Porblem heat treating O-1

bikermikearchery

bikermikearchery

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Jan 18, 2007
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I'm not a new knife maker by any means. I have been using recycled/junk metal for making knives for many many years and heat treating with charcoal and a hand bellows with good results.
This year I decided to invest in good quality steel. bought New O-1 steel and built a miny gas forge. So yesterday I attempted to heat treat my first batch of knives in the gas forge. This is also the first time I have ever used a thermometer when I heated my quench oil. 140 degrees.
Brought the steel to a nice bright orange color held it there for 10 minuets. I have a magnet on a string between the forge and the oil. After 10 minuets soak time, in to the oil.
I did 5 knives. but I cooled the oil to 140 degrees by adding more between each knife. Went in to the oven at 400 degrees for an hour,and cooled 3 times.
When I started to do the finish I checked with a file and it cut like I hadn't done a thing to them. In fact I have a piece of spring stock that I was annealing that air hardened harder.
So today I went out and retried the heat treating. made sure I was faster from the forge to the oil, and used a larger can of oil. I checked with a file Right out of the oil, before tempering, and the damn stuff is still soft.

OK what have I missed. Is O-1 that picky. I have missed my mark before BUT never twice.
 
BRIGHT ORANGE? That's like 1800'F ish isn't it? And if so, the austenizing temperature is 1500'F which might have been your problem. Too much heat which caused it not to harden. Try 1500'F which is well i'm sure you can find a color chart.

A2 tool steel austenizes at a bright orange or 1725-1800'F.

Try a nice even cherry red next time and then quench. Forget the 10 minute dealy. Too long without a protective layer or atmosphere.

Try warm vegetable oil instead of any toxic motor oil. I have always had great results with that. You can even do an edge quench if you'd like!

But definately too high of heat I believe.
 
Leu Custom said:
I think I may be dumb here to say this, but A) you shouldn't FORGE 01 or any tool steel for that matter. By Forging it, you change the steels properties and well, technically it's not 01 anymore. 10 minutes at heat i'm guessing burned a hell of alot of carbon out i'm guessing.

I have had success heating the blade to a nice cherry red or heck even orange throughout and just quenching in warm vegetable oil and using a rocking/agitating motion till the blade is nice and well okay to the touch. Tested it with a file and it skipped right off the blade and that was done with a MAPP/Oxygen torch.

It is possible that you took it way over the 1500 degrees you're suppose to heat treat 01 at. If you go way over, it won't harden properly or at all I have heard.

I mainly use A2 tool steel...but I think you basically either took it up too high for too long. I don't think it has anything to do with your quench at all.

01 should be heated for about 5 minutes at heat should be all you need. Try that next time and if possible, try to keep it around 1500'F for no more than 5 minutes and then have your quench tank/device close by.

Ideally 01, should be heat treated in a kiln, but if you don't have that, that is my next best answer for you.

Try vegetable OIL. it's not toxic and won't flare up (unless possibly you have a lot of it)...i've even taken a MAPP torch directly to it and nothing happened. Get the blade to a nice even color and quench. No need for the 10 minute crazy in an gas forge.
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You're gonna get slapped for those comments, sir....I am having visions of Thor.......or perhaps Kevin Cashen.......flyng down from Asgard.....or Michigan, as the case may be........ to smite you with his hammer.:p:D
 
perhaps that is why i changed it, but you had posted what I had said before I rethought my thoughts :D
 
There is a post in the tutorial or newbie section on soaking O-1 where it was soaked for 5 hours and broken and tested. the steel shone a very fine grain and no detrimental affect.. It was not recommended just an experiment.

1450 to 1550 degrees is right on the package and I totally missed it. I had no idea that I could go to hot.
 
O-1 should be austenized at between 1450 and 1500 degrees F. Steel becomes non-magnetic at 1414 degrees F, so a magnet alone will not get you the correct temperature. I suggest getting a pyrometer. The ten minumte soak time should be fine, assuming that you are at the proper temperature.

These may help.

HTG-p-278_O1.jpg


HTG-p-279_O1.jpg

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I recently had the same problem. I used a kiln/heat treat oven. My temp was 1450 for 10 minutes and then quenched in oil..It did not harden !! I tried it 3 times...Finally I heated the edge with a torch and quenched it in the oil again and it finally hardened..I am suspecting that it is taking too long to get from the oven to the oil ??!!:eek:
 
rocketmann said:
I recently had the same problem. I used a kiln/heat treat oven. My temp was 1450 for 10 minutes and then quenched in oil..It did not harden !! I tried it 3 times...Finally I heated the edge with a torch and quenched it in the oil again and it finally hardened..I am suspecting that it is taking too long to get from the oven to the oil ??!!:eek:
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Did you try turning up your oven up 50-100 degrees?
 
Over heating will still get it hard but with very large grain size.Either you haven't heated high enough or small chance of it being the wrong steel. "orange " is a very vague term !! It's spelled 'pyrometer' !!
 
