In conventional austempering process, cast materials are held between 850-950 ° C temperature range for a sufficient period of time (usually 1-2 hours) in order to obtain a complete  austenite (γ) matrix. After that, fast cooled to 250-400 ° C temperature range  and kept for 1-4 hours at ed temperature then cooled to room temperature in air.



The main purpose of the austemperingheat treatmentis toobtaina bainiticmatrixstructure accompanied by high carbon austenite.




Advantages of Austempering:

•Less Distortion
•Greater Ductility
•Parts are platerfriendly due to the clean surface from the salt quench
•Uniform and consistent Hardness
•Tougher and More Wear Resistant
•Higher Impact and Fatigue Strengths
•Resistance to Hydrogen Embrittlement

Limitations of Austempering:

•Austemperingcan be applied to parts where the transformation to pearlitecan be avoided.

•This means that the section must be cooled fast enough to avoid the formation of pearlite. Thin sections can be cooled faster than the bulky sections.



DIN standard of ductile irons


EN 1564 standard of ADI 



  • Higher toughness
  • Higher wear resistance
  • Increase in fatigue strength
  • increase in hardness
  • Increase in tensile and yield strength



Applications of ADI