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Heat Treating and Metallurgy Discussion of heat treatment and metallurgy in knife making.

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  #1  
Old 11-18-2008, 09:51 PM
AlanR AlanR is offline
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Join Date: Jul 2006
Posts: 115
ATS34 HT question

Hey again, all!

Trying ATS34 for the first time since 1095 gave me troubles. I've plate quenched 440C easily a few times in the past and thought I had the process down - I think I was wrong. I'd like your opinion on my suspicion (am I close to correct? - I'm trying to gain an understanding of heat treating) and also a recommended fix (if any is thought to be needed).

Problem:
After the plate quench where the blade was almost able to be held in hand I cut the foil off and slid into my gloves and noticed some weird coloring. At the tip, approx the last 3/4" is some dark grey shading. I think the plates were on the ricasso and not touching the bevel much at all. There are blues/oranges present that I typically see in my 440C on the rest of the bevel. A file skates across the blade except at the darker area where it seems to just start to want to bite in. Blade edge approx. 4.5".

Question: Did the tip maintain heat longer if it wasn't touching the quench plates? It's the furthest part from the ricasso so this might seem to make sense to me.

Since the tip is the thinnest and most liable to breakage (?) would it be ok for the tip to be slightly softer than the rest of the blade?

To fix this time: Anneal and re-heat treat?

To prevent next time (if the problem is what I suspect above): Put the edge of the blade at the edge of the upper plate so that it can ride on the bevels? I guess the ricasso would need to hang out from the lower plate so no bending is induced.

I look forward to responses, thanks!
-AlanR
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  #2  
Old 11-18-2008, 10:27 PM
AcridSaint AcridSaint is offline
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Location: North Carolina
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ATS-34 will harden in air so you shouldn't have a problem if the tip cooled slower. In addition, the thinner cross section isn't able to hold heat as long and the thermal conductivity of the plates will remove heat from sections that they aren't touching. Pretty much, the tip will harden no matter what.

Sometimes you'll get odd colors on stainless, I believe it usually means the foil wasn't sealed well. I doubt you'll hurt anything heat treating again, I wouldn't bother annealing, but I would double wrap.

Was the tip very close to an element? Maybe there is a possibility it was over heated.

For what it's worth I usually plate quench blades before they are ground so they come out completely flat. All of my blades that have been ground first get air quenched so I can watch and adjust any warp.


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Last edited by AcridSaint; 11-18-2008 at 10:29 PM. Reason: I wanted my post to make some sort of sense
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  #3  
Old 11-19-2008, 01:55 AM
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mete mete is offline
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The colors are nothing more than oxidation, a bit of air was in the foil .It should polish off easily. I can't comment about the 'soft' area without knowing your whole HT details.
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Old 11-19-2008, 07:11 AM
AlanR AlanR is offline
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The blade was edge up in the middle of the chamber which is approximately 14"x10"x18" if I had to guess. I'm just going to mark this one up as a mess-up on my part because, from what I've read, as long as you can control temperature and time ATS34 is pretty easy. I just wish I knew what I did.


I'll pay more attention on the second try and hope for the best because this is the best looking blade I've done so far.

Thanks for responses.
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