Got a blacksmithing question

Just another way to cool the metal, from what I can rustle up on google, water vs. oil appears based on preference in that industry.

Quenching hardens steel so it holds an edge. Oil quenching is more forgiving than water. Water tends to craze the metal.

From Quora.com

Precisely what you quench the steel in is largely determined by what the alloy of the steel is. Most wrought iron and many alloys of carbon steel can be quenched in water. Some alloys will be better quenched in brine, which will cool them somewhat more slowly. Oil is less conductive of heat, and is somewhat slower acting. There are certain alloys that are actually to be quenched by air, which is probably as slow as you get, though sometimes I understand that sand is used. Anything other than water is generally used with the idea that a failure is less likely to occur. 'Failure' usually means a crack or breakage of the hardened steel.

I believe that the oil is thought to transfer some carbon to the steel, aiding in the hardening and subsequent tempering.

RADAR, post: 440887, member: 413 wrote: Precisely what you quench the steel in is largely determined by what the alloy of the steel is.

In fact, some alloys are known as "oil quench" steel. I have an 18" length of 3/4" square oil quench bar that I used to make a special-purpose punch. I have a gallon can of quench oil that I keep around for the purpose.

Just A. Surveyor, post: 440881, member: 12855 wrote: I see smith's sometimes quench in oil and and am puzzled why they would put hot steel in oil.

Anyone know why?

It's a way of cooling the oil and adding temper for strength. Water does not work the same way. You can take temper out of, or add to steel with heat and oil/water.

Oil quench usually hardens teh steel.
Water quench, if done improperly will crystallize that steel and make it hard, but brittle.

Watch this show. Good nothing on, interesting kind of show:
http://www.history.com/shows/forged-in-fire