Forging O1?

J

JoshEarl

Joined
Sep 30, 2007
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In the other thread that's asking for comparisons between O1 and 1095, someone mentioned that O1 will air harden very easily.

So I'm wondering whether the bladesmiths out there avoid O1 because of difficulty in drilling holes after forging.

I had a blade that I forged and ground recently that I got pretty much finished, but I needed to drill one hole in it and couldn't do it. I tried normalizing and annealing, and nothing helped. I even tried a cobalt bit.

Should I stick with carbon steels? I do all of my heating in a gas forge, so spheroid treatments aren't an option.

Josh
 
In my experience 01 will air harden after being heated to anything even near a dark red heat. I use cobalt bits exclusively for tang drilling, and the 01 ruins them if it has been heated. You can heat it red hot, and drill before it cools even with a standard bit, but doing that seems a drag to me, and I know I would burn myself before it was all over.
I have read where 01 needs to be hotter than simple steels when forging, so you may want to research that also. Randall Knives have had good luck forging it, so it is not necessarily a real problem, just more intensive to work with.
 
I did try the red-hot drilling thing on this blade, and it actually melted a 3/16" drill bit. The tip mushroomed back. I got about 1/8 of the way through the 1/4" thick tang. :mad:

I noticed the difference in difficulty while forging. The O1 needed to be yellow-orange before it started to move much, and it also didn't until a higher heat range than my 1084.

Probably going to stick with 10xx steels for forge work...

Josh
 
Do you have a torch? I harden my o1 knives all the way through, from tip to tang, and when I make a hidden tang knife, I drill the pin hole after putting the handle on. I use a torch to anneal the tang after heat treating. You have to be careful not to heat the tang past the critical temp, or you'll be back where you started. Heat it up to a very dull red, and let it cool slowly. So far this has worked for me, no problems. Also, I do use cobalt bits.
 
Phillip, do you think multiple heatings to dull red would soften the 01 tang even more?
 
LRB said:
Phillip, do you think multiple heatings to dull red would soften the 01 tang even more?
Click to expand...

Probably. The more times you heat it and cool it, the more it's like a sphereoidize anneal. Just don't get it hot enough that it'll harden, and don't soften the cutting edge. ;)

Usually the tang is 35-45 RC when I'm done with it. More of a spring temper than fully softened.
 
I'm going to have to try this annealing trick. I have tried to anneal it before, but I was definitely heating it above critical. I hadn't thought of keeping it below critical. Doh! :)

Thanks, guys!

Josh
 
Kevin Cashen said something about O-1 forming flat carbide plates that will squeak a drillbit if you allow it to form pearlite I forget the details, but that corroborates my experience with the transition zone between hardened blade and unquenched handle that I used to get with O-1 when I was forging it. I got around the problem by pre-drilling rivet holes at the time, now I use Aldo's 1095 and 1084, and i don't have those issues anymore. but I did buy a special straight flute drill specially designed for drilling hardened steel from Tracy Mickley just in case I do another scale tang knife in O-1

-Page
 
Just stick it overnight in vermiculite after you get done normalizing it, after forging. Use cobalt bits; no problem. (Heat it up again before you put it in the vermiculite.)
- Mitch
 
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Troop said:
Just stick it overnight in vermiculite after you get done normalizing it, after forging. Use cobalt bits; no problem. (Heat it up again before you put it in the vermiculite.)
- Mitch
Click to expand...

I tried that, and it failed spectacularly. :)

I wound up tossing the blade in the trash. I'll stick with simple carbon steels for forging now, and leave the O1 for stock removal projects.

Josh
 
JoshEarl said:
I tried that, and it failed spectacularly. :)

I wound up tossing the blade in the trash. I'll stick with simple carbon steels for forging now, and leave the O1 for stock removal projects.

Josh
Click to expand...


You probably got it over non magnetic before you stuck it in the vermiculite, didn't you? :)
 
Phillip certainly knows where I will go with this- any steel over .8% carbon could give you some real issues when cooled slowly from well above "critical", and stuffing it into a hot forge for the evening really should be avoided. I did all of these things for years myself, after all it is a very standard practice with knifemakers do it has to be correct... right? But when I actually saw what was happening to that carbon in excess of .8% I got a serious wakeup call.:eek: I also started to fully understand why so many guys were seeing benefits from odd heat treating practices that no other metal working fields use (the ones that didn't anneal that way).

