Quench plates?

LightningSharp

LightningSharp

Member
Greetings,

I've read several posts where thick aluminum plates are used to quench air quenched steel such as D2. I was wondering if anyone had tried other materials, like marble or granite. I have some surfaced 2" thick slabs of granite that would fit just right in my press....

any ideas?

Lee Haag
 
The purpose of the thick aluminum plates keeps the steel straight and acts as a heat sink to suck the heat out rapidly verses still air. I use 2" thick pieces myself with blasts of compressed air. I'm not saying it won't work, but why mess with something that may ruin your heat treating process, forcing you to start over.

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Keep in mind that I'm just plain dumb when it comes to heat treating anything but high carbon steels, and at best a rookie with those, but...

From EngineeringToolbox.com:
“Thermal conductivity can be defined as the quantity of heat transmitted through a unit thickness of a material, under steady state conditions"
So...Thermal conductivity describes a material's ability to conduct heat.
Thermal conductivity is measured in W/(mK) in the SI system, and in BTUs in the Imperial system.
At25 degrees celsius, Aluminum rates at 205 W/(mK).
At the same temperature, Granite rates at only 1.7 t0 4.0 W/(mK).


I couldn't find any thermal conductivity ratings for the materials at higher temperatures, but
I would think that even at typical heat treat temperatures, granite would not be nearly effective as aluminum as a quench plate.

Bill
 
Where is a good place to get quench plates. What exactly am I looking for?


Mark Huston

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Depends on size of your blades - for smaller 1/8" thick and less blades a 3/4"X3"X12" will work just fine, but if your blades are longer you might need something 15" or so long. If your blades are mostly 3/16" and thicker you'll need more heatsink with perhaps a 1"X4"X16" or so? Some folks night chose a set of each size so you don't have to handle that big set when you are doing paring, steak, etc type knives, or even smaller chef knives the 3/4"X3" wide will provide plenty of heatsink. If I think my blade is pushing I'll mist the plates with water to provide faster cooling. Remember, many of the stainless steels (Sandvik for one) only require to get below 1100ºF in 2 minutes time for full heat treat.

Here are a couple of items you might wish to look at, depending on amount of money you wish to spend.

http://usaknifemaker.com/quench-plates-pair-aluminum-1-x4-x12.html (Owner of this site is always a good place to deal with.)

http://www.industrialmetalsales.com/3-4-Thick_c71.htm (selection of 3/4" plates)

http://www.industrialmetalsales.com/1-Thick_c73.htm (selection of 1" plates)
 
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If you have a friendly scrap yard to "shop" in, you can often find cut off aluminum. Those days are about gone as the lawyers have closed walking around access for liability reasons.

most any flat 1" (3/4" minimum, it can be thicker but not thinner) Aluminum will work. Make it long and wide enough by an extra inch or two of your blade.
Copper would work better as a faster heat conductor but would be stupidly expensive and heavy. I have seen copper plates and I have seen copper lined aluminum plates so they do exist. In both cases, they came from a scrap pile.

Shoot compressed air in between the plates during quench to help cool things down.
 
Just asking this more out of curiosity than anything, as I am a really long way from trying to HT my own air-cool steel.
But anyhow... I have a bunch of 1/8 - 3/16 aluminum plate that I could easily stack/layer it to about 1". Would that work, or would the layering cause wierd expansion as it heatsinks, and possibly even actually cause a blade to warp?
 
I got my quench plates from a metal supplier on eBay. Mine are 1"x6"x12" aluminum and they've worked great. I paid $20 each with free shipping. Be patient and you can get a good deal.
 
I have a bunch of 1/8 - 3/16 aluminum plate that I could easily stack/layer it to about 1". Would that work, or would the layering cause wierd expansion as it heatsinks, and possibly even actually cause a blade to warp?
Click to expand...

Early on in my career, I tried stacking thinner aluminum plates....I found it counterproductive in that it seemed to hold more heat then it "sucked" away. Later on, after gaining some knowledge and experience I understood that it was actually the airspace (although it was a tiny airspace) between the thinner plates that acted as an insulator, preventing the heat from flowing to the next plate.

Long story short, do an Boss recommends....nothing less then a solid 3/4" thickness. Personally I have 1" X 12" X 12" plates that I stumbled across at the old Boeing Surplus store in WA. That was 10+ years ago, and the "$10 each" is still on them. :)
 
Cheapskate thinking, tig all the small plates together to form the needed larger plate. Is just my cheap arsed .02 worth
 
IMG_0425.jpgIMG_0426.jpgThese are from an Aluminum bar I bought at my local scrapyard 3''X3''x20'' each , it always pay's to ask around.
 
EdCaffreyMS said:
Early on in my career, I tried stacking thinner aluminum plates....I found it counterproductive in that it seemed to hold more heat then it "sucked" away. Later on, after gaining some knowledge and experience I understood that it was actually the airspace (although it was a tiny airspace) between the thinner plates that acted as an insulator, preventing the heat from flowing to the next plate.

Long story short, do an Boss recommends....nothing less then a solid 3/4" thickness. Personally I have 1" X 12" X 12" plates that I stumbled across at the old Boeing Surplus store in WA. That was 10+ years ago, and the "$10 each" is still on them. :)
Click to expand...
Thanks for the info! Like I said, I'm a very long way from doing HT on air quenching steels, but the thought came that the thinner sheets I have might potentially be useful in that way. Now I'll just have to find another use for them Not like I had a specific use in mind when I salvaged them from wherever I got em.
 
i use aluminum quench plates when working with thin O1(3/64" and 1/32"). two or three seconds in warm oil, then between 2 chilled 1/2" aluminum plates(1/2" cause they were free). works wonders. ebay or local scrap yard is probably best bet.
 
Dumb question. Do you clamp the blank between the plates or just use gravity. I would thing that pressure would help eliminate the gals Ed was commenting on in this earlier post.


Mark Huston

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I just press down on them with hand pressure. But, if you don't mind, I'd like to tack on another question. I just ht'd my first tapered tang Monday. It has a distal taper in both directions with the thickest point being the ricasso. When I put it in the quench plates, I kept them tilted toward the blade end since both ends can't be in contact. Is that what everybody else does? Seemed weird, like I wasn't getting enough contact anywhere on the blade.
 
I've had the same question. I've left a bit of a flat on my full grind knives, not taking the grind all the way up. I figured it would give more surface area to speed cooling and help keep the blade straight. Made me wonder how other people tackle this and if anyone has noticed a difference.
 
When dealing with tappered tangs I do my heat treat first.I usually do most grinding post heat treat anyway.I also put my plates on my big drill press and run the quill down for some pressure and shoot some air in around them.
 
I use a C-clamp to clamp my quench plates tight against blade - that helps prevent warping. On distal taper, I'd clamp on the blade so the tang portion would be the part not touching. As Boss said, blow air between plates, OR - perhaps mist a bit of water between (or on) plates to help with sucking heat from blade.

Ken H>
 
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