It is a process of eliminating the tension of a heat-treated steel by cooling it at a suitable speed by heating homogeneously under the transformation temperature and non-high temperatures (150-650°C), removing its fragility and brittleness.
Tempering is done for two purposes in a watered steel;
- To eliminate the tensions from cooling and transformation at the end of watering
- To increase the intensity and strength of the martensitic structure that steel has.
Furnaces with a current (circulation) in their atmosphere are ideal for this job. Since there is a certain relationship between steel hardness and tensile strength, steel subjected to tempering can be tempered to the desired tensile strength.
The properties provided by the tempering process can be summarized as follows:
Watered and tempered steels, with the same hardness, generally have almost the same tensile strength. Steels with the same carbon content and a completely martensitic structure gain the same hardness and tensile strength in the case of watering. Different alloying element steels with carbon in the same range get different hardness and tensile strength.