Heat treat 15n20 - procedure

How long of a temper? I just did a smaller .12 blade last night at 300 for 90 min let it cool to room temp then again at 400 for 90 min. Just a hidden tang hunter/utility
 
valknut said:
How long of a temper? I just did a smaller .12 blade last night at 300 for 90 min let it cool to room temp then again at 400 for 90 min. Just a hidden tang hunter/utility
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Should be fine. It’s a pretty simple steel. I do 2h tempers out of habit, but I think 1h to 90 minutes per temper is fine for 15n20.
 
I had been using our kitchen oven to temper my 15n20 and it gave pretty consistent temperatures and good results. I wanted to move everything to the shop, so, I bought a toaster oven and started using it. The problem I found with that is that the temperature fluctuates 20 degrees in either direction. How much could I be losing on the hardness scale with that type of temperature fluctuation? I am currently setting the toaster oven at 335-340* f.
Hope I'm not derailing, if so, let me know and I'll start a new thread.
Thanks,
 
DanF said:
I had been using our kitchen oven to temper my 15n20 and it gave pretty consistent temperatures and good results. I wanted to move everything to the shop, so, I bought a toaster oven and started using it. The problem I found with that is that the temperature fluctuates 20 degrees in either direction. How much could I be losing on the hardness scale with that type of temperature fluctuation? I am currently setting the toaster oven at 335-340* f.
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I don't have an answer, but maybe there's a way to have a heat sink in there to avoid bigger temperature fluctuations? I use my kitchen oven yet leave all my cast iron pans and griddles in there and let it equilibrate a while before tempering a knife. I check a separate oven thermometer that I put in there and it barely changes. It could be that a toaster oven is harder to keep stable just due to the small size and closeness of the heating elements to everything inside, but that's just guessing on my part.
 
The problem with toaster ovens is there temp control is a simple heat sensitive contacts. And I'm guessing it takes a swing of 20deg on both ends to trigger the on and off. If I had to use a toser oven I would wire it with a pid and SSR and remove the cheep contacts.
 
JTknives said:
The problem with toaster ovens is there temp control is a simple heat sensitive contacts. And I'm guessing it takes a swing of 20deg on both ends to trigger the on and off. If I had to use a toser oven I would wire it with a pid and SSR and remove the cheep contacts.
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And then I could re-use the PID and SSR (maybe), when I get the time to build a kiln.
Thanks JT.
 
Yep no reasion to waste them.
 
DanF said:
I had been using our kitchen oven to temper my 15n20 and it gave pretty consistent temperatures and good results. I wanted to move everything to the shop, so, I bought a toaster oven and started using it. The problem I found with that is that the temperature fluctuates 20 degrees in either direction. How much could I be losing on the hardness scale with that type of temperature fluctuation? I am currently setting the toaster oven at 335-340* f.
Hope I'm not derailing, if so, let me know and I'll start a new thread.
Thanks,
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As a rough reference, 25f is about one Rc point in most simple steels.
 
How about heat treating 15N20 in a forge? Is soaking at a precise temperature for a certain amount of time before quenching essential? If so, is double or triple quenching an alternate way to obtain the desired results?
 
David, this is a three year old discussion.

To answer your question, 15N20 should be HTed in a HT oven. The soak time is needed, and exact temperature is pretty critical.
 
Stacy E. Apelt - Bladesmith said:
David, this is a three year old discussion.
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I know, but I believe there is practical utility of asking an unasked question in an old thread, because the thread is still publicly viewable, and thus still functions as a research resource.

To answer your question, 15N20 should be HTed in a HT oven. The soak time is needed, and exact temperature is pretty critical.
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Thank you. Now anyone who Googles "15N20 heat treat procedure" and finds this thread will have the answer to this question as well, and not need to start a new topic. :)
 
I know this is an old post but I heat treat a crap ton of 15n20. I have not seen any advantage in soaking 15n20 for any extended amount of time. It needs to be properly soaked and up to temp but I don’t think it needs X soak time like other steels. It heat treats so easily that Damascus made from it will have a tendency to air harden as it cools. Hardness is affected by overheating. It likes low austenite temps in the 1460-1480 range. The hotter you get it the softer it will come out. It will easily hit 66rc if you hit the temp right. I do give it a little soak in the oven but if I was using a forge I dont think I would risk over heating it trying to soak it for 5min. I would run it in and out till you hit non magnetic and give it another few passes and then quench. It is a very easy steel to heat treat and in my opinion on of the best beginner steels.

