Quench plates

G

Gene Martin

Joined
Feb 5, 1999
Messages
1,068
For those of you who use quench plates and don't foil wrap your blades, how are you avoiding scale?

Gene
 
gene: Use foil with the quench plates. Leave the blades in the foil for the quench. You can then remove the blades from the foil once they are below 400F and put them back between the plates. No scale
 
Gene
when I plate them I use the foil also, I place the edge out some from the plates since it doesn't come in contact with the plates anyway..

while I'm giving it the squeeze I take a pair of scissors and cut the pack open and then blow compressed air in.. by then it's cooled enough so the air won't decarb it..
 
It sounds like that for a big blade or just doing one or maybe 2 at a time that the plates would be a good thing. When I do 9 at a time I don't think I could do that much juggling and have the blades come out any different. Just takes too much time, from what I can see.

If I did all the blades in the same thickness and used 2 super plates, I could squeeze them, but still can't cool the edge.

I'm still trying to figure out how to make this work.

Gene
 
One thing you can do is remove them from the foil when they reach 1000F. Or just go dark. They will not decarb below apx 1200, and this will give you a chance to check for edge warping. Do any straightening, and place back between the plates. This will give the edges a good shot at getting enough air to harden properly. Unfortunately, any time you use quench plates, you are insulating the edge to a degree. Which is of course exactly what you don't want to do. exposing the edge, and hitting with air will help a lot. The real purpose of using quench plates is to prevent warpage. However, with most blade geometries, the spine and recasso are in no danger of warping in the first place. The edge, and tapered tangs are left to fend for themselves. And this is where you will have the most problems. Especially with complex grinds. Using a quench plat in many cases defeats the entire purpose of using them in the first place. About the only exception is large, slow to cool flat, and or convex ground round tang and or flat tang blades. In any case use at least 2 bar of forced air. That is 28 lbs of air. Still air can work on very thin cross sections. It willnot properly harden larger or thicker blades. Mike
 
I seldom have warpage problems with anything over 1/8". I get a little, fromn time to time, with 1/8, but I can take that out by hand.

I almost always had warpage with 3/32 until I started annealing it before I did anything else with it. That pretty much solved that problem. Maybe I should just give this one a rest until it becomes a problem.

Now if this works with twist damascus, that's another matter entirely. I had one piece that twisted every time I hardened it. It sat for 6 mos, normalized and annealed, before i went to grind and harden it. It twisted, so mornalize and anneal. It warped. I finally did multiple normailize and anneal cycles. It warped again when hardened. Actually it twisted, not warped. I fianlly untwisted it rather vigorously, It will never twist again, except maybe as a mini.

Gene
 
Gene: The edge quench rate is not an issue! If you put your (same thickness) blades in a packet in a single layer, and "supersize" your plates, you can HT multiple blades, even big ones, with no problem. My furnace is
12" x 20" inside. I have done 12 big folder blades, 4 survival knives, etc.

The quench plates suck up the heat so fast that your edges will be cooled far faster than with air, even if you leave them in the foil the whole time and don't use any compressed air on them. I'm not bragging here when I say I have a reputation for high quality heat treat, and this is how I do it in my shop.
 
Mike, do you do any thermal cycling,( normalizing, stress relieving ) prior to austenitizing. Since having religously adding this to every heat treat cycle it has dramatically cut down on any warpage due to tapered tangs, thin cross sections etc.

Gene, I plate quench every air quench steel that I use, having 2 sets of plates has also allowed the first set to cool between quenchs on multiple blade heat treat cycles. It is a PITA to time everything though, I'll grant you that. I don't use a fancy set-up, just two aluminum plates on top of my large anvil and a set of vise-grip clamps. Annealing prior to grinding has solved your warpage problems ? A mini :confused: ;) I hear ya bud, it sucks when things don't work out :)

RJ is right when he mentioned how fast the plates suck the heat out. With small blades it is almost immediate.
 
Yes I do. And it is rare for me to get warpage, but I do get it from time to time. Some of the blades that I make are ground extremely thin. in the neighbor hood of .010, or less at the edge. On taper tangs, I have been known to carry them to infinity. Or down to .001 to .002 Looks great on a really thin knife. One modes is a very small mini drop point. When I say warp, I'm talking a couple of thousand ts. Most folks would ignore such things. There is no war page in the spine at all. The biggest reason that quench won't work for me, is that the only thing that touches the plates is the recasso-guard area. Which is only about 1/2, to 1 inch long at best on the various models. wish I could use them. It would make life a little simpler. Mike
 
Thanks guys. RJ, yes you do have a good rep on your blades. That's what I absolutely strive for, each and every time.

David, 3/32 ATS34 always warped on me, or nearly so. Now I anneal all 3/32 ATS34 prior to grinding. I profile the blades and anneal them. After that, seldom is there any warpage. I do that by heating to 1600F, holding 2 hours, then cooling to 1300F, holding 4 hours, then air cooling.

Works for me. Especially on fillet knives. I may grind them after heat treating. Just a little heat during grinding causes warpage. Smaller knives aren't nearly such a problem.

Gene

Gene
 
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