The process of thorough hardening consists of combination of hardening and high tempering.
Depending on the cooling medium used, we have the following technologies:
– under protective atmosphere with oil quenching
– in a vacuum atmosphere with gas quenching (max 25 bar abs)
High tempering processes are carried out in a protective or nitrogen atmosphere.
We can distinguish typical, gradual, isothermal, surface finish hardening. Depending on the type of hardening, the steel microstructure is martensite or bainite.
The annealing process involves heating the material to a predetermined temperature, soaking at this temperature and slow cooling under a protective atmosphere or in air. Depending on the process parameters, we can distinguish between homogenizing, complete, normalizing, spheroidizing, recrystallizing and stress relieving annealing.
In the scope of annealing, we offer annealing with:
– slow cooling in a protective atmosphere
– slow cool in air atmosphere
– slow cool under vacuum
– slow or forced cool under nitrogen or argon
Tempering is a heat treatment process consisting in heating the previously hardened steel to a certain temperature, withstanding and slow air cooling. The purpose of tempering is to remove the stresses created during hardening, to change the physical properties and, above all, to increase impact resistance at the expense of reduced hardness.
We can distinguish three types of tempering:
– Low tempering at 150-250°C, applied in order to reduce hardening stresses. It does not significantly influence hardness reduction.
– Average tempering at 250-450°C, applied in order to provide significant strength and elasticity while maintaining sufficient resilience and ductility.
– High tempering at 450-Ac1, applied in order to significantly reduce hardness and obtain good flexural properties.