General HT ramp rates

K

Kulshan

Joined
Dec 16, 2019
Messages
2
Hey all,
Total knife noob and long time lurker here based in Seattle and finally decided I had a question worth posting. I'm generally pretty handy and have most of the right tools for this hobby so I've decided to try my hand at a pair of chef's blades in AEB-L (for Christmas gifts no less! We'll see about that timeline...).
I got the blades profiled and handle holes drilled out and started my heat treat using the following recipe:
SS foil wrap.
1750F for 10min, plate quench.
1975F for 15 min soak at temp, plate quench.
Remove foil.
Dry ice/isopropyl slurry for about 2 hours.
Snap temper at 320F for 30min (ran out of day to finish temper)
Currently working on the final tempers now, 2x 350F for 2 hours each. This is more or less what I've seen around for AEB-L, but i noticed one thing with many of these HT recipes that's missing and that's ramp rates, i.e. how quickly the oven can get from one temperature to a (usually) higher temperature.
I only notice this because I have a fairly small HT oven with a small 1600W element (limited to 120V). It seemed to me that when I opened the oven to put the blades in, the temperature would drop almost 300F and take a significant amount of time to get back up to 1975F (15+ minutes). Add this to a 15 minute soak once to temp and it would seem to me that these blades have been at high heat for too long? I may be overthinking this since the blades are not even done with temper yet, but it got me to thinking, what is a normal ramp rate for HT ovens and how can one compensate for slow ramp rates if the oven is not capable for fast enough ramps?
Sorry if this was a bit long winded, but is there any way to save these blades if I have over soaked them at high temp? Thanks to all for any help you might have.
 
Kulshan said:
Hey all,
Total knife noob and long time lurker here based in Seattle and finally decided I had a question worth posting. I'm generally pretty handy and have most of the right tools for this hobby so I've decided to try my hand at a pair of chef's blades in AEB-L (for Christmas gifts no less! We'll see about that timeline...).
I got the blades profiled and handle holes drilled out and started my heat treat using the following recipe:
SS foil wrap.
1750F for 10min, plate quench.
1975F for 15 min soak at temp, plate quench.
Remove foil.
Dry ice/isopropyl slurry for about 2 hours.
Snap temper at 320F for 30min (ran out of day to finish temper)
Currently working on the final tempers now, 2x 350F for 2 hours each. This is more or less what I've seen around for AEB-L, but i noticed one thing with many of these HT recipes that's missing and that's ramp rates, i.e. how quickly the oven can get from one temperature to a (usually) higher temperature.
I only notice this because I have a fairly small HT oven with a small 1600W element (limited to 120V). It seemed to me that when I opened the oven to put the blades in, the temperature would drop almost 300F and take a significant amount of time to get back up to 1975F (15+ minutes). Add this to a 15 minute soak once to temp and it would seem to me that these blades have been at high heat for too long? I may be overthinking this since the blades are not even done with temper yet, but it got me to thinking, what is a normal ramp rate for HT ovens and how can one compensate for slow ramp rates if the oven is not capable for fast enough ramps?
Sorry if this was a bit long winded, but is there any way to save these blades if I have over soaked them at high temp? Thanks to all for any help you might have.
Click to expand...
Nah, you're fine, that is not oversoaking.
 
Read this for the total information of AEB-L and ite HT:
https://knifesteelnerds.com/2019/03/04/all-about-aeb-l/

Your parameters are good, but I would drop all tempering to 300F. AEB-L is a low tempering steel.

I use plain old denatured alcohol (methanol/ethanol mix) from the hardware store ( $15 a gallon at HD) in my dry ice slurry.
 
Last edited:
Thank you both for your replies. Glad to hear that they aren't over soaked. They will both skate a file, so that's good. Curious what actual HRC I ended up with but I have no way to test at this time.

Stacy, that link doesn't appear to be right. It sounds like the actual would be an article I would be interested to read.

I am still curious though, what sort of ramp rates would one expect to see on a more powerful oven? and what would be considered 'too slow'?
 
You could program two segments, first above the austenitizing temperature and the second at the austenitizing temp. You’ll need to figure out how much above, dependending on your personal oven and your speed inserting the blade.

Once temp for first segment is reached, insert the blade and skip to the next segment.

When you open the door, the temp should drop closer and a bit below the second segment target temp and therefore you won’t have to wait that long.

Now, you still have to account for how long it will take the blade to reach soaking temp.

Hope this helps,
Constantin
 
I missed answering the ramp rate question. I ramp at 9999 up to the first target and then at 5000 to the final target when doing two consecutive steps (pre-soak, etc.)

In your case, with the pre-quench, just ramp at 9999 for both steps. Insert the blade when the oven has stabilized.
 
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