ANNEALING The primary purpose of annealing is to soften hard steel so that it maybe machined or cold worked. This is usually accomplished by heating the steel to slightly above the critical temperature, holding it htere until the remperature of the piece is uniform throughout, and then cooling at a slowly controlled rate so that […]
Tempering is possible because of the instability of the martensite, the principal constituent of hardened steel. Low temperature draws, from 300′ F to 400’F (150′ – 205′ C)
HARDENING Hardening is the process of heating a piece of steel to a temperature within or above its critcal range and then cooling it in rapidly. If the carbon content of the steel is known, the proper temperature to which the steel should be heated may be obtained by reference to the iron – iron […]
Steels having less than the eutectioid amount of carbon (less than 0.77%) are known as hypoeutectoid steels. Consider now the transfomation of such a material represented by cooling along line y – y’ in Fig 1.1. At high temperatures, the material is entirely austenite, but upon cooling enters a region where the stable phases are […]
The understanding of heat tratment is embraced by the broader study of metallurgy. Metallurgy is the physics, chemistry, and engineering related to metals from ore extraction to the final product. Heat treatment is the operation of heating and cooling a metal in its solid state to change its physical properties. According to the procedure used, […]