Heat Treating O1 tool steel

[WorkHorse]

I have done a lot of research and I keep finding different point of views on hardening and tempering. I know you need between 1250 and 1300 degrees but how do you know when it reaches that point i know that's higher than magnetism. Plus I had thought about using a toaster oven to temper the knives at 400 degrees. Does anyone have any suggestions?

[AUBE]

Originally Posted by WorkHorse

I have done a lot of research and I keep finding different point of views on hardening and tempering. I know you need between 1250 and 1300 degrees but how do you know when it reaches that point i know that's higher than magnetism. Plus I had thought about using a toaster oven to temper the knives at 400 degrees. Does anyone have any suggestions?

I think you might be confusing the preheating temp with the austenitizing temp. O1 has to get hotter than 1300.

Theres a lot more to heat treating than most people realize, and I don't know how deep you want to get into it but heres a good starter page for you http://www.crucible.com/eselector/ge...eralpart2.html .

In a nutshell many makers heat it to non magnetic, then "get it a bit hotter", hold for about 5mins (don't overheat it!), then quench in oil, and temper between 400-450 depending on usage. As you can see its not a very scientific method, but if done right you can make some very usable blades.

How can u tell when its non magnetic? Pull it out of the forge for a minute and touch it to a magnet. Pay attention to what color the steel is when it turns non magnetic, and just get it a shade brighter than that.

Toaster ovens work but they are notorious for being inaccurate. Most people buy a thermometer(or two) to stick in the oven so you get an accurate reading. Sticking a pan of sand, or a chunk of larger steel in there works as a heat sink and keeps the temps from fluctuating as much.

If you want to really learn whats going on then reading texts on metallurgy is a good idea. I recommend "Metallurgy of Steel for Bladesmiths and Others who Heat Treat and Forge Steel". Its available free online.

[Crex]

AUBE is right. Plus O1 is a bit more difficult than other more simple hi-carbon steels like 1084. Unless you are very good with your understanding of your forge, can control it well and understand color differentials, O1 is better done in a controlled HT oven. It's great steel, one of my favorites, but to get it's full potential the oven is the way to go. Drawing the temper at 400 is low for O1 and it will still be a little too hard for most user knifeblades. Again, this is a temp control thing that requires some modicum of accuracy. If you are not good at modifying your toaster oven to better control the heat, you are not likely to get optimum results or even good quality repeatable results.
Reading and studying-up is definitely the way to go before attempting O1 and other alloy steels.....well even the simpler hi-carb steels too.

Magnets are a helpful indicator to let you know you are approaching the ball park in temps, but alloy steels are a bit more sophisticated players in this game. Need to go a little deeper in your research.

[Doug Lester]

I'm with Carl on this. I've messed with some of the higher alloy steels, 52100 in particular, and have had some good luck but I've come to the conclusion that it's much better to match the steel to the equipment that I have for heat treating and rely less on good fortune. The hypereutectic steels (that's steels above 77 points of carbon in them that form carbides in the austinetic state) can be a little tricky to heat treat. Get them too hot for too long and the grain growth can take off and you can increase the retained austinite.

Even though 1084 is above 77 points of carbon, the principle carbide formed is cementite (iron carbide) and it goes back into solution much easier that carbides of other metals and it's not as likely to form much retained austinite. Other good steels for more basic equipment would be some of the other 10XX series of steels or something like 5160 or 9260 or the W series of tool steels.

Doug

[WorkHorse]

Okay then I will hold off on using O1 for now I did get a leaf spring off of a old truck at my usual scrap yard. What if I heated it up past the magnetism point and tempered it using the method where you watch till it turns blue on the spine? I am using a propane gas forge.

[Doug Lester]

Heating with a torch is an iffy proposition. You might do better with buffering the temperature swings of a toaster oven you inserting the knife in a pan full of sand. You could also temper in an oil bath heated in an electric roaster. Of course there is also sweet talking the wife and using the kitchen oven. Whichever method monitor the temperature with a thermometer, not the dial setting.

Old leaf springs are still mystery metal and you will have to experiment with heat treatment until you find what works for that batch of springs. Also old springs often have stress cracks in them that will ruin a blade. It's far better to start off with a known steel though, if you have to go with mystery metal, old springs are probably the best source. At least you can be reasonably sure that they have enough carbon in them to quench harden.

Doug

[WorkHorse]

Thank you for the advise it is really appreciated. After reading and some thinking I am going to go with 1095 steel from Jantz Supply. I am going to take and try and find some coal and make a coal forge and go back to building one. The gas forge that I tried to build is not working at all to what I had hoped I don't think it is getting any where near hot enough. So, now I only have 2 more questions where can you get some coal and how does everyone cut there steel out if you do stock removal process? I have seen where people use hack saws, but is there a better way?

