question about hardening this steel!

E

elyfarms

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Jan 28, 2007
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I have a how to question for anyone that might be trying the new cru forge v steel that was written about in the December 2009 Blade Magazine. I purchased some of this steel and have been trying to make some blades from it. My problem seems to lie in the hardening process. I first followed the spec sheet on the steel and pre heated to 1225 degrees and equalized the steel for ten minutes, then raised the temp to 1525 degrees for 10 minutes and edge quenched the knives in 100 degree oil. Doing the file test left me unsure if the steel was hard as a triangular file would grab just slightly. It didn't have the same hardness feel that 5160 would have after hardening and yet upon trying to drill some holes in the tang ( ya I should have done that before hardening ) the drill bit would not penetrate the rear center of the full tang. Is this the way a powdered steel acts compared to a steel like 516o? I would appreciate any help. I have even raised the temp to 1550 and quenched the steel and the edge of the blade doesn't seem any harder that the previous method. I have double tempered at 400 degrees with one blade and tested the edge and the knife seemed to cut very well. Want to get the best blade possible here with this steel. I think it will be good stuff if I can figure it out!
Anyone can e mail me their suggestions.
 
The temps you quoted sound like you're using a calibrated oven
Are you..?
At the needed temps, you'll need to protect the steel from Oxygen
or you'll have decarb. Use SS foil or a coating like PBC.
Forget the edge quench on CruforgeV. A fully heated blade, edge quenched,
will give you underhardened steel...and fire.
 
like Russ said, forget edge quenching. Your file is likely cutting your decarb layer. File tests are borderline worthless. Carefully grind your blade after tempering (never heating it over your tempering temperature) then put an edge on it and cut something hard (like the spine of a Buck Knife :D ) then you'll know if it hardened or not. A file test tells you no more than if your surface is soft enough to pick off with a file, it says nothing about the structure of the metal you will still have in your finished blade

-Page
 
If I fully harden these blades can I use a torch to soften the spine so that the knife is differentially hardened or is this a waste of time? And if I use foil or the PBC do you pull the blade from the kiln and submerge the blade wrapped in foil or PBC dirrectly into the quench oil? How long is necessary to leave in the quench and should the oil be heated to 100 degrees or so? Thanks for any help.
 
You can use a torch to draw back the temper on the handle and spine. In fact, this is my preferred way of doing it as opposed to an edge quench. You'll have a more uniform structure throughout will a full quench, and then the over-temper you do on the spine and tang will add more toughness to those areas.

As for foil/PCB... I'd say try the PCB if you want scale protection. Or even a thin satanite wash. Foil needs to be removed before the quench, and you risk loosing too much heat, not to mention trying to fiddle with glowing steel. PCB is an anti-scale coating that works great if applied correctly, and you just quench as normal.

I've heat treated Cru Forge V without scale protection in a controlled oven. It will have some surface decarb, but I finish grind after heat treating anyway, and the surface decarb is ground away. You might be getting a bite with the file because of a thin decarb layer. Run the file down the edge a few times to remove any decarb and then repeat the file test and see if you get better results. As has been said, the file test is just a quick test to see if you're on the right track.

The Cru Forge V I've finished out seems to take a very keen edge and hold it pretty well.

--nathan
 
Thanks for the reply Nathan and all. How hot have you been heating cru forge v before quenching and how good is pretty good for edge performance?
 
I've been doing very similar to you: 1520-1525F with a 15 minute soak. Quench in warm medium speed oil (AAA for me). What oil are you using, BTW?

I guess my performance rating was somewhat subjective :D. Basically, after tempering, I put an edge on and proceded to cut stuff. I chopped into 2x4's, cut nylon rope, cut paper, cut carboard. I had no edge deformation with chopping, and the edge was able to maintain its keeness even after all the cutting. Yes, it's not going to be hair whittling sharp after all the abuse, but it still shaved and "felt" sharp. Some other blades will still shave but don't feel as sharp. Basically, it felt more keen than some other blades I've tested from O1 and 1084. But that's just me, and edge geometry is going to vary slightly from blade to blade which can affect that subjective test.

--nathan
 
The oil I use is Conoco Quench 22 and I have also tried Mobile medium quench oil. My test results have been the same even with the problems I have been talking about. I did finish one blade with the edge quench and felt it cut pretty darn good. It may cut better yet as I sharpen it more times and get rid of the decarb area. This will be a knife I keep and carry for my own experience. I think I will try a full hard and spine draw. Is the spine draw hard? I have read about it but never done it.
Mike
 
Not hard. Just submerge the edge and tip in water and use a small torch to heat the handle. I place the entire edge/tip in water and submerge about 1/2" of the blade in the water. Start at the butt, and walk the heat and colors forward until you reach the ricasso area. Then, focus your heating more on the spine portion of the blade, and move the heat colors down toward the edge about 1/2 way and towards the tip.

Water boils at around 212, so if you see the submerged blade start to boil the water, just back the heat up. The colors you're looking for are going to be in the blue ranges, but they'll vary as they're just oxidation colors. I shoot for blues/dark grays which will get you above 525 typically to around 700. You don't want the blade to glow, just heat it up past your temper. Careful not to overheat the thinner portions of the edge past your temper.

--nathan
 
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