Odd finish after quench.

Belstain

Belstain

Joined
Sep 17, 1999
Messages
320
I heat treated a knife thother day and after quench it had little spots all over it. Like water drops but part of the steel. I finished it to 220 before heat treat. What causes this?

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I'm a Schizophrenic and so am I
 
Did you heat treat in a kiln, forge, or use a torch? If you did it in a forge or with a torch, sounds like you got it too hot (cooked the blade) which to my understanding means, that the elements in the steel started seperating. This usually happens down at the point area, due to it being the thinest part of the whole blade. I guess an easier way to say it would be, you possibly went to far past critical. I've have it happen to me twice and only recently. One was on a very low layer count piece of Damascus and it happened only at the tip, the other time was on a piece of 1080 and the same thing happened. After three draw downs and the finish sanding, the spots wouldn't go away, so I very carefully reground the tip back till the spots were gone (dipping in water the whole time to keep from ruining the temper. Changed the looks of both knives, but they ended up fine. Hope this helps, and I am correct. If not, then I hope someone helps us all and elaborates some more.
 
By golly Bearheart I think you hit my problem at least. I heat treat in a homemade forge and try to do it at night. When I just start to see a glow I'll start testing with a magnate. I did that one during the daytime though. Thanks
 
I was reading an article in one of my blacksmith books and that effect was referred to as 'bubble steel' and was a thing to be desired, not necessarily a bad thing. I can't remember all the particulars but it's happened to me on several occasions and I can't see where it damaged the steel. 1095 seems to be affected most often. I guess it might have something to do with the carbon content in it. Of course, my memory is about as good as my hearing. And I'm blind in one eye and can't see out of the other.

As far as the finish, with the kind of knives I tend to make, it doesn't affect it at all. I just polish up the blade and ignore those spots, unless it's a fancy piece. Call me Mr. Rustic.
biggrin.gif
 
I was under the impression that those were martensitic rutilations, and usually indicated a proper hardening. When heat treating with a forge or torch with no heat treating foil, it is advisable to leave a few millimeters of steel extra on the blade to be ground off after heat treat. This is both to allow a satin or mirror finish, and to prevent warpage. After all, we have to grind off surface decarb anyway after a heat treat. What did you quench in?

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Oz

"Sticking feathers up your butt does not make you a chicken!"
http://www.freespeech.org/oz/
 
Bought a 1095 blade that was heat treated by Paul Bos once. It had smwll circular ,very shallow marks on it. Was told this was from the heat treat. Sanded out fine and made a good knife.I haven't ran into this on my own but then I edge quench. Got a good temper line on thew last one will shoe it when I'm done.
Take Care
TJ Smith
 
I had this happen on a 1095 blade a couple of weeks ago. I wondered if the quenchant (trans. fluid and 30 wt.) was too warm from doing a couple of other blades in it previous to this one. Could the boiling quenchant do this, or am I way off on this? The blade hardened okay though.

Dan
 
This happened to me too, but I thought it was maybe because I pulled it out of the quench too soon....Glad to read about other people's experiences with this. (I was using steel cut from an old 2-man saw.)
 
I am using 1095 in my gas forge. After sanding the spots out the blade seems fine. Slapped a quick handle on it and went out in the woods to test. held up great! I think the spots are caused by overheating though.
 
1095 in damascus will give you spots if not heat treated properly. Water (brine ) is best.
This steel requires a fast quench . So as the blade gets thicker the hardness changes.

I quit using it 8 years ago for this reason.


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Web Site At www.darrelralph.com
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