Water or Oil quenching

This is what you said:
Kind of like oil, when you warm it up (to a point, 130F-140F max) you also thin it and it becomes a faster quench. Thicker fluids move slower and thus hold heat close to the blade longer.

I'm asking you if you believe that applies to water also
 
Water, I would have to say NO, warmer water would be more prone to steam pockets, no? However, it may be technically faster where the water is touching the steel.

What I said was in response to your thinking that more densely concentrated SALT BRINE would be a faster quench.
 
ok, so I'm reading this

http://mse.iastate.edu/solidification/Courses/MatE443-Website/labs/Lab3.pdf

Different quench media vary considerably with respect to their effectiveness in quenching. This is primarily due to their convective properties, and is quantified by the Grossman number (H), which expresses the ratio of heat transfer due to quenchant convection to that associated with diffusion from the steel to the quenchant. Higher Grossman number indicates more dominate convective transfer and a more effective quench. For this reason, the Grossman number is also known as the quench severity. Typical quench media Grossman numbers are shown below:

I can't cut and paste it, but according to the numbers they state, brine has the highest numbers, which means a faster heat transfer due to quenchant convection to that associated with diffusion from the steel to the quenchant?
 
The only faster quench than brine (which has a higher boiling point than water to begin with due to the sodium and chlorine ions in solution thus extracts more heat before phase change and as the water boils salt precipitate provides nucleation sites to cut down on the size of vapor pockets ) is brine with surfactant (called "superquench") as the surfactant breaks the surface tension of the vapor/fluid interface

My understanding is that superquench is so violent it will break W2

-Page
 
sunshadow said:
The only faster quench than brine (which has a higher boiling point than water to begin with due to the sodium and chlorine ions in solution thus extracts more heat before phase change and as the water boils salt precipitate provides nucleation sites to cut down on the size of vapor pockets ) is brine with surfactant (called "superquench") as the surfactant breaks the surface tension of the vapor/fluid interface

My understanding is that superquench is so violent it will break W2

-Page
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And it'll break most other steels over about 45 points of carbon.
 
Just for the record, when we say "brine" we are talking about the well documented and published solution of 5% - 10% NaCL solution, correct? And a more densely saturated solution is slower, if what I'm reading in the cited quotes is correct.
 
69_knives said:
Just for the record, when we say "brine" we are talking about the well documented and published solution of 5% - 10% NaCL solution, correct? And a more densely saturated solution is slower, if what I'm reading in the cited quotes is correct.
Click to expand...

That's the way I understand it. I use brine for quenching W-1. Again, the steel must not be overheated or it probably will crack.
 
K R Johnson said:
That's the way I understand it. I use brine for quenching W-1. Again, the steel must not be overheated or it probably will crack.
Click to expand...

It seems to me that even if you austenitize at 1525, you could still allow the steel to cool to perhaps 1400 and equalize before quenching. I doubt that things that are in solution are going to precipitate back out of solution at that temperature, and you'd have less shock going into a brine quench and less heat to extract (and thus a faster trip past the nose)?

I'm sure if this were a good idea, industry would be doing it. But for the life of me I don't know why it wouldn't work. Hum...
 
there is an old Austrian black smith here in Boise who told me that a solution of lye and water would make 1018/1020 hard enough to make a good punch or chisel. I tried a piece of 1018 cold finish and sure enough it would skate a file and was hard enough to break when I treid to bend to 90. I have no idea how hard it actually got but I believe it would have made a servicible blade. The steel was a little more than an 1/8th thick and about six or seven long. All scale was blown off the blade and the break was smooth and light gray with ano indication of large grain. Anyone have any imput to this?
 
Lye (sodium hydroxide) is a more severe quench than brine. I found this out when I first started using 1095 and couldn't find proper quench oil locally. We have thousands of liters of the solution at the shop and I thought what the heck, if salt brine works maybe sodium hydroxide will too. I quickly and severely cracked a couple of blades and haven't tried it since.

The "super quench" was invented as a safe alternative to sodium hydroxide as the fumes that come off of the stuff are not good for the respiratory system.
 
Rob Gunter was working at Sandia Labratory in Albuquerque when OSHA showed up and
made them quit using lye. He had to find an alternative which we now know as "Superquench".
 
I started to respond about lye quenchant, but decided to avoided the mention of lye because the risk is high, and it is corrosive as hell.
It is probably the most sever readily available quenchant, but the use on knife blades is not required.....and the safety is a real problem.


So, kids, don't try this at home. The factories that use lye are professionals, and they understand the risks.


Now if we want to digress into the theory of really strange quenchants, what about quenching in mercury???? ( Just kidding, don't do it !!!)

Stacy
 
I learned recently that industry used to quench certain alloys (most likely things like HSS) in molten lead. There's another one I wouldn't want to mess with.
 
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