Hehkutus

Hehkutus is a heat treatment process used in metallurgy to alter the properties of a material, most commonly metals, by heating to a specified temperature, maintaining that temperature for a period (soaking), and then cooling at a controlled rate. The primary goals are to relieve internal stresses, increase ductility, reduce hardness, and refine the microstructure to improve formability and machinability. The exact temperature and cooling profile depend on the material and the desired outcome.

During hehkutus, the environment inside the furnace can affect surface chemistry; protective atmospheres or vacuum may be used to minimize oxidation or decarburization. Variants include full annealing, process or recrystallization annealing, and isothermal or diffusion annealing. In steels, the process is often associated with transforming the microstructure to reduce hardness and restore malleability after deformation. In nonferrous metals such as aluminum or copper alloys, annealing is primarily used to soften the material and recover ductility after work hardening.

Common materials subjected to hehkutus include steel, aluminum alloys, and copper alloys, though the method applies to other metals and some ceramics. The resulting properties are sensitive to the cooling rate: slower cooling generally produces a softer, more ductile structure and more uniform properties, while faster cooling can preserve certain microstructural characteristics created during soaking.

Hehkutus has practical importance in manufacturing and engineering, serving to prepare materials for forming, reduce residual stresses from welding or machining, and improve consistency in subsequent processing. It is one of several controlled heat-treatment techniques used to tailor mechanical performance for specific applications.