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Austempering

Austempering produces a good combination of the component properties of hardness and strength in steel materials and cast-iron.  In this heat treatment the component is austenised in the same way as in hardening, so the heat treatment is carried out at a temperature between 800 – 1050 °C, depending on material.

The treatment is mainly carried out in salt.  Quenching is carried out in a hot salt-bath.  The temperature of the hot salt-bath is dictated by the material and lies between 250 and 450 °C.  The component remains at a constant temperature in the salt-bath until the structural transformation from austenite to bainite (intermediate stage) is complete.  No martensite is formed! 

Depending on material the transformation can be completed in a few minutes, although sometimes it can take several hours.  Finally the component is cooled in air and may not be tempered further under any circumstances.

A typical use of austempering is for small, thin components, such as springs, nails and special knife blades, but also for large components of alloyed cast iron.

 

Suitable Materials

Typically components made of steels such as C45, C75, C67E, 42CrMo4,65Cr3, 67SiCr5, but also alloyed, bainitic cast-iron (ADI Material).

 

Advantages of Austempering

  • High strength
  • Maximum  ductility
  • Reduced distortion
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