plate quench question

Barry Clodfelter

Barry Clodfelter

Joined
May 29, 2007
Messages
571
I'm wondering about the aluminum used for plate quenching. I am researching it and see there are several grades that could be had. It looks like 6061 is the cheapest and available in the widest assortment of sizes. If I were wanting to do a plate quench on a air hardened steel blade roughly 1.25" x 11" x 3/16".

Are there any kind of guide lines on the sizes of plates that are used for this?

Would the aluminum retain enough heat that I would need a set for every blade in a heat treating run?
 
The thicker the better. You need enough mass to quench the blade faster. 1" is a good size for thicker blades. Al plates take heat and it wont quench fast enough if they get too hot. It is better to cool the plates to room temp before the second quench. I pour some cold water on plates before quenching the next knife. Be sure to wipe them dry of course...
 
I use 1" thick plates. I just heat treated 7 blades. They were all CPM D2. I quenched them one after the other, with only a few minutes in between. I did blow some air on them from my air compressor while in the plates. The plates were pretty hot by the last knife. I tempered them at 500F for 2 hours twice. All of them tested out at 60 on C scale. The most I do is 6 or 7 blades at a time. Hope that helps.
-John
 
So I should be good with 1" x 3" x 15" plates for quenching around 11" blades or would I need to have them longer or wider or both?
 
That should work fine, I put mine in a water bucket after a couple of blades to make sure they are cool. You need to work out how you are going to clamp them, I use some large wood clamps and clamp to edge of the bench.

I doubt there is much difference in the heat tranfer for different alloys, most of the alloying compounds are added in small quanities and should not make much difference, I think my plates are 6061 for the same reason cheap and alot of it around.
 
madness522 said:
So I should be good with 1" x 3" x 15" plates for quenching around 11" blades or would I need to have them longer or wider or both?
Click to expand...

Mine is about the same size. It is working very good.
Hints: 1 : Try to polish the inside of the plates. I quickens the heat absorption ability of the plate.
2: Wipe the plate inner sides clean before each quench with some dilluted alcohol or windex. The burned ss foil dust left from the previous quench or any other residue left on, blocks the contact.
3: Try to install the plates between shop vise jaws, it will ease the quenching process a lot.
4: As far as I inspected to blow some pressure air between the plates really improves the stainless grade steels and half-stainless steels (like D2) a bit. I've tested some D2 samples, the ones quenched without pressured air were a little bit more prone to oxidation and acids...

I hope I could help. Good luck...

Edit: hit # 5: For thinner and tapered blades try to press the plates in an instant: If the blade fist put to the bottom plate and later the upper plate pressed the thin edges of the blade may tend to bend down...
 
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Here's my set up. Plates are 1" thick 6" X 16".
-John
heattreatfangs008.jpg
 
Thanks guys! John your pic gave me a little inspiration! I bought a Wilton vise like that one on closeout at Lowe's and never got around to mounting it on my work bench. With a 6" width have you tried to quench more than one at a time? Or would that be more heat than the aluminum could transfer effectively?
 
I've done two at a time on my 6-8" plates with no problems. You do have to be careful
to quickly lay the foil packages out so that they don't overlap.

On the other hand I'm thinking about Emre's point # 5 above. I have seen this drooping
on blades that get thinner towards the tip but never thought the time difference
between contacting the plates on each side would be the cause of it. May need to
rethink how I've been doing things because of that. This may rule out multiple blades
at once if they have noticeable distal taper.
 
ok i guys i got some pretty dumb newbie questions if you dont mind.

1st. do you leave the blades in the foil?

2nd i understand that these types of steels usually have a longer soak time, but if using a controlled forge lets say it is a problem not to have them in foil?

3rd. i saw where some one was talking about using air from an air compressor. do you blow that inbetween the plates while cooling? or blow it on the plates to help keep the plates cool?

4. i understand clamping to keep the plates together but does the quenching process it's self need to have much pressue... does it need the kind of pressue a vise would give?

hope its not too many dumb questions

thanks

jake
 
1. Yes
2. The foil prevents scale by not letting any oxygen into the foil packet. I've only used it for Stainless Steels, and CPMD2.
3. Try to blow it in between the plates where the knife is. You don't have to do this.
4. The vise just makes things easier to handle. You do need some pressure though. You could just stand on the plates. This also helps prevent warpage.
-John
 
Keep in mind that if your grinding is uneven from side to side, you could end up with a blade that warps from left to right or right to left when it's laying flat. (ask me how I know :D)

Also when quenching blades that are very thin say 1/16" thick, the crimps on the foil packet will be likely thicker than the stock itself which could prevent complete contact between the plates and result in a warp (which can easily be fixed with a vise and some good eyes !)

Plate quenching does not guarantee you'll end up with straight knives. If the warp was there prior, chances are it will still be there after the quench.
 
Please allow me to add a bit more.

Some steel, like CPM154 ATS34 is really an oil quench that we can plate quench because knives are thin. But your aluminum needs to fit well for good contact. I recommend drops in the corners to keep things level and a dry run.

Some steel like D2 will achieve full hardness to a depth of something like 6" so long as it gets under 900 deg in something like 7 minutes (I'm pulling these numbers from my head, which is foggy tonight due to medication for my back, so take with a grain of salt). So it really isn't that critical.

D2 and A2 don't even need aluminum - steel is orders of magnitude faster than "fast enough". However - stainless (and D2) can improve corrosion resistance if quenched faster than air quench. It prevents the carbon from tying up all the chrome on the way down.

All these steels can be pulled from the plates after about 10 seconds, pulled from the foil, and tweaked with gloved hands. It is soft as puddy until it gets under 400.

I think most all these air quench steels benefit from cryo, unless you're making something that needs to withstand impact. It has been my experience that cryo works best when used as a part of the quench. For a serious cutter at high hardness I'd go from the plates to water to dry ice. LN is more convenient but not hugely different, IMO.
 
so A2 doesnt need the plates? then what do you do just take it our of the oven and let it sit and cool to room temp?

thanks

jake
 
strahd71 said:
so A2 doesnt need the plates? then what do you do just take it our of the oven and let it sit and cool to room temp?
Click to expand...

You can. In that case it's probably better to stand it on the spine and probably better to take it out of the delightfully 1700+ degree foil wrap. I'm not sure that either of these is necessary though -- haven't tried.
 
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more or less yes
forced air or strong breeze will help on larger thicknesses

BTW i have tested O1 in plate quench for my kitchen knives and have found it no problem to get 62 after temperign on a Al plate quench (that's 3/32 thick steel tho and no bevels cut for max plate to blade touching )


strahd71 said:
so A2 doesnt need the plates? then what do you do just take it our of the oven and let it sit and cool to room temp?

thanks

jake
Click to expand...
 
Along with what Nathan said above, I've used dry ice and alcohol (denatured)
for like 10 years and didn't notice a big difference between that and LN. The convienience of LN is the part I like the most.
Ken.
 
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