"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.

As others have said, you're right about that, and, depending on the alloy,
thickness, and temperature of the quenching bath, the water quench may well
give you a little more hardness.

In the case of plain-carbon steels, water will give you more hardness on all
but the thinnest pieces. But slower-quenching alloys, especially those that
collectively are called "oil hardening," may not harden any more with a
water quench. In fact, if the piece is more than 1/4" thick or so, all that
water will do is increase the risk that the piece will crack. Water may,
however, result in a *deeper*, if not a harder, hardened zone in that case.

As for what is happening to the metal, you'd do well to find a description
online or in a book. It involves a couple of phase-changes in the steel. The
phase changes are generally the same for carbon steel and common alloys, but
it's better absorbed from a description written by experts who have had the
time to re-write, and an editor.

--
Ed Huntress