Warpage - Is it my furnace or my grinding?

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reedje777

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Sep 27, 2011
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So I just ruined my second blade (1095) from trying to correct blade warp out of the HT. I snapped both in two. I've done quite a bit of research on correcting blade warp once you get it and I know what I did wrong on both occasions when trying to correct the problem (working it too cold).

What I'd rather do, however, is avoid blade warp altogether! I have two theories:

One, uneven blade grinding. I've only done two knives now so I'm still learning. This could definitely be the problem.
Or
Two, I'm using a homemade furnace that only heats the first 6-7 inches of the blade evenly. The OAL is around 8-9 inches. The handle doesn't get as hot so I'm wondering if this effects the blade and causes warp in the quench (brine). Is this a possibility?

Any thoughts?

I bought two aluminum plates to interrupt the quench at 450 degrees and then cool the rest of the way in the vise between the plates but I haven't tried it yet. Also, when I was practicing this cold, this technique would still allow my blade to warp some as only the handle gets firmly flattened. There is still a bit of play with the blade as it's been ground.

Help me please!
 
Try quenching in oil, any correcting you do needs to be done while the blade is still hot. If your correction did not work out re-heat the blade, straighten and then heat treat again. The plates won't help you unless you are using air hardening steel.
 
Quenching thin stock in brine is a challenge. Uneven grinds is not likely the problem. You can hand straighten a blade out of the quench; using hot gloves count a slow 5 after the blade goes into the quench, look along the spine of the blade and straighten by eye.

Fred
 
I think I need to try oil. I can't afford Parks or K Quench so I guess it'll be Canola. I should be able to interrupt the quench that way at 450. I tried to do that on my last knife with brine but it was 150 degrees within 3 secs! I couldn't catch it fast enough! I don't think brine will let me repeat the interrupt consistently even if I did catch it right...

I can still use the plates after I oil quench. They would help cool it after I interrupt at 450, straighten by hand and then clamp to cool to 120. That's my theory. Sound right?
 
Uneven Grind is normally the main culprit. Also not going into the quench perfectly straight. Uneven heating is possible but quenching in brine is more than likely the problem. Get some Canola or Peanut oil. I prefer peanut myself, smell a bit better and has a higher flash point. If you can't afford parks then get one of those. Heat to 130-160f and have at it.
 
Like Chuck said, not going into the quench straight can warp a blade REALLY bad. I once dropped a blade into the quench tank and it went in sideways. It warped into an ugly corkscrew.

Personally, I think sometimes steel just likes to move. I've hardened pieces of surface ground O1, going from a digitally controlled salt bath to AAA quench oil, and they have warped at times.
 
Ok, it seems a given that warp happens even to hardened veterans. What do you guys think is the best method for fixing warp? An interrupted quench at 450 degrees and straighten by hand?

What If I clamped the blade between aluminum plates and tempered the blade for a couple of cycles? Would that get the warp out?
 
You can give that a try. Probably won't work but might. Usually need to put it in a 3 pin jig right out of a 400f oven. Move it a little and repeat. Best thing to do is quench it thick and grind it thin. The if you warp it you might be able to grind it out. The absolute best is find the right process that does not warp. Then you don't have to worry about it. You will still get the occasional warp and even a cracked blade. Just the way it is. You can allways go to air hardening steels and use the quench plates. Not for me though. I have a blade I have straightened and re-heat treated 3 times now. It is still warping. I do thermocycles between each try and still no go. Yet I did a longer and thinner blade at the same time same material that came out great. Like Nick said sometimes the steel just has a mind of its own.
 
I stress relieve all of my blades now after grinding and the warpage has gone done to almost nothing.
 
Yea, I too stress relieve after grinding. Then I do another normalize before the quench. I can usually tell why a blade warped by looking at it, but then there are times it can be baffling.
 
One thing that that can cause warping is leaving the blade in the quench with any weight on it. I have had that happen from leaving a blade in the tank leaning up against the side and I was reading a post by one maker who said that he was getting warpage because the rack in his tang was uneven.
 
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