Decarb problem

N

Nylunds knives

Joined
Jan 6, 2008
Messages
109
Hello!

I have some troubles with decarb.

I'm using a new big, 110litre oven for ht. The oven is quite expensive to warm up and isn't as easy to open as a smaller ht oven. This means that I'll have to do batches.

When you are using ssfoil for protection you can only ht and quench one blade at a time.

Are there any other ways to protect the blades from decarb that I could use with my oven? Any type of powder?

How big is the decarb layer, maybe I could just grind it away?



Regards Jakob
 
We need to know the type of steel you are using, the foil is for stainless where you are doing and air quench. There is a coating that some use for preventing decarb for high carbon steels. You can put multiple blades in the foil pack and given you situation that may be the best way to go, you can use A2 or any number of stainless steels with and air quench.
 
The steels I've had problems with is aeb-l, rwl-34 and in the future I will start using 154cm and cpm 3v.

I've not had any problems with 01 and 1080. I've used a type of hot paint on these steels instead of foil and it have worked good.


I've taught about multiple blades in a foil pack but it's not that easy to handle such a pack.


Is there any powder coatings for stainless steels?




Regards Jakob
 
Why ony one envelope? We routinely do 1/2 dozen at a time in a much smaller kiln.

There are powder compounds as well as liquids that also work fine, but not as good as foil and plate quench.

Rob!
 
LRB said:
PBC powder is available for temps above 1650°. It is called PBC Special. Go to
http://www.rosemill.com/default.asp?pageid=27391
Click to expand...

That is intressting!

USA knifemaker supply have it aswell but I found this information about it on their site: "PBC Special is for parts treated from 1650-2250 F (not to be used with ATS 34, S-7, or other steels high in chromium, nickel, or vanadium)"

This mean that I can't use it on 154cm, right?



Regards Jakob
 
Last edited:
Rob! said:
Why ony one envelope? We routinely do 1/2 dozen at a time in a much smaller kiln.

There are powder compounds as well as liquids that also work fine, but not as good as foil and plate quench.

Rob!
Click to expand...

How do you do exactly when you're doing more in one envelope? One big envelope and some very big aluminium plates or? How big plates do you need for ½dozen blades?

I saw that you have a anti scale product on your site, can I use that on stainless steel like 154cm and how good is it?


Regards Jakob
 
Nylunds knives said:
How do you do exactly when you're doing more in one envelope? One big envelope and some very big aluminium plates or? How big plates do you need for ½dozen blades?

I saw that you have a anti scale product on your site, can I use that on stainless steel like 154cm and how good is it?


Regards Jakob
Click to expand...

My main set of quenching plates is 12" x 24" and will hold 8 envelopes side by side without too much trouble - though we only do 6 max. I also have a smaller set 8 x 18 that I use if there are different thicknesses in a batch.

The compound on our site is ATP-641 and you can also get it from Brownells. It is rated from 1000 to 2300F degrees. We ordered it because we were using TURCO for oil quench steels and K&G didn't have any.

I am told it is used by knife makers all over the world and some have referred to it on this site with mixed reviews. I am waiting for documentation and literature from the company, so I can't personally vouch for it yet.

I have used it only on two blades so far - and likely not as it was intended. CPM 3V tempers at 1025F degrees so an unprotected blade in temper winds up with some ugly oxides that make clean up a bit harder. In this case, after cryo, I dipped them in ATS-641 and then did tempering. The results were better than unprotected, but less than I'd hoped for. The coating is supposed to mostly flake off upon cooling, and although I didn't touch them while cooling, I think there was compromised protection to some degree during the second temper. After the second temper, what little didn't flake away, just washed off easily with warm water. I have seen no cautions in company literature yet about high chromium steels. (Wonder what that's all about?). I'll update our website as we get more experience and more literature. Our intent is primarily for oil quench steels since I'd be a hard sell for anything other than foil for "air quench" steels.

Rob!
 
Rwl-34, aeb-l and 154CM can be oil quenched aswell as plate quenched.

Do you think that atp-641 is good enough to protect 154cm when oil quenching?

Also how thick are the alu plates, 1 inch or more?



Regards Jakob
 
Nylunds knives said:
Rwl-34, aeb-l and 154CM can be oil quenched aswell as plate quenched.

Do you think that atp-641 is good enough to protect 154cm when oil quenching?

Also how thick are the alu plates, 1 inch or more?

Regards Jakob
Click to expand...

I can't comment on oil quenching 154 because I just can't imagine why anyone would want to. It's not something I'll be trying. My plates are all 1" thick.

Rob!
 
Got some details on the ATP-641

Spec Sheet

I understand it is normally thinned by knifemakers (with water). Unthinned and dipped, the coating was probably .070 (70 'mils') - way too thick. The rep suggested a few tablespoons of water per pint would thin it enough.

I'll keep posting as I get experience with it, but none ready for HT right now.

Rob!
 
So, is Turco hard or impossible to get now?
And it appears that ATP-641 can be used with ATS-34 and CPM154, correct?
Dan
 
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