Stubborn warp

shamu

shamu

Joined
Jan 18, 2010
Messages
217
forging a knife in 1075, and there is a warp that returns after i fix and then normalize the blade each time. it's like the thing has memory. i can post pics if necessary.
 
Be warned sometimes the memory can take a while to return.
I had straightened a chef's knife a while back and everything seemed fine. Got the handle on and finished, and the damn thing had warped again....
 
shamu said:
ill give that a try. thanks
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That is stubborn. I would do it in the 2nd temper, over bending it on a straight bar. I've had one particular blade that took 3 extra tempers, going further in the over bend, but even that one eventually came straight.
 
How bad is the bow? If it's not to crazy then clamp it straight for the very first temper. Thats how I do all my blades. If you do get it straight with the first temper then on the 2nd temper you will most likely have to bow it past straight then temper. But simple carbon steels usaly comes out nice and straight if clamped straight for the first temper.
 
Here's my attempt to show how warped it is.

mLE13LL.png
 
To me look like right side is almost straight and left side look like bend ? Is it possible that it is how you forge both side ? But I look in picture , maybe I'm wrong . . . . .
 
Natlek said:
To me look like right side is almost straight and left side look like bend ? Is it possible that it is how you forge both side ? But I look in picture , maybe I'm wrong . . . . .
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it should have a distal taper. its definitely a warp. i had an experienced guy fix it twice, and it would look great just after the fix...then it would just warp again.
 
I would harden it, and after a 4-5 count in the quench pull it out and stick it in a vise between plates to let it cool off and see what you get. If it's still warped, fix it like JT suggests in the temper.
 
You need to be prepared for warping during grindingly well. As long as you did everything correct during heat treat it should be stable but there is always a chance.
 
Sure looks like it is just more tapered one one side vs the other rather than being warped. You can keep hammering on the other side, but might hammer out thinner than you want. You need some grinder time with it anyways probably, so get to good 'nuff then hit the grinder. You can even out the taper there. You'll need to normalize before the heat treat after for sure because I've found grinding one side much more than the other really makes it want to go wriggly at the quench if not normalized and thermal cycled.
 
initially i thought it was something i should fix on the grinder -- i felt like it had "more meat" on one side. but this thing was straight as an arrow, and then as it cooled developed a warp prior to HT. I'll try JTknives JTknives and kuraki kuraki advice.
 
Hmm I've never seen the steel warp during an air cool, only during quench. Are you laying it down on the anvil to cool. If so maybe the anvil is sucking heat out of that side giving you almost a one sided plate quench and causing the warp. If that's happening hold it in your tongs and gently move through the air to get well cooled before setting down. If you're using a propane forge you could also try the lazy man's annealing. Get it to straight and critical, stick it in the forge, then shut the forge off and let it all cool together. Should make it cool slowly thereby annealing it some and you really shouldn't get any warping at that point. I don't have the setup for proper annealing, so I do this with each blade just for whatever little extra it does to soften things up for grinding and drilling.
 
lanternnate said:
Hmm I've never seen the steel warp during an air cool, only during quench. Are you laying it down on the anvil to cool. If so maybe the anvil is sucking heat out of that side giving you almost a one sided plate quench and causing the warp. If that's happening hold it in your tongs and gently move through the air to get well cooled before setting down. If you're using a propane forge you could also try the lazy man's annealing. Get it to straight and critical, stick it in the forge, then shut the forge off and let it all cool together. Should make it cool slowly thereby annealing it some and you really shouldn't get any warping at that point. I don't have the setup for proper annealing, so I do this with each blade just for whatever little extra it does to soften things up for grinding and drilling.
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i'm using a coke forge, and laid it down on the side of the forge. i think i may have laid it on the anvil also though.
 
Warps could be the result of uneven heating and uneven cooling. It applies all through the process, not only to the quench
The rate of heating and cooling should be as even as possible all over the blade with respect of its simmetry.
 
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