Heat treatment of steel.
2022-04-22
There are many types of heat treatment processes available for steel. The most common are annealing, quenching and tempering. Heat treatment is effective for eutectoid components (hypereutectoids) with a carbon content of more than 0.8%, but not for hypoeutectoid steels.
Annealing is the process of heating steel to a temperature high enough to release localized internal stresses. It does not soften the product as a whole, but only locally relieves strains and stresses within the material. Annealing goes through three stages: recovery, recrystallization and grain growth. The annealing temperature required for a particular steel depends on the type of annealing to be achieved and the alloy composition.
Annealing is the process of heating steel to a temperature high enough to release localized internal stresses. It does not soften the product as a whole, but only locally relieves strains and stresses within the material. Annealing goes through three stages: recovery, recrystallization and grain growth. The annealing temperature required for a particular steel depends on the type of annealing to be achieved and the alloy composition.
Quenching involves heating the steel to create an austenite phase and then quenching in water or oil. This rapid cooling results in a hard but brittle martensitic structure. The steel is then tempered to reduce brittleness, a special type of annealing. In this application, the annealing (tempering) process transforms some of the martensite into cementite or spherulites, reducing internal stress and defects. The end result is a more ductile and fracture resistant steel.
Previous:Steel production process.
