Heated vs. ambient temperature oil quench

[Michael Bennett]

I'm hardening a mixture of steels in my knifemaking venture. I've got stock 1095, but also have some mystery steels - leaf spring/mower blade stuff. I'm quenching blades about 2.5"-4" long, 1" wide and 1/8" to 3/16" thick, but plan on doing longer blades in the future.

My quench oil is corn oil. How important is heating the oil prior to quench?

Thanks!

Mike

 

[Bruce Evans]

You do really need to heat the oil some before quenching,It just seem to work better....It isn't that hard,I just heat a rod in my forge then put it in the oil and that is usually enough.It all depends on how much oil you are using and what the temperature of the oil is before you heat it.I use two rods in the winter time and one in teh summer when it is already hot in teh smithy....
Hope this helps some,
Bruce

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Bruce Evans Handcrafted Knives
The soul of the Knife begins in the Fire!!!!!
Member of,AKTI#A000223 and The American Bladesmith Society

 

[lively]

Im using automatic transmission fluid and I don't preheat it. I live outside of Tucson so it never really gets cold here and the ATF is thinner than oil already so I don't think it needs it.

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http://www.livelyknives.com

[This message has been edited by lively (edited 05-04-2001).]

 

[Allen Blade Knives]

Hello,

Yes heat your oil mixture to approx 130 to 135 degrees. The reasons are the following :

1: decreases chance of thermal shock which
could produce hairline fractures and
warpage, although uneven grinding also
does this.

2: actually cools the blade to under its
critical Temp faster in warm Oil due to
the fact that with room temp oil there
is a temdency for the cool oil to form
a vapor pocket around the hot blade when
quenched thus slowing the cooling process.

hope this helps, and to be sure of oil temp its best to use a candy thermometer
or liquid thermocoupler gauge.

Allen

 

[Michael Bennett]

Thanks all!

Mike