A LEVEL PRODUCT DESIGN - HEAT TREATMENTS

Question	Answer
Annealing	A process of heating a metal that gas been hardened. 'Soaking' the metal at an appropriate annealing temperature allows the crystals to reshape, so relieving the internal stresses that cause work hardening.
Hardening	Carried out by heating the metal (usually steel) to cherry red, followed by rapid cooling (quenching). Usually followed by tempering to remove brittleness.
Tempering	Carried out after hardening to remove brittleness, the metal is cleaned to its natural grey colour, heat is then applied and when the correct colour is seen then the material is rapidly cooled.
Normalising	This allows the crystal structure to become uniform, a piece of work is heated until the crystal structure begins the change, this temperature is maintained until all crystals are refined. It is the cooled in air to create added toughness

Resource summary

	Created by charlotte-clayto almost 10 years ago