Offers the best possible toughness and high hardness.
Austempering is used if special properties are required, such as the best possible toughness at high hardness. During this heat treatment, (the so-called bainitizing or bainitic quenching and tempering), the component is austenitized in the same way as during hardening.
Austenitizing – steel parts are heated up to a temperature that depend on the material. This changes the structure to austenite.
The quenching of the steel parts takes place in a hot salt bath. The temperature of the hot salt bath depends on the desired hardness. The component remains in the salt bath at a constant temperature (isothermal hardening) until the structural transformation from austenite to bainite is completed. No martensite is formed in the process. The transformation time depends on the used material and the thickness of the material. Afterwards the component will be cooled in air.
ADVANTAGES OF THE AUSTEMPERING TREATMENT
Very high toughness is combined with high hardness
Hardening distortion is minimized, especially with low material thickness
Increase of the fatigue strength compared to oil tempering
Reduction of wear and tear
Increase of insensitivity to hydrogen embrittlement during subsequent coating
Suitable materials for austempering (bainitizing):
all tempered steels, e.g. 20MnB4, C45, C75, C67E, 42CrMo4, 65Cr3, 67SiCr5, 100Cr6…