quenching media ?

greetings o wise ones
i have a question about the different media used for quenching. as i sit here in the evenings i read a lot. haveing read a few books on
blacksmithing and noticed a difference. when discussing quenchants they all list oil as the slowest /least harsh, some then go to water others to brine, with the harshest flipping the water and brine. what is the consensus here as to order of severity of quench media? air - oil - water - brine or is it air - oil - brine - water.
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son_of snipped-for-privacy@yahoo.com wrote:

Air, oil, water, brine; slowest to fastest. What you use depends on what the work is made of. Some alloys will tolerate water and brine, others flat won't.
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son_of snipped-for-privacy@yahoo.com wrote:

Least harsh to most harsh: air, oil, water, brine. It has to do with the boiling points of the various media.
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Tom Stovall, CJF
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Alright so lets say that a higher boiling point has a slower cooling factor. That is what we're saying right? So on quote from Alexander Weyger's book The Complete Blacksmith, he lists water having a boiling point of 212 F, Brine at 226 F and Oil at 290 F. His claim is that because of this water is the fastest (and harshest). Makes sense to me but is it true? Seems like everybody I've heard from in the groups and forums believes it's the other way around for water and brine. Don't have a particular favorite here myself but I'd like to get straight answer on this one ;-) Granted there are offsets to the boiling points since water boils at different temperatures depending on the altitude (air pressure) but I would think the same holds true for brine and maybe oil too? Then there are a variety of oils in use as a quenching medium so not all oils will work the same (as other oils). Now other sources I've read (think it was Metallurgy Theory and Practice by Dell K. Allen) make the statement that when the quench boils it actually creates an insulating heat shield till the vapor blows off and so would cool less efficiently once that happens. Hey, I'm confused and thats after reading the work of the "experts". Might just be me though...
GA
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Pretty much all competent sources agree on brine being the fastest quench. As for why, think not "boiling point", think "heat capacity", or "specific heat". It takes more heat to heat up the same amount of brine rather than water. More heat for water than oil. Believe in boiling points? Grab a thermos full of liquid nitrogen and try to get a good quench in it - it's not how cold it is, it's how fast it takes the heat away.
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Greyangel wrote:

Just to add to the confusion I have a book ("what steel shall I use?") that makes a distinction about what temperature the quench material needs to be -- they talk about experiments involving quenching low-carbon steels in chilled brine, and you can certainly chill brine down to a lower temperature than plain old water.
And yes, the boiling point of a liquid is determined by the air pressure -- you can boil water at room temperature if the pressure is low enough. Lower the pressure even more and you can boil it until it freezes, then watch it sublimate away.
I suspect that there are a lot of factors beyond just boiling point that affect how quickly a quench medium can transport heat away from a piece -- just off the top of my head the boiling point, thermal capacity, thermal capacity of the medium _and_ it's vapor would all have an effect. Two of my references ("What steel should I use" and "Hardening", or "Hardening Tool Steels" by Linsay press) both make a point of saying that quench water must be clean and one of them ("Hardening") recommends throwing in a bit of lime if the water gets soapy -- I can't see how this would affect any of the qualities that I've dreamed up already, yet obviously _somebody_ believed it made a difference.
Standard disclaimer: This is all just book learning; I've only quenched one or two pieces in my life, so I can't claim to be anything resembling an expert (although I have annealed any number of drill bits without really meaning to :).
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Tim Wescott wrote:
[...]

