Heat Treat Question - O1

General Specific

General Specific

Joined
Nov 17, 2006
Messages
213
Hi All, I've been lurking for some time here trying to soak up at least a tiny fraction of the tremendous knowledge that you guys have accumulated and shared so unselfishly. I have a question or 2 about heat treating that I'd like to ask. At the moment O1 is what I'm working with.

I'd like to know if tempering can be delayed after the quench (by holding the blade to 130 deg. F) or whether there is a definite window in which it must be done. In other words, if the blade is held around 130 deg. F after the quench, at that point are there any metallurgical processes that are progressively causing a more stressed state and increasing the possibility of stress risers or weakened end product? If so, is there a higher temperature below the intended tempering temperature that would preserve the knife's state without "counting toward" the tempering process.

I ask this because I have a co-worker who wants to do something with his kids, and they're real excited about making their own knives as a family project. I would like to heat treat the knives in series and hold them after they are quenched in the toaster oven at a lower-than-tempering temperature until the last knife is quenched and then ramp up the oven to the desired tempering temp. I don't know how many kids he has, but it sounds like a bunch...

He's going to Harbor Freight this weekend and is looking for a very cheap grinder. Any suggestions as to what they might have that would fit the bill and have plenty of aftermarket belts, etc... would be a great bonus. Thanks again for helping with my new addiction.

Regards,

Dave Knill
 
Hi Dave, since it's a project for the kids I'd suggest he put them to work with files instead of trying to make a belt sander from HF work. The O-1 will be able to wait long enough for all of the blades to be quenched, although tempering the first one longer than the rest won't hurt anything, as long as you don't go over the tempering target.
 
Thank you for your reply AcridSaint. His previous grinder burned up last year, so I think he's looking to replace it with something that might be used to help with knifemaking in the future, but I'm not sure. I believe he fullly intends for the kids to use files exclusively to put the bevels in. He's a very responsible guy - a firearms instructor where I work. I don't think filing will be too bad for any of the somewhat larger kids, since I'm going to give him 1/8" stock for this first go around. Regardless, I appreciate your input and have noticed your contributions in other discussions of heat treating. Have a great weekend! (it's almost here, anyway).
 
If he's going to have them file the bevels then I'd have him look at a disc grinder for cleanup. HF has a few different belt sanders that come with discs and also a couple flat out disc grinders. The 9" ones can use regular sandpaper cut to shape and the larger ones can get spendy on the discs, so watch out for that. You can buy a 9" disc from them as spare parts for one of their belt sanders and mount it yourself as well.

Didn't know anyone noticed my posts around here, better learn to keep a lower profile! Anyways, I'm no expert so hopefully someone will come by and give you more detailed advice on the heat treating, I just tell folks what little I know about.

Good luck!
 
I've just recently started using O-1 steel. #13 now. Because of an injury there is a substantial delay in my ability to get my heat treated knives from the quench to the tempering stage. It takes me nearly an hour to hobble from my forge area to the oven, and I have to carry the hot knives in a bucket held in my teeth, on crutches, up hill both ways.:) Because of the close proximity of hot steel to my face, and already having busted my butt when my crutch went in a gopher hole trying to hurry, well I quit trying to hurry. I heat treat the blades in batches of 3 to 5 at a time. I need to cool the oil by adding more between each blade, so by the time the last is done the first is quite cool. I clean them up a Little and lightly sand them. Them I make the long trip up to the oven. One hour at 400 and then over night in the freezer and repeat 2 more times. long story short the results have been excellent. I can find no functional difference in tempering when they are still warm and tempering when they have cooled to room temp.
 
Thanks for the information guys, and for the link to the other thread. Kevin Cashen has mad metallurigical skeelz. Unfortunately, although I have read some of his detailed HT discourses I did not process it all properly. I usually run across a dumbed down explanation of things written by others and then go, "oh, that's what the devil Kevin C. was explaining". Yesterday I had to re-HT a blade because I did not realize that formation of the martensite (at least a large proportion) occurs between ~450F and ~130F. I know I'd seen references to this in past threads, but terminological r-tardness on my part blinded me to the points being made. Anyway, thanks again for the input. Weekend imminent!:thumbup:

Dave Knill
 
General Specific said:
Thanks for the information guys, and for the link to the other thread. Kevin Cashen has mad metallurigical skeelz. Unfortunately, although I have read some of his detailed HT discourses I did not process it all properly. I usually run across a dumbed down explanation of things written by others and then go, "oh, that's what the devil Kevin C. was explaining"...
Click to expand...

:D And believe it or not, I am dumbing it down quite a bit before then;)
 
It's just the difference between somebody who's studied his metallurgy and us barely-iron-age hammerbangers :D

Luckily for us, we can ask da shaman. :D
 
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