Laser heat treatment, also known as laser quenching or laser phase transformation hardening, is a process in which a high-energy laser beam is used to quickly scan the workpiece, causing the surface temperature of the irradiated metal or alloy to rise above the phase transformation point at an extremely fast rate. When the laser beam leaves the irradiated area, due to thermal conduction, the cold substrate rapidly cools down and undergoes self cooling quenching to obtain a finer hardened layer structure, with a hardness generally higher than that of conventional quenching.