How to fix Warpage

B

BIGRTEX

Joined
Dec 19, 2006
Messages
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Welcome to Bladeforums!

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I dont know what to tell you.
Perhaps one of them guys that do a lot of HT with your steel will be able to answer your question.

In my own case as I only quench the cutting edge, I guess if a blade ever was bent I would just bend it back to straight.
 
If your grinds weren't equal you can get warping. What I mean is if you took off more steel on one side than the other it can warp.
 
So what would you tell him as to how to fix it now?

I forge my 52100 blades from ball bearings, so it's normal that they are always bending off to one side or the other as they are forged and HT.
so it's no big deal to wack them a few more times to make them straight .
 
Bigrtrex, shine the blade up and then put the tip in a padded vice (wooden jaws or some leather around the tip). Wet a cloth until it is dripping and then heat the spine of the blade with a torch where you want to move it while cooling the edge with the wet cloth. When the spine gets bluish in color the blade will be very prone to moving and taking a set where you move it. Since you will have the torch in one hand and the cloth in the other it is often necessary to lean your hip into the tang of the blade. A slight correction is all that is needed at this temp so be careful or you may over do it. Also be certain to keep that edge cool.
 
When I quench the blade, I take it out of the tank after it stops rumbling. It is still 700-800F at this point. I give it a good look down the blade. If it has any warp, I stick it in the vise and give it whatever twist/bend /tweak it needs (or I put it on the anvil and hammer it) . Don't be shy here. If yo do it before it drops below 300F it will bend any way you want . Once the Martensite sets it is brittle, before then it is rubber.
Stacy
 
Kevin, I'm assuming that the heat is applied straight down on the spine, and the wet cloth is on the edge?
Is the torch Ox/Acet, or will Mapp do?
Thanks
 
Stacy is right, the best way to keep that from hapening is to do it during heat treat before the steel cools and "sets up". I hire my heat treat done by the same people that does the shop I work for because they do it for free! but same goes anywhere, if you hire it out specify that you want it kept straight and you be shoked at how straigh you get back. If you do it yourself just dont let it get to cool. For now....break out the torch....but be careful
 
Questions:

Did you actually set that furnace to run overnight and ramp so it's ready when you come in? The old "stir for 16 hours" thang? :) Neat. LOL

How hot is that blade when you spritzed with the water? You may have caused your warpage there. Best to keep the quenchant (gas) evenly distributed.

Argon will be a lot better than N2 for displacing air, especially if it's "free".

After you get it straightened, a 16hr hold in a dry ice/solvent bath or a 4 hour hold in LN will aid conversion of austenite to martensite. 440C has a sub-ambient temp for full martensite conversion. Temper afterwards.

Are those HPLC columns? What kind of phase? :)
 
about a year or more ago I forged a 5160 blade from a John Deere rock shaft.
Now I cant say I really looked at the blade very close after I quenched it, but I can say that as I carried it into the house to temper it in the oven Im sure I glanced at the blade and I never saw any sign that it had warped yet.
But after I took it out of the oven after the temprting I had a nice fat bend in the blade.

I blamed the tempering oven.

The same thing happend a few months later.
Again I think I checked the blade close enough out of the quench as I carried it into the house to temper it and I didnt see and warping.
I am sure that had the blade had a bend on it as I walked with it that I sure should have been able to see it.
But again, once I took it out after it was tempered in had a big fat bend in it.

Again I blamed the kitchen oven.

From that day on I have always placed my blade spine in a drill press vice to hold them straight during the temper in the oven and I have never had another problem.

Does the drillpress vice trick really help?
I dont know....

The oven I use is kinda old and it does not heat foods the most even. My guess is that perhaps the way I used to lay the blades on their side on the oven racks also might have helped warp the blades.

The drillpress vice keeps the blades standing up straight and so perhaps now they heat more even too.....

All I know for sure is things seem to be working better for me now...
 
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