Heat treatment is a metal material placed within the certain medium heat, heat preservation, cooling, by changing the material surface or internal microscopic structure, to control the performance of a metal hot working process.
Metal heat treatment is one of the important technologies in mechanical manufacturing, compared with other processing technology, heat treatment generally does not change the shape and the overall chemical composition of the work piece, but by changing the work piece internal microstructure, or change work piece surface chemical composition, gift or improve work piece using performance.
Take cutting tool – heat treatment for example, drill production process is: raw material – forging – heat treatment (annealing) – mechanical processing – heat treatment (quenching and tempering) – finishing (grinding). Drill raw material is high speed steel, because high speed steel with high intensity, good thermoplastic, strong commonality.
Drill (high speed steel) forge, its aim is not just change the shape and size of the steel, more important is through repeated upsetting swaging, broken carbide, improve carbide inhomogeneity make the steel chemical composition is more uniformity.
Drill (high speed steel) annealing, its purpose is to reduce the hardness, easy to machining, eliminate forging stress and is ready for subsequent mechanical processing, quenching organization.
Drill (high speed steel) quenching and tempering, right after correct quenching and tempering obtained its requested hardness, strength, hot hardness and wear resistance through, so quenching and tempering process decided on cutting tool using performance and life, is the key to the heat treatment.
Drill (high speed steel) tempering, quenching after high speed steel during tempering can produce obvious secondary hardening phenomenon, steel hardness and hot hardness have a direct impact.