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Types of tempering

Tempering from outside-The cold workpiece is slowly heated by means of appropriate heat sources and after having reached the tempering temperature (between 200°C and 500°C) it is cooled down. 
Tempering from inside:The workpiece is shortly quenched after having been hardened so that only outer layer is cold. The residual heat penetrates from inside, after having reached the tempering temperature it is cooled down. The same effect can be reached when the workpiece is cooled down only on one side and the heat contained in the other part runs after again



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