O1 Heat Treat

Big Smitty

Big Smitty

Joined
Aug 30, 2007
Messages
509
I am just starting into knife making and need a liittle help. I have a blade that I made by the stock removal method since I do not have a forge yet. It is 8" overall with about a 4 1/2" blade that is 1/8th" thick. Can you guys tell me how to heat treat it. My available resources are a mapp gas torch, a Oxy Accetaline torch kit I use to do heating and A/C brazing work, a gas grill, a charcoal grill, a kitchen oven, a pack of matches, a bic lighter and a bunch of determination. Your help and direction is appreciated.
 
Don't fret...I'll help ya out. Realize that I am also a noob, and just did my first heatreat today. This is what I used: Charcoal BBQ, Lump charcoal, propane torch to start charcoal, hairdryer with 3"x24" vent pipe attached for fanning, fireplace tongs, welding gloves, 12" mud pan for quenching, kitchen stove, and a telescoping magnet. All either on hand or dirt cheap!!! My blade is of about the same size as yours, and of O-1. It hardened up nicely: a file now just slides of the edge. I've already cut myself too :eek: I used the following resourses:
http://www.knives.com/heatreat.html
http://www.knife-making-supplies.net/cheap-knife-tutorial.html
http://www.knifenetwork.com/workshop/tut_heat_burnett.shtml
Good luck!
 
Make sure you heat it evenly and check for warping before you quench it, thin blades can be the devil that way.
 
O1 needs a soak at temp. Your target temp is 1500.

http://www.blksmth.com/images/large_size/Color Chart3.jpg
Color%20Chart3.jpg


This heat scale is from

http://www.blksmth.com/heat_colors.htm

Going from color picts on the internet ain't the best. For your reference, it will probably go nonmagnetic somewhere around 1400.

You'll want to obtain an even temp without overheating your edge or the tip and maintain that temp for at least a few minutes. If you have spheroid annealed O1 (most is) all your carbon is tied up with your alloying agents for ease of machining. You need to give it time to dissolve in the steel for the O1 to perform well. Otherwise, even though the hard spots will skate a file, the blade won't hold an edge.
 
If you insist on using a torch heat only the spine and let the heat spread from there .Keep the torch moving .You want to go about 100 F above the magnetic point and try to hold at temperature for a while.
 
Use the Oxy acet torch, the other will probably not be hot enough to get even heat. Check for non-magnetic and watch color. get as even as possible and quench in a light Oil. Veg oil or used trans fluid will work fine. the oil needs to be heated a little befor hand to about 125 (very warm on your finger). have a pan larger enough (bigger then 8" to quench the entire blade edge down at one time. Hold the back of blade with vice grips and lower into quench (can be exciting). When fully quenched clean really well and put in over at 400 F fo 1hr, best to cool and retemper in over 2 more times. It may not be perfect but with O1 you should end up with a good cutter. Email if you need more info I do work with O1 all the time.
 
Guys, is it truly important to give the blade time to cool down slowly after the initial time to temp nose has been met with the quench? I read that the martensite formation needs a slow cool (about 15 minutes) from about 950F to just hand-holdable temp before tempering. I've been doing it this way and it seems to work just fine, but I don't know if I'm just doing hoodoo voodoo or actually helping the process:confused:

Regards,

Dave
 
I have not seen anything like that, to get it right you heat to 1450-1500 soak (I have been doing 8 minutes but that I think is too long) then you quench but removed the blade pretty quick after the quench and let it air cool?? I just keep putting blades in the quench to keep them warm and then clean and into the oven.
 
Patrickknives said:
I have not seen anything like that, to get it right you heat to 1450-1500 soak (I have been doing 8 minutes but that I think is too long) then you quench but removed the blade pretty quick after the quench and let it air cool?? I just keep putting blades in the quench to keep them warm and then clean and into the oven.
Click to expand...

I'll dig around and see if I can find the site. The guy seemed to know his stuff, but as ignorant as I am it could have been total crap. I'd rather not spend 15 minutes holding a knife in tongs to air cool it after the quench if it's just hokum. Paging Mr. Cashen:)

Thanks for the feedback Patrick,

Dave
 
I guess you're talking about an interupted quench but you really don't need that . The oil should be about 140 F, quench and keep in the oil until the blade gets to oil temperature .Then temper for two hours.Before temper wash off the oil ! Set kitchen oven to 400 F .Using a brick or baking stone makes temperature more uniform.
 
Ehhh Mete, that must be what he was talking about. Under what circumstances (or steel type) would an interrupted quench be helpful? I could swear the writer was referring specifically to 01, but my memory bucket overfloweth sometimes. Thanks!

Edit: Would it help if I hold the knife towards the north while it's cooling;)

Dave
 
Thanks! Good info. I have done well on the knife to this point and do not want to mess it up on the heat treat. From your input I am wondering if the soak is critical? Or, do I just get it to non magnetic and then quench. Someone recommended getting a piece of black iron pipe and cutting a hole in it for the mapp gass torch to use as a improvised furnace. No insulation or anything just a way to reflect the heat back to the blade. This makes sense to me so I think I will try it. Thanks for all the input.
 
from 950F to 450F is no mans land (unless you are going for the dreaded "B'" word) if you want good martensite don't hang around there. Do a thorough soak, quench to around 130F and temper immediately. If you want to approximate a marquench quench to 400F and then allow to cool in air, and then temper immediately
 
Anything you can do to direct the heat will help, if you can get 4-5 firebricks you can make a little forge area to hold the heat in and that will help with the soak. The spec is sent has the soak at 1200 which you can probably hold without too much trouble 1/2 hour per inch. for 1/8 that come out to 3+ minutes. I do not think you can mess up the HT enough by following these instruction that you will be able to see a differance unless you have another blade to test side by side, the most important is the temper. If that is not right it will be very brittle, but its easy 400 f in the oven for 2 hours. good luck
 
i have a blade that is just about done, also in O1, and am glad to see some more info on it. the wrapper the steel came in pretty much says the the same thing you guys all say. heat to 1450, quench in warm oil, and temper at the temp that you want the final Rc hardness you want...
 
Patrick ,that 1200 F "soak" is actually a preheat and meant more for large pieces. Properly "soak" means at the austenitizing temperature and it dissolves the carbides.
 
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