Listen to Mete'. If you had it at an orange heat, it's going to harden. If you had no decarb protection in your soak, that could be the problem. You may have achieved hardness, under the layer of decarb that the file never struck. Years back I had the same problem the first time I gave 01 a real soak at 1500o for fifteen minutes. I file checked, and the file cut it easily after quench. Then I filed some more and found it very hard under the surface a ways. Afterwards I started using PBC powder to prevent decarb, and have had no problem since. In order to HT 01 even near correct, you do need heat control, and a way to monitor temp. Just my opinion, but I think the magnet method of judgeing quench heat is way over rated, and causes more problems than using color to go by. I think colors can be relatively accurate, but the lighting needs to be the same every time you HT. That is not always easy. An accurate pyrometer will take the guess work out of the equation. And use some method of decarb protection, or leave enough steel to grind the decarb away.
 
LRB said:
And use some method of decarb protection, or leave enough steel to grind the decarb away.
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In my vast experience of HTing 4, O-1 blades I used a thin coat of satanite dried onto each blade for the HT. Some will flake off into your oil but I had almost no decarb.
 
No slapping, I am actually a pretty nice guy, or at least a push over when it comes to confrontation. I rarely have any reason to focus on what a person says that may be incorrect, unless they state is as fact without providing supporting data to show why conventional wisdom is wrong. When a person is honestly working off the best information that they have, the only decent thing for me to do is offer them some more information.

You cannot go too high for hardenability, in fact it is one of the quickest ways to increase hardenability. Higher temperatures dissolve more carbides, thus putting more carbon into solution and eliminating more points of nucleation for the pearlitic transformation, and eventually increases grain size which will also increase hardening for many of the same reasons. The down side is that large grain is very weak and putting too much carbon into solution will encourage retained austenite. But I believe we can safely eliminate too high a temperature.

Of course I highly recommend an actual quenching oil for the quenching operation, after we are not cooking french fries, nor are we lubing our truck, we are quenching... But that being said, O-1 has such a deep hardening curve that you should be able notice a serious increase in hardness regardless of what liquid you put it into. As has been pointed out, even cooling it in air will show an increase in hardness so even these silly glops and goos that too many play with should show some increase in hardness. So I believe we can eliminate the speed of the quench.

Tests that I am finishing up right now involving soaks at 1414F (Currie point) and various soak times, show that a file will read some hardening even with temperatures 36 degrees below the minimum and virtually no soak at all; later performance and Rockwell readings are a whole different story and temperig will be a fun adventure;). So as long as you are observing decalescence and going beyond it, I think we can eliminate the soak time as well.

Now the only things we have left are insufficient austenitizing temperature or decarb. Either you are not getting it to at least 1375F or you are cooking the carbon out of the steel for several thousanths. I am a huge proponent of soaking but not if all you have is a coal or gas forge, not only is it very difficult to maintain temperature, it is very conducive to decarburization. The better thing to do with these tools, and that steel, is to watch for the shadows to leave the steel and then quench it and settle for having undissolved carbides. The best thing to do, however would be to go with a steel that is a better match for these tools, 1084 needs little soak time and can be quenched from a range of temperatures.

You can test to see if it is decarb by either grinding a few thousandths off the dissapointing piece and then checking it again, or by running a few sample pieces at the same time that you quench after much shorter time intervals.
 
If by chance you are ordering your O1 from enco they goof on occasion. In my last batch there was one piece that could not be hardened either. I noticed on the bar that it was stamped LC in black. That means it is low carbon. My fault for not looking at the label. It was just a warehouse goof up.
 
kinda sounds like what I said in the post by posted of me blabbing on by jmd61 was a bit true sorta kinda, not really :D :) Thanks for clearing that up Kevin. :D
 
mete said:
Over heating will still get it hard but with very large grain size.Either you haven't heated high enough or small chance of it being the wrong steel.
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Thank you Mete,

This stuff is physics not magic.

I kind of lean toward the decarb problem thing. I say it because I've done it. :eek:

I've gotten to the point that I don't even check hardness until I get the few thousandths I allow for decarb off and down to 220 grit or so. Just gotta trust you did it right and got the right steel.

chiger,
 
In my case I tried 1450, 1500 & 1550 each with a 10 min soak. I also tested a small scrap of the same bar of 01 which hardened just fine !!??!! The scrap piece was the full 1/8" thick but the edge of my blade was ground down to 1/16"..I am suspecting that the edge is cooling down too much between the oven and the quench tank....It only takes me about a second or two to make the transfer to the oil...I think that I will try to speed up the transfer..:confused:
 
Don't you still have time to quench it if it stays above ummmm 900-1000 degrees F ? Haven't played with much 01, but heck i've been WAAAY slower than 1-2 seconds doing an edge quench and the steel still got hard like crazy....harder than my Nicholson files :D

This is why people use Air-Hardening steels! Take it out of the kiln and let it quench either in still air or plates! No oil, no mess! :)
 
I take my edge to the finished thickness before sharpening. Never a problem, but I use PBC.
 
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