Help with a couple HT recipes- AEB-L and 3v

JG Custom Metal Works

JG Custom Metal Works

Joined
Nov 27, 2013
Messages
1,626
I’ve been spending the last hour search the history on here for threads that I could have sworn were here at one time, but I’m not finding now. I’ve tried searching via Stacy’s “Bladeforums custom search engine” and the in forum search. No luck. One was either made by Devin Thomas or had his findings in it regarding heat treating methods if only having one heat treat oven. I also looked in the HT section and there doesn’t seem to be many stainless recipes in there.


Could you guys give me some feedback on my CPM-3v and AEB-L.




****My AEB-L recipe****


Place foil wrapped blade in oven at 1725f and soak for 20mins

Plate quench

Increase oven temp to 1965f. Once oven reaches temp, place blade in and soak for 10mins

Plate quench

Cryo in LN for 12 hrs

Temper at 375f for 2hrs two times for 62-63hrc/ temper at 350f for 63hrc





****My CPM-3V recipe****


Pre-heat foil-wrapped blades in oven at 1250f and soak for 10mins

Raise oven to 1550 and soak for 10mins

Raise oven to 1950 and soak for 30mins

Plate quench

Cryo in LN for 12hrs

Temper at 400f for 2hrs three times. 60-61hrc




Now, my main concern is with the 3v heat treat. Soaking at the three different temps would be leaving the blade in the oven for quite a long time. I think I remember reading somewhere that it wasn’t needed to do the preheat with 3v if you only have one oven. Is that correct? Would it be best to just go straight to 1550f and soak for 10mins and then ramp(while leaving the blade in during the ramp) to 1950f and soak for 30mins?


I’m using a Evenheat 22.5 KO with a TAP controller. I had been setting the starting temps 100f higher than the needed temp because when I open the door and put in cold blades, the temp drops 100f by the time I get the door shut. Then I start the firing schedule at the normal temp. For instance 1725f for AEB-L. Does that make sense?


Also, when having a knife in for its first temp soak, say at 1550f for 3v. I’ve just been leaving the blade in while it ramps up to the final temp of 1950f. Sometimes that takes up to 30mins or so. Then I let it soak at temp for the 30mins, at 1950f, which the recipe calls for. Is that how you guys do it?


Any critique you guys could give me on these recipients would be greatly appreciated.
 
Only thing I will comment on is AEBL does not need to soak in the LN. Once it stops bubbling you can pull it out.
 
Roman Landes Heat Treatment recomendation :

”Now this is what I would recommend for heat treat cpm 3v:


1st preheat: 500-600°C, equalize

2nd preheat:800-900°C, equalize

Autenize: 1060-1070°C, equalize, soak 30-35min

Quench in Oil preheated 60-80°C

Cryo: immediately after cleaning, minimum -80°C or lower soak 30min

1st Temper: 150°C equalize, soak 2hrs, quench in water

Cryo: immediately after temper

2nd Temper: 180-200°C equalize, soak 2hrs

should give you 60+ and a fine durable grain.”


RGDS Roman
 
I did a summary of the Thread linked above. If anyone sees an error please advise so I can correct.

This is DevinT's heat treat info for AEB-L

https://www.bladeforums.com/threads/how-to-heat-treat-aeb-l-in-the-home-shop.1353014/

Hoss highly recommend making 5 test coupons, heat the first one to 1900⁰F and plate quench, second to 1925⁰F, third one to 1950⁰F, 1975⁰F, 2000⁰F. This will give you a starting place for what temperature to use. Repeat this test with 5 new test coupons except do a sub-zero (freezer) or Dry Ice quench after the plate quench. With each set of test coupons measure the HRC and you should find a peak hardness at a specific temperature for your furnace.

It is also good to break each of the test coupons and see grain size and toughness differences. All furnaces are different, each will have a different soak time and or temperature required, even two ovens of the same make can be different. After determining correct temperature to use, then use below.

Soak blade at 1725ºF for 20 minutes, plate quench – this is called the “Pre-Quench”.

(Hoss and Larrin say it’s ok to wait until next day for 2nd step)

Second quench with only one oven set at 1950-2000⁰F (depending on results of test above). AFTER oven stabilizes at 1975F (per tests above), then place blade in oven and soak (austenitze) for 8 minutes. It’s not good for blade to be in oven the long period of time required for ramping up.

Dry ice quench right after plate quench, continuous cool down. With an extended cryo (LN) there will be some nano sized carbides that precipitate, slightly better wear resistance with a slight decrease in toughness. At this point expect 62 to 63 Rc.

Temper twice, first temper for 1 hour at 350F, 2nd temper for 2 hours – choose temperature based on Rc test prior to temper. Tempering at 350F doesn’t change Rc much at all. Each 25F increase in temper temp seems to drop 1 Rc point. Tempering at 375F seems to drop from 62 to 63 Rc to 61 to 62 Rc, and moving to 400F would expect to drop another point.

