Heat treatment


  • The heat treatment is used to restore the alloy metallurgical structure to obtain optimal magnetic properties (this structure is destroyed during the various laminations)
  •  To do this, the heat treatment acts in three ways:
        - It removes all impurities (carbide, sulfide, nitrides) without      adding oxidation
        - It increases the grains size
        - It fixes the crystal structure


  • Both solutions are quite good and give excellent results although laboratory tests give an advantage to treatment with hydrogen.
  • Industrially, this is more or less the case because the results depend on:
            - The quality of the vacuum
            - The quality of the gas injected into the furnace and in particular the dew
               point  throughout the cycle
             - The cycle time and the regulation of the cooling.



  • The rising temperature
    It does not matter much, the time is related to the load in the oven and the thickness of the pieces.
  • Temperature and duration:
    In this step, the material rejects impurities and the grains grow.
         The longer the duration and the higher the temperature, the greater the permeability will be.
         Typically temperatures range from 1050 to 1175 ° C and the duration ranges from 1 to 6 hours.
  • The cooling
    It is especially important to manage the period between 600 ° and 300 ° because this is the phase when the interatomic sizes are fixed.


  • For many years, MMc has created different standards of heat treatment cycles in order to respond to:
             - Cost targets
             - Performance goals
  • These standards cycles are:
             - Industrial cycle where we try to attain permeability at low cost
             - Mid-range cycle where we seek a balance between cost and performance
             - High-end cycle where we aim to maximize the permeability of the material