How to Heat Treat AEB-L in the Home Shop

Thanks Devin. I have been using this for AEB-L since you shared a few years ago and it is working out very well for me.
 
Thanks Hoss, For taking the time to explain your process. I will be using some of the AEB-L in the near future.

Bing
Merry Christmas
 
Thanks again Hoss. Does anyone know if there would be any advantage to a subzero treatment after the prequench and before the main quench?
 
Hoss: Thank you for taking time to share your knowledge. Even though this is the first I'd ever heard of using 2 quenches with AEB-L (or any SS), BUT since Stacy says "good info" I'm accepting it as the way to go.

I've been using Sandvik steels, but they have got HARD to get, and impossible in less than .098". I'm making the change to AEB-L, so am VERY interested in learning about HT'ing. I've HT'ed a couple of AEB-L blades and have not got as hard as I wished - only about 58-59 Rc from quench. I'm thinking I need a higher temperature. I'm using an Evenheat oven.

Sandvik says do not re-heat treat, but I suspect the 1725ºF pre-quench is low enough it isn't the same as re-HT'ing from 1975ºF?

Hoss, Stacy, others: Now, let me make sure I've got this all straight when using only 1 oven (all blades individually wrapped in SS foil). Please read the following and comment where I might be mis-understanding things.

For first quench set heat oven to 1725ºF and allow to stabilize, place blade/s in oven and soak for 20 minutes AFTER oven gets back to 1725ºF). Plate quench leaving blades sealed inside SS foil. If there are 4 blades, it will be ok to remove blade 1, plate quench, lay aside at room temperature. Remove blade 2, plate quench, repeat process for other 2 blades. This would have first blade soaked for 20 minutes with last blade a 25 minute soak. Is that ok?

Set oven temp to 1950-1975ºF (depending on temp determined with 5 coupon test - let's say 1975ºF) - allow to stabilize at 1975ºF. Place all 4 blades in oven at temp, allow oven to come to 1975ºF, then time soak for 8 minutes. Remove blade 1, plate quench, remove from SS foil and place in dry ice slurry.

Remove blade 2, plate quench, remove from SS foil and place in dry ice slurry (-95ºF).

Repeat for blade 3 and 4. This would have first blade soaked for 8 minutes with last blade a 12-15 minute soak depending on time required to process each blade. Is that ok? OR - am I limited to processing one blade at a time to exact soak times?

Allow blades to soak in dry ice slurry for 1 hr from time last blade when in dry ice. (since this is not cyro is a full hour required? OR - would 30 minutes be enough?)

You didn't mention tempering portion of HT - 2 hr at 350ºF?

Again, Hoss - THANK YOU for sharing your knowledge.

Ken H>
 
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Thank for such a great info. Never heard about the prequenching in high Cr steel before... Would steel like CPM-3V could be benefit from these kind of thing?
 
I am looking forward to the answer to Ken's question. I have been doing quite a bit of AEB-L using the recipe from Alpha with the lower temp and longer hold time. Results have been good but I realize Devin is an acknowledged expert on AEB-L. I only have one oven ad well so Ken's question is pertinent for me as well.
 
Thank you so much for posting that info on HT for AEBL. You've verified something I've been tossing around in my mind for some time now.
 
Hoss, just so we have an idea of the ideal setup, how many ovens are you using for the total process including the temper cycles? Are you using the same oven for the 1725F pre-quench cycle and the final austenizing step and a third one for tempering or do you have 4? And another big thanks from me for posting this info. :D
 
This info should also be helpful and will answer a couple of the above questions.

Soak times

Thickness, mm Thickness, in Time, minutes
2.5 --- 0.100 ---5
3.0 --- 0.118 --- 6
3.25 --- 0.128 --- 7
3.5 --- 0.138 ---8
3.75 --- 0.148 ----10
4.0 --- 0.157 --- 12
4.9 --- 0.192 ----25


Quenching

Quench as rapidly as possible. For optimal results 600°C (1110°F) should be reached within 2 minutes or less. (Sandvic recommends oil quench where possible)


Deep freezing

The material only needs to reach the desired deep freezing temperature, no soaking-time is required.