Final Rc post temper should be 60 to 61 Rc for best kitchen use. (some folks are reporting a Rc of 62 works good for a kitchen slicer)

DevinT says: For HT'ing without dry ice, Lower the quench temp to 1925⁰F, keep the soak time at temp to ten minutes, quench in oil or plate quench, faster is better, put it in your freezer (-5ºF) right after the quench, this will keep the RA down. Temper at 325-350ºF.

To anneal AEB-L wrap blades in foil, soak at 1350⁰F for 12 hours – does not require slow cooling. This is a very good condition to re-harden from. This is a simple sub-critical anneal to allow straightening before re-heat treating in cases of warpage. Once the sub-critical anneal is complete, ramp oven to 1725F, then place blade in oven for 20 minute soak. Remove blade, ramp oven to 1975F for final HT.
 
JTknives said:
Only thing I will comment on is AEBL does not need to soak in the LN. Once it stops bubbling you can pull it out.
Click to expand...

Is there any harm in leaving AEB-L in to soak? I guess not leaving it in as long means I can get it in to temper sooner. But is there any harm in not taking it immediately to temper, after hardening(with the short liquid nitrogen dunk in between)?

Thanks for your input.
 
Thanks for the input guys, I really appreciate it.

I guess one of the only questions I can think of at the moment is in regards to the 3v.

Do all of you do the first pre-heat stage at 1250f? If so, do you just leave the blade in the oven the entire time as it ramps up to the higher temps? That would be the easiest way to go for me as I could just make one firing schedule and let it go once I get the blade in at the first temp(1250f).

Or would it be better to take the blade out after each soak and wait for the oven to come back up to temp before I put it back in? That way it wouldn’t be held at the higher temps for as long.
 
JG Custom Metal Works said:
Thanks for the input guys, I really appreciate it.

I guess one of the only questions I can think of at the moment is in regards to the 3v.

Do all of you do the first pre-heat stage at 1250f? If so, do you just leave the blade in the oven the entire time as it ramps up to the higher temps? That would be the easiest way to go for me as I could just make one firing schedule and let it go once I get the blade in at the first temp(1250f).

Or would it be better to take the blade out after each soak and wait for the oven to come back up to temp before I put it back in? That way it wouldn’t be held at the higher temps for as long.
Click to expand...
I don’t do a preheat, I let the oven get up to temp, place the blade in, then when it equalizes, start your soak timer. This method has been recommended by a few different makers here!
 
I’ve been using 1950 for 3v, I need to try a few different temps, as quenched I think I’m hitting 62-63, I don’t have my notes in front of me. But toughness and edge retention is really good! I’m tempering to around 59.
 
rodriguez7 said:
I’ve been using 1950 for 3v, I need to try a few different temps, as quenched I think I’m hitting 62-63, I don’t have my notes in front of me. But toughness and edge retention is really good! I’m tempering to around 59.
Click to expand...

So let me get this straight, you just set your oven to 1950f. Once it reaches that temp, you let the oven soak at 1950f for 15-20mins and then put the blades in for a 30min soak?

You don’t even bother with putting the blades in at 1550f? Just go straight to 1950f for a 30min soak and then done, right? Am I understanding you correctly? Sorry to pester at you like this, but with heat treating, the devil is most certainly in the details. Thanks for taking the time to respond to my thread I really appreciate your input.

Does anyone else use this method?
 
JG Custom Metal Works said:
So let me get this straight, you just set your oven to 1950f. Once it reaches that temp, you let the oven soak at 1950f for 15-20mins and then put the blades in for a 30min soak?

You don’t even bother with putting the blades in at 1550f? Just go straight to 1950f for a 30min soak and then done, right? Am I understanding you correctly? Sorry to pester at you like this, but with heat treating, the devil is most certainly in the details. Thanks for taking the time to respond to my thread I really appreciate your input.

Does anyone else use this method?
Click to expand...
That’s the way I’ve been doing it! I had asked a very reliable source from here on the forums for some heat treat help a while back, and this is where he steered me! Not a pester, we have to start somewhere! There is another thread in this page, where Nathan the machinist explains a little on this. He suggests running the oven 100 degrees hotter, before you put the blades in. I usually test a blade to failure in my first test run batch, to see where I’m at! Good luck, let me know if you have any other questions.
 
rodriguez7 said:
That’s the way I’ve been doing it! I had asked a very reliable source from here on the forums for some heat treat help a while back, and this is where he steered me! Not a pester, we have to start somewhere! There is another thread in this page, where Nathan the machinist explains a little on this. He suggests running the oven 100 degrees hotter, before you put the blades in. I usually test a blade to failure in my first test run batch, to see where I’m at! Good luck, let me know if you have any other questions.
Click to expand...

