Quench oil too hot?

R

R.C.Reichert

Joined
Jul 26, 2008
Messages
1,006
Hello,

I was just busy quenching some small hunting knife blanks I made out of 1080. I have a quench tank that holds about 4 litres of canola and I started out with a temperature of °120F. By the third blade, I checked the temperature after the quench and the canola and was sitting at °200F. All three blades hardened up really nice and straight. My concern is that I quenched that last knife in oil that was possibly too hot ~°150-°170F give or take maybe a little more. Is this going to have any detrimental effect on the blade, or will it still be okay?

Thanks!
 
I can't answer whether or not the effect of the heated oil is detrimental or not, but if you're using a vertical tube type tank, the oil on top usually is hotter and agitating in between helps keep it even.

Also, 4 liters really isn't enough, for the reason you've observed.
 
Only way to really tell is to check them all on a hardness tester of some sort.

If they all skate a file, I’d say “good enough” (unless I was planning on selling them) and make knives out of ‘em
 
I decided to just re-do them and wait 15-20 minutes between each blade to allow the oil to cool down. They all did skate and harden up very nicely though, but yes, I do plan on selling them, so I just wanted to be sure.
 
Here is a great trick:
Put a couple liter bottles of water in the freezer. Tie a string around each neck.When the oil climbs a bit, dunk a bottle up and down a bit to cool the oil.

The real answer is to make a tank that holds ten to 20 liters of oil.
 
weo said:
Just make sure you do this before the temp reaches the melting point of the bottle or cap....;)
Click to expand...

(I posted this yesterday, but for some reason it is still in the stored info.)
Actually, no. Until the bottle contents drop below 32F, the surface is 32F. This is why a pan of water on the stove with the burner on high will stay 32F until the very last shard of ice is gone.

Obviously, there is a limit to where thermal transfer is overpowered, but in the temperature range of a oil tank, the plastic won't melt.
 
You guys are right, Stacy and Natlek. Thanks for explaining to folks who thought I was actually saying this is a possibility. As I've been reviewing the stickies, I guess I caught a bit of Nick Wheeler's attitude and I was just injecting a little humor here (isn't that what the emogees are for?). I guess I should have known better.
 
I pretty much thought you were kidding, but on the internet anything is possible. Besides, I never pass up a chance to give a lecture on physics.*

To get back to the issue, three gallons is the minimum and 5 gallons is better for quenching blades. You will find that warp decreases as evenness of quenching goes up.


*I am giving a lecture this coming Wednesday at TCC, so if anyone local is wanting to learn about the telephone and the history of communications, shoot me a message and I'll give you the info. I'll have most all of my antique phone collection out for display and discussion after the lecture. Lecture is 10AM-2PM. Physics, anthropology, evolution, communications, etc. You can earn cool phrases to drop at cocktail parties, like "Modality Independent".
This is part of a series of lectures I will be giving over the fall and winter.
 
You must log in or register to reply here.
Back
Top