Water offers the most "severe" quench. It would normally extract the heat
from the steel the quickest. The metal will vaporize the water and form a
steam layer. Heat transfer is not so fast through the steam layer. On the
other hand the very act of transforming the water into steam means the water
has to take in enormous amounts of energy to transform the water from liquid
state to gaseous state (steam). Moving the part and recirculating the water
aids in getting the best quench.

With oil there is much less vapor formation of the oil. There might be a
little bubbling seen but nowhere as violent as with water. Therefore the
heat removal rate is slower.

There is another quench in between these two, which is polymer quenchants.
These offer a compromise.

The choice for quench mdeia depends on the steel grade being quenched, the
part geometry and some other factors like whether quenching is being done in
an atmospheric controlled integral-quench furnace, for example.

Mark


"Time Traveler" wrote in message
...
Looking at the posts on metal hardening I was wondering what are the
dynamics of oil versus water hardening.What is happening to the metal
using one or the other?I assume water brings down the temperature
quicker but have no empirical knowledge on the subject.