Putting above .8% into solution will allow it to come out of solution where it prefers to be on slow cooling. It will prefer to group together in clusters, which will laugh at your drill bits, and it will prefer to have these family reunions in the grain boundaries which will lead to embrittlement problems, regardless of heat treatment, until you find a way to get it out of there.

P.S. steel with less than .8% carbon should handle the vermiculite just fine since it doesn't have extra carbon to cause trouble oustide of what is needed to make pearlite.
 
Obviously, the best way to anneal is with salts or an oven, but very frequently, I don't want to go to all that hassle, so I've learned how to anneal pretty well with the forge. It can be done. Most of the steels I use are .90 % carbon or higher, and I usually don't have problems. I even anneal M4, M2, and 440c in the forge. :cool:
 
So, then, what do you recommend someone with a charcoal forge do? I'm using hardwood charcoal but it's an outside forge so I can't consistently gauge temp by color. The Curie point is an awfully convenient temperature marker. I've had embrittlement issues with O1 and was frankly starting to get frustrated with the stuff.
 
jackrabbitslim said:
So, then, what do you recommend someone with a charcoal forge do? I'm using hardwood charcoal but it's an outside forge so I can't consistently gauge temp by color. The Curie point is an awfully convenient temperature marker. I've had embrittlement issues with O1 and was frankly starting to get frustrated with the stuff.
Click to expand...

If I were you I'd stick with a simpler steel, like 1084, until you get an oven.
 
Damn. I was afraid you'd say that. I already bought O1 and W1. I hate to have to set it aside until I can swing an oven. You stated in a previous post that you anneal pretty well in the forge but you also said you use a torch to anneal. What is your process? Do I need to shell out for a gas forge and thermocouple to make this work?
 
Phillip has also given a great tip for working with hypereutectoids (steels with more than .8% carbon) with even very simple tools. Here is where you can use a magnet in a truly useful way. Heat the steel for annealing without ever loosing magnetism. 1414F is just barely above the temperature where things will start to go into solution, and at that point only the pearlite will have an opportunity to begin to do this. Cycling the steel several times, being careful not to lose magnetism will allow you to break that carbon up in to little rounded particles, and be a great stress relief to boot.

For normalizing - well above critical is best for these steels, for annealing the lower temperatures will work best.

The W2 will work fine, the only problem you will face with O1 is keeping it at the proper temp long enough to get the most out of it in hardening with a charcoal forge. That being said many folks have been very happy with those results for some time now, so perhaps one can be happy and say "good enough".
 
jackrabbitslim said:
Damn. I was afraid you'd say that. I already bought O1 and W1. I hate to have to set it aside until I can swing an oven. You stated in a previous post that you anneal pretty well in the forge but you also said you use a torch to anneal. What is your process? Do I need to shell out for a gas forge and thermocouple to make this work?
Click to expand...

I'm really low-tech. I just heat mine to forging temp. after normalizing 3X, in my two burner propane forge. (The forging temp. is below critical). Then I put it in the vermiculite for at least 8 hours. I use a drill press set at the lowest speed that I can, and use cobalt bits; I don't have any trouble drilling out tang holes in 1/4" O-1. It sounds like you're getting it at least to critical if it's hardening up so much that you can't drill it after using the vermiculite.
- Mitch
 
Phillip Patton said:
You probably got it over non magnetic before you stuck it in the vermiculite, didn't you? :)
Click to expand...

Doh--yep. :) I did attempt to soften it by heating it under critical, but I only did it a couple of times, and I let it air cool on both occasions.

I think the blade went out with the trash today. I was sick of it taunting me. Very frustrating to have only 1/8" of steel standing between you and a really good blade, but there it was.

Maybe I'll do a little forging on a scrap and try to cycle it. I would really like to be able to forge O1 without worrying about drilling it...

Josh
 
JoshEarl said:
Doh--yep. :) I did attempt to soften it by heating it under critical, but I only did it a couple of times, and I let it air cool on both occasions.

I think the blade went out with the trash today. I was sick of it taunting me. Very frustrating to have only 1/8" of steel standing between you and a really good blade, but there it was.

Maybe I'll do a little forging on a scrap and try to cycle it. I would really like to be able to forge O1 without worrying about drilling it...

Josh
Click to expand...

Don't let it air cool if you want to anneal it.
 
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