After you quench I pull the blade and hit it with an ir temp gun. If it’s under 400° then I slam it between quench plates. It does not mater how bowed it is. If the temp is 300-400° the plates will straighten it amazingly well.
 
I do roughly the same, but I have found that as long as it is below 800°F it is good to go in the quench plates. Once past the pearlite nose at 1000°F the steel is 100% rubbery austenite. This is very easily straightened or bent. The quench plates make sure that it is straight. Once the blade is below the Mf around 200°F the stiffness has set in and it can be removed from the plates. Here is a good TTT chart:
2-Isothermal-%E2%80%93-Transformation-Diagram-for-a-1080-Eutectoid-Steel.jpg
 
Don't mean to resurrect an old thread but lots of good information here. One question I do have is in regards to the quench plates. Is there any particular size/thickness I should look at? I will be mostly doing kitchen cutlery in 15n20. I
Thanks.
 
While I haven't tried it yet, a respected knifemaker and member of our local knifemaking club (the 5160 Club in Eugene, OR) claims that he skips the Parks 50 and goes straight to aluminum quench plates for his thinner 15N20 kitchen knives. And I believe him after ruining more than a couple drill bits trying to drill through tangs after forging out a damascus blade where I use 1080/15N20. The drill bit would start the hole, then hit hard steel which I was told was the 15N20, which can air harden in thinner sections.
 
Dopic1 said:
Don't mean to resurrect an old thread but lots of good information here. One question I do have is in regards to the quench plates. Is there any particular size/thickness I should look at? I will be mostly doing kitchen cutlery in 15n20. I
Thanks.
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I use 1" thick aluminum quench plates mounted in a quick release vise to quench AEB-L. When I read the posts above by Stacy and JT in the summer, I started using this setup for straightening carbon steel blades after oil quenching as well. I mostly use AEB-L and have only used it on three kitchen knives so far, but they all came out perfectly straight. Prior to that, I always had warps, so I am going to keep using this method.

If you think you might want to heat treat stainless at some point, I would recommend aluminum plates, the thicker the better. One inch thick has worked well for me, but I am just a hobbyist. For straightening after oil or water quenching, I bet you could get away with thinner material, or even angle iron as long as it is straight enough.
 
Hubert S. said:
I use 1" thick aluminum quench plates mounted in a quick release vise to quench AEB-L. When I read the posts above by Stacy and JT in the summer, I started using this setup for straightening carbon steel blades after oil quenching as well. I mostly use AEB-L and have only used it on three kitchen knives so far, but they all came out perfectly straight. Prior to that, I always had warps, so I am going to keep using this method.

If you think you might want to heat treat stainless at some point, I would recommend aluminum plates, the thicker the better. One inch thick has worked well for me, but I am just a hobbyist. For straightening after oil or water quenching, I bet you could get away with thinner material, or even angle iron as long as it is straight enough.
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Thanks for the information, I'm a hobbyist as well doing mostly carbon blades. I just recently retired and would like to try AEB-L and some stainless in the future. I was thinking the one inch plates and what you said makes sense, thanks.
 
weo said:
While I haven't tried it yet, a respected knifemaker and member of our local knifemaking club (the 5160 Club in Eugene, OR) claims that he skips the Parks 50 and goes straight to aluminum quench plates for his thinner 15N20 kitchen knives. And I believe him after ruining more than a couple drill bits trying to drill through tangs after forging out a damascus blade where I use 1080/15N20. The drill bit would start the hole, then hit hard steel which I was told was the 15N20, which can air harden in thinner sections.
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I have tested this in the past because I had heard the same thing. But it’s false to some extent. Yes it gets hard but not quenched in oil hard. I can’t remember exactly the hardness but I want to say it was in the mid 50s but under 60 for sure. But it was no where near what a proper oil will get it. The issue is that you need thin 15n20 to get those numbers and that’s more of a sword hardness not what you want in a kitchen knife. But steel in the 40+rc will be hard to drill. Hell 15n20 comes heat treated at 42-43rc and can be hard for some people to drill. With a slow speed and tons of coolant it’s not to bad. But you get into the 50rc range and forget about normal twist drills. I will do another test when I’m doing 15n20 again to get an actual number for plate quenched.
 
JTknives said:
I will do another test when I’m doing 15n20 again to get an actual number for plate quenched.
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Thanks JT, I'd love to see what you get.
Out of curiosity, how thick of a piece is needed to do an accurate rockwell test?
 
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