Spring steel, thin-sheet pieces are loaded on the kontiniu furnaces and are treated differently from normal by automatic loading or manual sorting in order to prevent the parts from coming up. Accurate and homogeneous heat distribution in each zone of the oven heated by electric heating system. At the same time, the controlled atmosphere prevents smoothing in the treated parts, resulting in excellent surface quality and suitable hardness for each part.
The steel part is heated under protective gas to austenite phase temperature (mostly 810-900°C) and at this temperature it is hardened by being kept in oil for a certain time according to the part thickness. At the end of the hardening process, from the surface of a piece toward the core, the hardness of the steel depends on the hardenability of the steel, which depends on the chemical composition of the steel and on the grain structure.
Since the martensitic structure obtained after hardening is extremely hard and brittle, tempering is applied to give a sufficient structure to the material, to remove the stresses and to obtain the necessary surface hardness. Tempering is applied at varying temperatures (usually 150-650°C) depending on the desired hardness.