Quenching is rapid cooling (to avoid undesirable transformations) following pre-established heating. There are different cooling mediums such as water, brine (salt & water mix), oils, polymer based mixes and gases, air nitrogen or other.

When the work has cooled to approximately 125°F/50°C, (uncomfortable to touch) it is time to move on, without delay, to the next step, tempering, which is mandatory

Tempering is an operation consisting of heating, once or several times, the work to reduce the amount of stresses caused by the quenching operation. It also serves to adjust the hardness level and so obtain a certain measure of ductility/toughness.