Quenching is not a new process and has been used in metalworking since very early recorded time. It is most often associated in history with blacksmithing but was a standard process used in Europe in the 15th century.
In the earliest processes, water was used as the quenching agent. Today, quenching processes are much more specific and controlled. This includes the uniform heating of the piece, the coaching of the piece in an air furnace, a vacuum or in a prepared liquid followed by the use of a quenching liquid to quickly cool the workpiece.
Each of the stages in the quenching heat treatment process is carefully monitored. This includes a range of selection as to the heat, the uniform holding of the workpiece at the specific temperature and the choice of the quenching method.
Options to Consider
The choice of the quenching heat treatment method depends on the specific characteristics desired. Typically, quenching is used to create a hardened surface that is extremely resistant to wear. In some cases, the part or component may then go through a tempering process that reduces the brittleness the heating and the sudden cooling of the quenching heat treatment creates.
The liquids used in the cooling process of quenching have an impact on the hardening. Water is often used when there is a need for a significant level of hardness. Mineral oil can also be used, but it creates a slightly softer surface than water quenching due to the lower efficiency of the oil to cool the surface.
It is also possible to use specialized types of quenching methods. This can include inert gases, and most commonly nitrogen. Argon and helium can also be used, with the different gases selected based on the process and the desired end results with regards to surface hardness.
