salt bath carburizing

The parts that are going to be carburized are placed in molten salts an are treated at temperatures – quite similar to the treatment in furnaces – at around 850 to 950 °C. The targeted carburization depth is rather low and below 0,5 mm. Therefore, process times are usually short. By constantly monitoring the concentrations of potassium cyanide and potassium cyanate the process remains stable and reproducibility is guaranteed.

After the carburizing the workpieces are usually quenched in another salt bath at lower temperatures between 160 and 200 °C.  Again, the advantage of using molten salt is a very high uniformity of the quench effect on the workpiece without any kind of vapor bubbles. To finish the process, the parts are then treated in a tempering furnace to relieve stresses in the material structure and to reduce sensitivity to grinding cracks.