Ramping Oven from the Preheat to the Soak Temp

CDHumiston

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When I am doing a preheat for 15 minutes at 1500° and then ramping to 1925° I assume I leave the blades in the oven even though this rise in temp may take upwards of 30 minutes.

Is this correct?
 
When I am doing a preheat for 15 minutes at 1500° and then ramping to 1925° I assume I leave the blades in the oven even though this rise in temp may take upwards of 30 minutes.

Is this correct?
Yes , but as far as I know nobody is doing that with knifes . Large thick parts with a complicated shape , yes .
 
After reading what I could find on it, I settled on letting my oven come up to temp, stabilize for a bit until it is keeping tight temperature and the fire bricks have warmed up. Then I put in the knife, let it come back to temp, and start the time.

Based on these forums it seems that people do it both ways.

Some years ago someone, I think it was Marchand, posted about ovens overshooting temperature during a ramp. I remember it being good reading if you can find it.
 
I
Yes , but as far as I know nobody is doing that with knifes . Large thick parts with a complicated shape , yes .
I see, it's so hard with all the different information out there.

The blades seem to have come out fine. The hardness is right around 61HRC for them all. That's a mix of AEB-L, 440C and D2.

The temps were different for them all as were the preheat and soak times.

I may snap one in half to take a look at the grain structure...
 
I

I see, it's so hard with all the different information out there.

The blades seem to have come out fine. The hardness is right around 61HRC for them all. That's a mix of AEB-L, 440C and D2.

The temps were different for them all as were the preheat and soak times.

I may snap one in half to take a look at the grain structure...
I don t think you need to snap one ,you don t do anything wrong with your HT protocol .
 
  1. Put in 1725 degree oven - Wait 20 minutes
  2. Plate quench
  3. Wait 30 minutes
  4. Put in 1950 degree oven
  5. Let oven ramp to 1990 degrees (takes 5 minutes)
  6. Wait 20 minutes
  7. Plate quench
  8. 59hrc
  9. Liquid Nitrogen - Wait 2 hrs
  10. 61hrc
  11. 350 oven - wait 2 minutes
  12. 63hrc
A recommended heat treat for AEB-L that I've used with successs.
 
I missed the first plate quench in your steps, and I don't have liquid nitrogen, so I didn't cryo.

My blades are at 62HRC after the second tempering cycle.
 
Is that 2 minutes a typo? Perhaps 2 hours?
I can't speak for L LCoop , but I do that 2 minute thing. AEB-L comes out of the LN about 2 points lower than I want. I stumbled on the weirdness of heating the blade just a bit after the LN to get full hardness. I asked Larrin about it and he confirmed that it happens (sorry I can't remember why). I haven't noticed that on S30V, Elmax, CM154 ... just AEB-L. So it's part of my cycle now. I did find that I only need 2 minutes at 200.
 
I don't fully understand, do you mean you only temper for 2 minutes after LN? No more tempering at all? If so, you're using the blade almost "as quenched" with only 2 minutes of temper? I've read that 30 minutes is actually sufficient time to convert RA, but 2 minutes is barely time for the blade to warm up at all - "IF" I'm understanding what you're saying.
 
I don't fully understand, do you mean you only temper for 2 minutes after LN? No more tempering at all? If so, you're using the blade almost "as quenched" with only 2 minutes of temper? I've read that 30 minutes is actually sufficient time to convert RA, but 2 minutes is barely time for the blade to warm up at all - "IF" I'm understanding what you're saying.
Oh No! It's not a replacement for tempering. It's just warming up the blade after LN to complete the hardness.

Here's the old thread on the topic. https://bladeforums.com/threads/strange-cryo-on-aeb-l-anomaly.1646288/#post-18829374


Sorry CDHumiston CDHumiston if this is hyjacking your question! I've often wondered the same thing as you, because my oven is pretty slow reaching temp.
 
OK, now I understand. The 2 minutes at 350F is mostly to get blade up to room temp type of thing. You're right, AEB-L right off the quench plates isn't going to test for Rc at all, nor fresh out of dewar. Either place it's got to sit a few minutes to "stabilize" (or something). Fresh off the quench plates an AEB-L blade will bend like wet noodle.
 
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