quenching media ?

Have the copper plates in a wood vise. (or wood lined) Have a three sided box in sorts - two of copper - the bottom being whatever and under the copper. The copper is 'attached'
to the wood plates so they don't fall. Take out the blank from the oven and place it top edge down and turn the handle.
The knife could be carried in a 'quiver' of insulation if the vise is far away.
That is an idea - just an idea, but one never knows.
Martin
Greyangel wrote:

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Martin Eastburn, Barbara Eastburn
@ home at Lion's Lair with our computer snipped-for-privacy@pacbell.net
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Greyangel wrote:

you
amount of

I
knives
should
which begs some questions.
how thin would the knife have to be to quench between copper plates?
how thick would the copper have to be?
would chilling the plates help or cause problems?
would other types of metal plates work?
are these questions worth anything (i.e. will someone try this) or are they just theoritical?
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Nothing wrong with theoretical. For instance, I'm mostly interested big blades with non flat geometry. No good to me at all. On the other hand if later I decide to make a small folder knife where I need a precisely flat blade then this could be quite handy... :-)
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Industry uses air hardening steels and/or "make it too big and finish grinding to size after heat treatment".
Alvin in AZ (read that in more than one ASM book;) ps- I am ASM's number-one newsgroup parrot :)
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Industry uses that method sometimes. :) Betcha it's an expensive and carefully machined set up tho. :/
IMO, it ain't worth messing with because the warps can be straightened out, right after the quench.
I consider it part of the quenching process.
All the austenite doesn't decompose to martensite all at once, when first pulled from the quench tank the steel is mostly still soft (austenite) over the next few seconds it changes over so you have time to straighten it out.
I use clunky old line-pliers. ;)
It's tricky as anything for me, but I can see a guy getting really good at it. Yes, the dangged stuff is constantly changing... its stiffness and its elastic limit are both changing quickly, but only in one direction, and I believe at a predictable rate, something that can be counted on? If so, that's your foot-in-the-door.
I've failed to get a few longer blades right, but off-hand I don't think I've made any worse than if I'd left 'em as-is.
Those were 1095 too, something with a little Cr in it should be slower to transform, so allowing more time?
It's tricky, but so is riding a bicycle, just need more experience IMO and it could become second nature too?
Another reason I don't like the quenching between plates idea is you'd need at least an oil hardening steel to make up for the non-contact points (it isn't going to mate perfectly)... :/
A need for air hardening steel sounds more like it now huh? ;) Air hardening steel won't need plates to keep it straight. ;) Is that a Catch 22? :)
Part of my problem with fixing -all- my warped blades is I heat treat at night. :/ YMMV (your mileage will be better ;) since you won't be using line pliers and it won't be so stinkin dark either. ;)
Another thing is, I heat treat a batch like 1 to 3 times a year, I don't see myself ever getting real-good at taking advantage of this property.
I betcha most old time blacksmiths were friggin good at taking advantage of that property tho! Don't you think so too? :)
What do you think? :)
Alvin in AZ
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Hmmm - I think next time I set out to quench a blade I'm gonna keep my anvil handy along with my industrial strength flatter ;-) Got the piece of the railroad rail that I cut off the underside of my anvil. Basically the foot and webbing of the rail about 8 inches long. Keep it around to smack down on hot iron to surface level and straighten. Think if I just press a blade right out of the quench it will hold straight after a few seconds of further cooling? One of the things I did wrong with the last blade was to take it all the way to *cold* in the quench. Should have got it into the oven while it was still good and warm. I found a couple of small fractures in the edge later.
Yeah, a cooling press for a quench is probably not gonna be too dependable unless you're talking about really flat thin stuff.
GA

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wrote:

Hello everyone, I was just wondering. What would be the suspected results if I were to quench, in the mixture above, a blade made from a plain high carbon steel, such as one made from an old file?
Also, what effect would adding a bag of ice to the mix be?
Bear
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Bear wrote:

Superquench is only useful for 40-50 points of carbon and below. If you put the above blade in, it would crack or shatter in the quench. Way too fast for real tool steel.
Steve
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On Thu, 6 Jan 2005 16:25:23 -0800, "Greyangel"

Why ? That's a pretty clueless book, especially on heat treatment.
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Greyangel wrote:

Here is an email I saved from TheForge. I save many of Hochewa's posts.
Steve
---------------------------
To All, Quenchants are to extract heat from the work piece at somewhat of a controlled rate. The traditionally meanest, fastest, ugliest quench was sodium hydroxide (lye) in water to the tune of about 10% by weight. Lye is dangerous as it will chew on your skin, eyes and lungs.
The action of the sodium is reportedly to reduce the solubility of air in the water. Less air, more water better quench.
The action of the salt is to deposit itself on the work piece as the water evaporates around the work. The resulting steam blanket is a poor quench medium. The salt that precipitates onto the surface has some water of hydration in it. As it heats, it turns to steam rapidly (I want to say explosively here but it is not an explosion). This burst of steam breaks down the steam blanket surrounding the work and fresh quench is brought to the surface. The process repeats itself until the work is below 212*F. This is the sizzle that you hear. The formation of steam on the surface of the work extracts a most of the heat. The water does not do much until the work is cool enough that you are not making steam. Then the water cools by conduction.
Common salt in water to the tune of 10% by weight works exactly the same way, almost as well and is a lot safer. The old timers say the brine should be strong enough to float a potato. More salt is not better.
Plain water is not a good quenchant as the chemistry of it is variable. Just imagine what has lived or died or fallen into your slack tub.
MIneral oils can be had in a variety of quench rates. Synthetic quenchants are glycol based and can mirror the mineral oils without the flamability worrys. Motor oils are usually too thick to be effective but they can be used in a pinch.
Gunter's Super Quench is an attempt to maximize the quench rate without the hazards of lye. The principles are the same. The major difference is that the SQ contains surfactants and detergents which are wetting agents. It still contains water and salt. The wetting agents probably do the most good as the work cools to below the flash point of water.
Given all of the above, why do you have to worry about quench rates?
A full explanation of a TTT-Curve is beyond my patience at this point in time. A brief summary follows:
The ttt curve is shaped like a C. The y axis is temperature and the x axis is time. The nose of the C is at or about 1200*f or so. The distance between the y axis at t=0 and the nose of the curve is determined by the alloy content of the work. This also determines the quench. If you go through the nose of the curve you make pearlite. Miss the nose and you have a shot at martensite. For a 1% plain carbon steel like W-1, the distance between the nose of the curve and the y axis is about 1-2 seconds. This means that you must take the work from 1575*F of so to 1200*F in less than 2 seconds. This is why you use brine and this is why it only hardens to a limited depth. For A-2 this time is about 2-3 hours. A-2 is air-hardening. It also hardens all the way through.
Hardening does not occur until you cool the piece to around 400*F. But then this is another story.....
Regards,
Hochewa
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