Heat treating?

M

mpj13

Joined
Oct 5, 2001
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108
I am about to heat treat my knife but before I do I would like to ask a few questions. I searched around and found bits and pieces but not all the info. My main question is are there any types of oils to stay away from? I have heard that most oils work fine, like car oil, what about corn or vegi oil, will these work also? Are there any adjustments in heat treating due to different oils? Another thing I am wondering once you heat it up and quench how long do you leave in oil? and do you have to temper as soon as your done quenching? I may have to heat one day and temper the next due to my schedule, but if it needs to be done right away I could wait until the week end. Thanks for any advice on the subject.
 
A question that is probably as important is - how much oil is rquired? Also, what shape of container should one use - a deep one or a wide and shallow one? How much distance is required below the blade and around the blade? Thanks.

Phil
 
I have 1084 and 1095 steel. The knife I have ready now is - 3 3/4" blade 4 1/4" handle OAL 8". I plan on making a small OAL of 4" and a blade of 10"-12" OAL. But right now just the 8" blade. Ditto PSO's questions too. Thanks.
 
I use olive oil for most of my oil quenching needs, since almost every steel I have that's oil quenching calls for a "light oil" and most veggie oils qualify. For 1095, when I'm doing differential heat treating, I use brine made from epsom salts and water. I usually use a two quart juice can for small to medium knives. The important thing is that you have enough room around the knife that your quench medium can circulate well. Don't put it closer to the bottom of your quench tank than 3" if you can avoid it, and ALWAYS preheat the medium first. Cold oil/brine will crack a blade easily. I usually heat to around 180-200. Basically I boil the brine and let it cool a little bit, and heat up oil until it's REALLY uncomfortable to touch. For larger blades, I usually edge quench them in a trough, but I have a large pipe set aside for sword-sized pieces for future use. For the steels you're using, I'd go with brine. It's more likely to fully harden, and boiling salt water is nowhere near as scary for us beginners as burning oil can be.
Hope this helps.
 
Originally posted by Osbourn
I use olive oil for most of my oil quenching needs, since almost every steel I have that's oil quenching calls for a "light oil" and most veggie oils qualify. For 1095, when I'm doing differential heat treating, I use brine made from epsom salts and water. I usually use a two quart juice can for small to medium knives. The important thing is that you have enough room around the knife that your quench medium can circulate well. Don't put it closer to the bottom of your quench tank than 3" if you can avoid it, and ALWAYS preheat the medium first. Cold oil/brine will crack a blade easily. I usually heat to around 180-200. Basically I boil the brine and let it cool a little bit, and heat up oil until it's REALLY uncomfortable to touch. For larger blades, I usually edge quench them in a trough, but I have a large pipe set aside for sword-sized pieces for future use. For the steels you're using, I'd go with brine. It's more likely to fully harden, and boiling salt water is nowhere near as scary for us beginners as burning oil can be.
Hope this helps.
Click to expand...

Thanks for the advice it really helps a lot when your starting out. What is the solution for brine, 1cut for every gal. ect. ect? Do you know what the benifits and differences are between oil and brine? One day I would like to make a sword, when you say you use a pipe how do you config it? Cut a strip out of the top and cap the ends? At the moment the best thing I have to use is a Wok it is pretty large and deep plus it has a built in burner for heating the quench solution. How long should I sink the steel to harden correctly? I just have nightmares of my firs knife coming apart when I try to quench it, but if it does I'll just start making another one. If Osbourn or anyone else can help with the current info it is much appreciated. Thanks.
 
MPJ13
The way I do it
Keep your steel in the oil until it's
cooled to the temp. of the oil at least.

I use 2 1/2" automotive exht. pipe at different lengths for
 different jobs with a flat plate welded to the bottom.
 as a stand and cap real cheap to do..

 if you heat it with a torch, heat evenly
and use a meat thermometer to check the temp.
I heat to about 135+deg F a good hot to warm feel.

 if you do it this way don't over fill,
the expansion and volume of the blade will take up space.
 with high carbon steels,most of them you can temper later,

 I differential temper using a water tube.

 with stainless, temper it right after..I use 154CM
 air quenched then temper , nitrogen soak, then re -temper
hope this helps some.
 
For my brine, I use "too much" of the salts. I keep adding them until they won't disolve any more. I wouldn't suggest using the wok, as you might get an uneven quench due to the unevenness of the container. It would overheat the quench fluid in the shallow areas and boil faster. I usually use a sheet metal trough that I fabricated for the purpose for edge quenching horizontally, but most of the time I prefer to quench point down, and that's what the pipe will be for. The only time that will be different is for clay heat treated japanese swords. I'll need a larger trough for them, but I haven't made one yet. I might cut a barrel in half for that. I still quench japanese knives point down.
To heat the quenchant, I usually just heat up a stainless rod to red and stir the fluid with it a few times. If I think of anything else useful I'll let you know.
 
Osbourn and Graymaker,
Thanks for all the info.

Osbourn,
If you can think of anything else please email me or post on this thread my address is mpj13@hotmail.com I would like to make trought of some sort for larger blades in the future, one day I want to be able to make a Katana, this is my favorite bladed weapon. I would also like to make some variations of Japanese and Chines weapons. When you make a Japanese knife do you like the American influenced point or the traditional rounded tip? One thing that I think would be very hard to do is make some kind of traditional, wrapped handle, I'm not even thinking about a sheath yet:eek:
 
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