I don't know why, but you can't cool, much less quench, hot iron in soapy water. In my world, shame on the apprentice who rinses off his soapy hands in the slack tub.
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Tom Stovall wrote:

Jack Andrews in "New Edge of the Anvil" refutes that statement. he lists a solution "... to be used with low carbon steels (no hight than 30 points). On a 1018 mild steel a tool quenched, at 1550 F, light cherry red, in this solution can reach a hardness of 43 to 45 Rochwell C."
the solution is 5 gal water 5 lbs. salt 32 oz. dawn dishwashing liquid (blue) 8 oz. shaklee basic "I" wetting agent.
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son_of snipped-for-privacy@yahoo.com wrote:

Refutes arse.
If you have any doubts, just wash your hands in GoJo or Ivory soap, rinse off in your slack tub, then try to quench a piece of hot iron in the water.
After you do, please post the results on this forum.
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I don't know what that mess mixed together will do. :/ It might do just as he sez. <shrug>
My tool steels book makes a big deal out of the "vapor stage" and how long it hangs on as to the timing and whether it will allow time for the formation of pearlite.
Tap water is quicker than distilled water and adding just 0.2% NaCl made water twice as fast. A "2% soap solution" could slow the distilled water by a factor of 4 which could keep the austenite from decomposing into almost no martensite under certain conditions.
9% solution of NaCl in water was considered the best overall concentration. If you insist;) on using NaOH then 3% is suggested as "optimum".
There's a lot more to this, we've barily scratched the surface. ;)
FWIW, I've had real good luck with commercial quenching oil on 1095 at ~1/32" thick. Beats the heck out of water or brine, IME.
Alvin in AZ
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snipped-for-privacy@XX.com wrote:

I don't know about GoJo, but Ivory soap is _soap_, made from fat and lye. Dawn dish washing detergent is detergent but not soap; it shares some qualities of soap, but isn't soap.
Perhaps it is specifically soap that causes the problem, or a class of detergents to which soap belongs, and not all detergents?
This would be a good science fair project if anyone has a 12-year old kid...
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GoJo is based on a "water soluble oil" (whatever that is;).

Cool idea. :)
Alvin in AZ
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snipped-for-privacy@XX.com wrote in
snip

I have a feeling it could be olive oil or some type of citrus oil, both water soluble.     On the subject that started this thread about the soap in the quench, I once had a lady offer to buy some of my quench water right out of the barrel at a show..She said her grandmother, and great grandmother both cured everything by rubbing the water from a blacksmith's quench tank, go figure...Heck if I'd known that to be true, well nevermind..
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On 6 Jan 2005 18:36:10 -0800, son_of snipped-for-privacy@yahoo.com wrote:

I've heard about the "soap problem" before, but never really investigated it. It's usually put down to some sort of localised foaming problem around the hot metal and a particularly dense layer of steam bubbles. As any text on boilers will tell you, conduction through the metal firebox and the water itself is quite efficient, it's the thin gas layers that represent the real barrier to heat, even though they're so thin.
In this Edge of the Anvil example though, there's a load of wetting agent added as well as the soap. This may well be there to reduce the bubble layer.
I can't think what the original intention of adding soap in the first place is though.
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son_of snipped-for-privacy@yahoo.com wrote:

This is commonly known as Super Quench. It works very nicely on medium or lower carbon steel. Tool steel, properly hardened and tempered is better, but you can get "mild" steel in a much larger variety of shapes.
Steve
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Steve Smith wrote:

I can use tool steel instead of Super Quench? Wow. So I listen for the "clank" instead of "sizzle" when I plunge my piece into the quench?
:)
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On Fri, 07 Jan 2005 17:45:11 -0800, Tim Wescott
<snipped>

Of course, surley you've heard of the sword in the anvil. How ya think it got there?
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Forger wrote:

If you can get it in there, its the fastest quench around!
Steve

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Steve Smith wrote:

I've heard of quenching being done by slapping thin stock between two copper plates. I still can't work out how you get the piece out of the oven and onto the plates smoothly, but it was being done in the 1930's.
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Now that brings up a good point. In order to harden a piece of steel you simply need to drop it through the nose curve in a short enough amount of time. Seems like really thin stuff would be darn near air hardening. I wouldn't think it would really be that difficult to stick thin stock knives between copper plates in the same time it takes to quench it and that should eliminate any warping.
GA
wrote:

quench?
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