The sad thing is, I’m not really “starting.” I’ve heat treated a good 10-15 blades of both 3v and aebl. The problem is, I’m always nitpicking my own work and HT recipes. These above recipes have worked well, they just kind of seem overly involved. I just wanted to see if I could make things a little easier on myself.

Oh I always run the oven 100f degrees hotter than when I start the cycle. Between opening the door and putting cold steel inside, it easily drops that 100f degrees. Once the blades are in, and the door is shit, then I start my firing schedule.

Thanks again for taking the time to contribute to my thread Rodriguez. I appreciate it.
 
JG Custom Metal Works said:
The sad thing is, I’m not really “starting.” I’ve heat treated a good 10-15 blades of both 3v and aebl. The problem is, I’m always nitpicking my own work and HT recipes. These above recipes have worked well, they just kind of seem overly involved. I just wanted to see if I could make things a little easier on myself.

Oh I always run the oven 100f degrees hotter than when I start the cycle. Between opening the door and putting cold steel inside, it easily drops that 100f degrees. Once the blades are in, and the door is shit, then I start my firing schedule.

Thanks again for taking the time to contribute to my thread Rodriguez. I appreciate it.
Click to expand...
No problem, I’m still learning, and ask a lot of questions myself! I’m still looking to refine 3v and 4v, but my results have been good so far!
 
rodriguez7 said:
No problem, I’m still learning, and ask a lot of questions myself! I’m still looking to refine 3v and 4v, but my results have been good so far!
Click to expand...

Have you tried using the 1550f preheat ever? It’s kind of hard to determine the usefulness of preheats without doing coupons to break in half. High hardness numbers can be attained with the 1950f soak and quench from my understanding.

That being said, having just one oven and trying all three temps(1250f preheat, 1550f preheat, and final 1950f soak) seems like it could have negative effects from the prolonged exposure to excessive heat. From my guess, the blade(s) would be at 1250f or above for around an hour and a half total with all the time it takes to ramp up to temp.

When setting the ramp rate temp, IIRC I set it to 9999 which is the highest it can go. That is basically what Evenheat suggests you to do to ramp up as fast as possible. It would seem that the coils get to the hottest temp possible while ramping up to higher temps. With the blades being just a few inches from the coils, I can’t help but wonder what effect those hotter temps may have. It would be nice to get some feedback on that theory though. The heat treating section/sticky has a bunch of really good info in it, but it seems like it doesn’t have a lot of info about heat treating stainless steels or heat treating with ovens.
 
If you're referring to AEB-L HT, the blade isn't in oven during ramp up, only during HT itself. The purpose of the 1725F soak seems to be grain refinement. Using this technique I get an extra point or so of hardness.
 
JG Custom Metal Works said:
Have you tried using the 1550f preheat ever? It’s kind of hard to determine the usefulness of preheats without doing coupons to break in half. High hardness numbers can be attained with the 1950f soak and quench from my understanding.

That being said, having just one oven and trying all three temps(1250f preheat, 1550f preheat, and final 1950f soak) seems like it could have negative effects from the prolonged exposure to excessive heat. From my guess, the blade(s) would be at 1250f or above for around an hour and a half total with all the time it takes to ramp up to temp.

When setting the ramp rate temp, IIRC I set it to 9999 which is the highest it can go. That is basically what Evenheat suggests you to do to ramp up as fast as possible. It would seem that the coils get to the hottest temp possible while ramping up to higher temps. With the blades being just a few inches from the coils, I can’t help but wonder what effect those hotter temps may have. It would be nice to get some feedback on that theory though. The heat treating section/sticky has a bunch of really good info in it, but it seems like it doesn’t have a lot of info about heat treating stainless steels or heat treating with ovens.
Click to expand...
I haven’t tried it, I have more testing to do. What I’m doing has been suggested by Nathan Carothers and bluntcut from this forum, in my opinion, they are the go to as far as heat treat is concerned. Nathan has talked about the evenheat exposed coils, that’s why he recommends this method, something about un even heating, and spikes in heat! He’s much more intelligent than I am! I’ve had really good results with this, testing to destruction! I know one blade I made in 3v, .20 thick has taken over 50 side impacts with a 1.5 lb sledge hammer! Which I would say is pretty dam tough. It’s the only steel I’ve tested, able to take that kind of abuse. Even 8670 clay coated couldn’t handle that. But I’ve been running 3v at around 58-59 rc. I need to test at 60 and see what I get.
 
I think it was Nathan C who mentioned the NON necessity of pre heats for us knife makers. The practice of pre heating is for items that have complex cross sections, of which a knife is not. I can't think of a metallurgical reason why a pre-heat would make a better blade than one that was simply placed in the oven that has settled at its austenitizing temperature and soaked properly.
 
I spoke with ol Nate himself and I’m gonna try out the 3v single heat heat treat tonight. What do you guys think then, 30min soak at 1950f?
 
You must log in or register to reply here.
Back
Top