenching.
Direct Hardening
Through hardening is applied to medium and high carbon parts that possess sufficient carbon content for hardening through the entire depth of the part. The parts are heated and quenched (cooled) to fix the structure of the part in a hardened state
Case hardening
Case hardening (or indirect hardening) is applied to low-carbon content steel parts to increase surface hardness. During case hardening, carbon molecules are introduced to the part via solids, liquids, or gases in a process known as carburizing.
Stress relieving
Annealing designed to relieve internal stresses caused by machining, welding, casting, cold working, quenching, or normalizing