Issue with heat treating 154cpm and stainless foil

Will52100

Will52100

Joined
Dec 4, 2001
Messages
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Finally got around to working on a kitchen knife for myself. I used stainless foil and thought I had a good seal. When it came out of the oven and into the quench plates I found that after cooling the forward half of the blade had stainless foil welded to it in places. And the blade warped. I cleaned it up and re heat treated and it seems to have come out OK this time, instead of hold the quench plates together I clamped the suckers.

So what caused it? This is only the third stainless blade I've heat treated, and it's by far the largest. The steel was CPM 154, stainless foil wrap, not a lot of discoloration, and a paragon 18" oven. Basic recipe was full ramp speed to 1500, hold for 5 minuets, then full ramp to 2000, hold for 30 minuets then to the quench plates. Blade is soaking in liquid nitrogen rite now.

Thanks
 
now and then i get a light weld to a blade i just chalk it up to a well sealed package and a quick move from kiln to plates
 
I'm just speaking from what I've read here, no personal experience with ht for stainless.
Could you have overheated it by a wide margin during the ramp to 2k? A lot of the foils seem to have a fairly tight window and we've read about the results a lot of folks got with drastic overheating during fast ramps.
 
For good result it needs a controlled environment. Since controlled atmosphere ovens are a bit outside the price range of the average user, foil is the solution. Otherwise you get a lot of decarb due to the high heat and soak times. There may be other factors, but that's the key part I remember.
 
I've had similar problems with foil sticking to the blade. Suggest you make sure your foil is rated to the highest HT temperature . Also, I spray a light coat of WD 40 on the blade, which helps with discoloration and may help on the welding problem. Finally, I found I was clamping my plates too firmly which may have contributed to the welding. Moderate clamping ok, go bit easy, especially immediately after pulling from the oven. (note on WD40. The first time I used the stuff I gave it a heavy dose of WD40, then sealed it all in foil. I had a belch of flame and the packets ballooned up.
 
Phil705 said:
I've had similar problems with foil sticking to the blade. Suggest you make sure your foil is rated to the highest HT temperature . Also, I spray a light coat of WD 40 on the blade, which helps with discoloration and may help on the welding problem. Finally, I found I was clamping my plates too firmly which may have contributed to the welding. Moderate clamping ok, go bit easy, especially immediately after pulling from the oven. (note on WD40. The first time I used the stuff I gave it a heavy dose of WD40, then sealed it all in foil. I had a belch of flame and the packets ballooned up.[/QUOTE]

well, atleast you know you got the oxygen out ;)
Click to expand...
 
we've been cutting the packets and putting the bare blades btw the plates.
We planned to just put the foil packets between the plates from now on, but haven't tried it yet. Should we expect problems?
 
This is the first time I've had it happen, I've done a couple test blades, one folder blade and now the second time I heat treated the kitchen knife it didn't do it. Next time I'll give a light coat of WD. I had been cleaning the blades really well, that may have helped the welding. The foil is rated for the temp though, may just have been a bad section?
 
A light dusting of cheap baby powder will stop the welding and you don't have to worry about the WD-40 flaming up or ballooning the package. Baby powder is Talc which is a rock in a powder form so it wont burn even at these temps.
 
Cool, thanks for the tip. After a dip in liquid nitrogen the blade came out even more warped than it was the first go round. I am begining to think I'm going to have to do a normalize cycle and anneal it and start over. The small blade I did warped just a bit, but since it hasn't been ground yet and is getting a tapered tang I think I have enough material to play with.
 
darrin sanders said:
A light dusting of cheap baby powder will stop the welding and you don't have to worry about the WD-40 flaming up or ballooning the package. Baby powder is Talc which is a rock in a powder form so it wont burn even at these temps.
Click to expand...
:thumbup::thumbup:Yep we do the same thing on die sections. Usually square blocks with sharp corners. The foil tends to weld to the corners. Baby powder prevents the bond, also makes the heat treat room smell better.
 
I use monkey Butt powder... shhhh, dont tell anyone:)

it was the only baby powder I could find in the house lol
 
The baby powder idea is great. Thanks!

I tried WD40 in the past as well, but I just end up getting a balloon instead of a foil packet, so I typically heat treat without any combustible. I've done a whole bunch of CPM154 blades using the higher temp foil, and I still get light welds on occasion. Typically, they are on an edge or corner where there is the highest contact pressure from the plates. Usually I can still peel the foil off using plyers, and any other issues are taken care of with finish grinding. Lighter plate clamping helps.

As to the warping, I've only had one blade warp on me when doing a foil heat treat/quench. It turns out that I didn't cut the foil large enough to start, and the double-folded seam at the end of the packet actually overlapped the tip just a bit. When I clamped the plates, the pressure from the extra foil on one side of the tip bent the soft tip away. I now make sure my packets are a single layer over the entire blade area with the crimped seams outside the profile of the knife.

Daizee, I don't even want to think about me trying to cut open a nearly 2000F packet of knife/foil in order to get a blade out to plate quench. I just plate the entire packet, and I cut it open once it's cool or at the earliest, when all the color is gone from the packet. Cutting open the packet while it's still at temp is going to cause some mild decarb, and you'll have a slower quench that way.

--nathan
 
I pre-heat to 2000F and then put blades in. I would think the ramp up at full would create an over temp problem. Even a 200 degree overshoot is going to exceed the max temp for the foil. The soak at 1500 isn't doing much, that step is really designed for thicker sections than we deal with. A 30-40 minute soak in a pre heated 2000F is going to be the hardening cycle. So far, I have had no warping even in several 10" fillet blades in CPM154. Since i started putting a light coat of WD40 on the blades, I have had very little welding. I did have problems when I tried having the blades in the oven while ramping up. I also only lightly clamp the packets in my aluminum plates. Still straight, but less welding. Hardness out of the oven runs about 62-63.
Chip Kunkle
 
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