[metal99]

Just to give you an idea on oven tempering accuracy ill share my experience with you. I use my toaster oven for tempering my blades. I found that to keep a solid 400-425F temp range I had to have it set at 380f. My kitchen oven on the other hand, when I set it to 400F and watch my thermometer it goes from 350F all the way to 500F in a matter of seconds. Make sure you test out the oven with a thermometer before you stick a knife in it.

Another thing that may help you out would be to get some heat crayons from a welding shop.

I use a cut off wheel to rough out my blade then I finish it off with my belt sander. Some other options would be a metal cutting bandsaw or if you have the money a plasma cutter I wish I had one lol

Ohhh and I would stay away from 1095 until your very comfortable with heat treating. Go with 1084 it's the most user friendly and makes a fantastic knife.

[Crex]

I would recommend staying away from 1095 or the "W's" for now. You have a lot of learning to get under your belt and the best metals to begin with are as Doug mentoned....1084 or 5160. They will forgive a lot of beginner mistakes and still make a good knife. The higher carbon steels come with more exacting control needs. You can get "drops" at supension shops (car springs/muffler shops), and they can tell you what alloy steel they use. The drops are cut off pieces from where they make up the springs. If it's not 5160 or 6290 steel leave it there.
The 1084 will usually be cheaper than the 1095. CHeck out Aldo Bruno's "New Jersey Steel Baron" site for better prices. He sells quality steel.

While kitchen ovens will work....they do vary a lot as they cycle as stated above. Mostly due to the size of the interior chamber, lot of excess space to regulate. A toaster oven can be modified to work pretty well if you take the time to pull it apart and reinsulate the interior with K-wool or similar, use two oven thermomters and average out the heat setting (forget what the dial says).

There is no mention of a "Quench" step in your last post....???? Hope you are not leaving this step out. There are things to consider with quenching technique as well.
I'm with Doug on the temper draw with a torch, takes a lot of experience to get it right and on bigger blades it's a bit more than just difficult.

Not trying to be negative or dissuasive with your endeavors, but you seem to be bouncing around all over the page with your approach. I think you would be much better served and enjoy the whole process more with a more focused approach. Find a local knifemaker of good reputation and spend some time with him/her to learn to do the basics correctly.....even if it cost you some money for lessons up front, it will save you three times as much as experimenting on your own not to mention the frustration factor. There is a lot of applied science to knifemaking that must be learned to be successful. You didn't learn math on your own did you?
I hope you will continue with your pursuit, but highly recommend some shop time with experinece.

[cbsmith111]

People greatly underestimate hacksaws. I believe this is mostly due to stigma and bad experience from using poor saws, blades, and techniques. I use a hacksaw exclusively to cut out my profiles. No, it is not the easiest, quickest, or cleanest way, but it works just fine. It takes me about ten minutes to cut one out to within about 1/8" of the outline. You won't get these results with the $5.00 frames most people seem to buy. It will bend in half before you get enough tension on the blade for a good cut. Get a good high tension hacksaw. Not the kind with the wingnut straight back from the blade, but one that has a lever at the bottom that tensions the blade. You'll see what I mean if you look at them. This is the one I have and it is excellent

http://www.apexhandtools.com/brands/...c=037103809650

Also get some good bimetal blades and do a little research to determine which teeth per inch you need for the material you're cutting. Don't use a lot of force when you're cutting. Just nice smooth long strokes. Running the blade backwards lightly will create a notch to start your cut with. With practice you can even cut curves to some extent.

I realize that I kind of went off into left field over this, and that I probably look insane now. I also apologize if you are already proficient with them. I just have a soft spot for certain tools, and I feel this is one of the most misunderstood and underappreciate hand tools.

[Crex]

Yeah handtools, who'd a thought! I'm with you on the hacksaw CB, my hammer doesn't have a powercord either. I do have a heat tape on my big anvil for when it gets cooler this winter. Helps her warm up for the beatings. The horse linament just never seemed to help.

[Doug Lester]

Don't overlook the hand tools. Some times there is no substitute for a good file. They're not all that much slower than a grinder and they have a heck of a lot better control. Faster is not always better. I've also noted that a hacksaw will go through 1/4" stock pretty fast with a bimetal blade even of there's a little fire scale on the steel.

Doug

[WorkHorse]

Thank you for all the advice I will go with the 1084. I posted this so that I could learn more than what I have been reading for the last 3 months. Plus I haven't forgotten about the quenching I have getting some tongue quenching oil. Plus all the equipment I have is hand tools and blacksmithing tools I wanted to hand forge knives.