Heat treatment is a method used to alter the physical, and sometimes chemical, properties of a material. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of a material. Techniques in heat treatment include annealing, case hardening, precipitation strengthening, tempering and quenching. This book reviews current research in the study of heat treatments including the heat treatment of vitrified grinding wheels; fog-quenching after heat treatments for big cylindrical parts in rolling mills; an analysis of the yield strength and of the ageing and quenching heating temperature in aluminium alloys; heat treatment of 18% nickel maraging steels and the thermal treatment of wood at high temperatures as an alternative environment friendly wood modification technology.