A few questions?

Wally76

Member
Hey folks,

I have been making knives for about a year-and-a-half and have come across some discrepancies that I'm wondering if you guys could help clear up for me. I read today that quenching 1095 steel using canola oil would work for blades up to 1/8". I have been using 1095 in 5/32" and quenching in vegetable oil or canola oil and am wondering if this is okay.

Secondly I'm wondering about the difference between tempering one time versus tempering twice for the 1095. I have been doing it twice but again I have recently read that some only temper once.

And lastly I was wondering about the use of dry ice for D2 steel. Some of the literature I've been reading states 1 hour submersion with dry ice is sufficient and I hear 6 - 10 hours in another source and yet another states that dry ice won't work at all that it has to be liquid nitrogen.

Thank you for any help or suggestions you have!
 
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The best way to understand the hardenable thickness for your quenchant is to picture a wedge (like a blade bevel that has been cross sectioned), let’s say the wedge is ¼” at the spine and only 1/16” at the edge. When you quench into various speed oils you will get hardening to a given depth for that oil. When folks say that you will harden to 1/8”, what you will see is on the cross section the point at which the wedge is 1/8” thick is where you will start to get mixed microstructures of hardened and non-hardened steel. Below this point it will be all hard phases and at this point and above you will have mixtures until near the spine it will be all soft phases.

On an actual knife blade this will normally manifest itself in a hardening line, or hamon like feature perhaps half way up the blade. The edge is probably full hardness but a certain amount of the body of the blade did not harden fully, that which is over 1/8” thick.

Whether this is acceptable is up to you. The edge will perform well but you will give up strength for ductility toward the spine. Some people don’t mind this, others don’t like it. It is your call.
Tempering is normally recommended in one 2 hour sequence by much of the industrial literature, however there are some advantages in two 1 hour cycles with a cool to room temp between for folks who want to put in that extra effort.
 
Thank you for your reply Mr Cashen!
By switching to a true quench oil or motor oil, will that harden the entire blade then?
 
Thank you for your reply Mr Cashen!
By switching to a true quench oil or motor oil, will that harden the entire blade then?

On the true quench oil, yes... depending on the oil. Proper quench oils are designed for different cooling speeds and cooling curves. Most oils are engineered for medium speed (11-14 seconds) because that is what alloy steel and oil hardening steels were designed for as well. Old style simple steels that survive from the days when water based quenchants were used need a faster oil (7-10 second) to fully harden.

Dump the idea of motor oil altogether, it is designed for lubrication not cooling curves, is fraught with health hazard considerations, and will be a step backward from your current vegetable based options.
 
I have been reading your "Heat Treating Toolbox" and my head is spinning with the all the great information. It appears I will be purchasing some oil in the future. Thank you for all of your help! It is very much appreciated. Have a great night.
 
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