Tempering

Hardness Temperature
Tempering (2 hours)
62 HRC 175°C (345°F)
60 HRC 225°C (435°F)
58 HRC 350°C (660°F)
 
So far I have had good success putting the foil wrapped blades in the cold oven, ramping at max output to 1550 deg. and holding for 5 minutes, then max output ramp to 1975 deg and holding for 5 minutes at that temp. Take out of oven, plate quench between 1" thick aluminum plates, as soon as the pouches are cool enough to handle, open them up and put the blades in the dry ice/denatured alcohol slurry for one hour. Remove from the slurry and let them come to room temperature and then temper the first time at 375 deg for 2 hours, remove and let come to room temperature and temper a second time at 375 for 2 hours. I have ended up with a RC of 60-61.

For those of us with only one oven is it going to be possible to do the double quench well enough to see any meaningful gains?

Thanks for the information and Happy Holidays.
 
Fortunately, Hoss's simplified pre quench solution lets you get back into the oven for the main cycle without having to let that blade sit around and risk the dreaded "ping" from the lower temp "pre-quench" That eliminates a BIG concern for me. I wonder if the oven could get down form 1725 to 1550 while you were finishing up the pre-quench activities? I figure that opening the door at that temp is gone to shed some BTU's pretty quickly,. For me, the problem is eating for it to cool down completely so I can temper as I do not have a second HT oven, kitchen oven, toaster oven, etc, in my shop to do a "snap temper" after cryo or quenching.
drysideshooter said:
So far I have had good success putting the foil wrapped blades in the cold oven, ramping at max output to 1550 deg. and holding for 5 minutes, then max output ramp to 1975 deg and holding for 5 minutes at that temp. Take out of oven, plate quench between 1" thick aluminum plates, as soon as the pouches are cool enough to handle, open them up and put the blades in the dry ice/denatured alcohol slurry for one hour. Remove from the slurry and let them come to room temperature and then temper the first time at 375 deg for 2 hours, remove and let come to room temperature and temper a second time at 375 for 2 hours. I have ended up with a RC of 60-61.

For those of us with only one oven is it going to be possible to do the double quench well enough to see any meaningful gains?

Thanks for the information and Happy Holidays.
Click to expand...
 
Single furnace heat treatment for AEB-L I recommend preheating the oven to 1725, place foil wrapped blade in furnace, soak for 20 min at temp, plate quench. Reset oven temp to 1950-1975, after temp is reached, place blade in furnace and hold for 8-10 min at temp, plate quench.

I do not take my blade out of the foil wrap and I use the same foil for both quenches. My plates are mounted to a wood working vise so I get a good squeeze on the blade. It takes only seconds to cool to room temp. I find the quench to be faster and more uniform if the blade is NOT preground. I grind after HT.

You can do multiple blades within reason, use common sense. I run two ovens.

Hoss
 
The prequench is getting a lot of attention. See attachment, it is studies like these that has us doing a prequench.

Hoss
 

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Sub zero quenching. See attachment, stare at this long enough and it'll start to make sense. This is for high speed steel but shows what happens.

Hoss
 

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So do I read that cryo chart right. On That particular steel the difference between -100 and -310 is less than 2% less retained austenite?

The time bar on the bottom i don't understand, 1 tenth of an hour gets you down to 8% but 10 hours is about 15% ???

I stared at it long enough for everything but the aging time section. Seems backwards.
 
Read the paragraph at the bottom.

The chart shows that the longer you wait to sub zero quench the more RA you get. The colder you take it the less RA also. It does show that there is some benefit at a range of temps.

Stare some more and it should make sense.

Hoss
 
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