Kiln Elements Burnt out SOS.

jwood

Member
So I was heat treating an AEB-L santoku I’m making for a customer, 20 minutes at 1560°F and 8 out of the 15 minutes at 1940°F. I left the room for a bit and came back and the readout of the kiln was at 1320°F my elements burned out and I said lots of four letter words.
I have new elements on order but that’ll put me behind at least 3-4 days.

Is there anyone in Georgia maybe around Atlanta that would be willing to let me heat treat one blade, I’d be willing to pay, and I have my own stainless wrap. I’m in a time crunch for this blade and any help would be greatly appreciated.
 

Kev

Well-Known Member
You may want to do a hardness check, because I’d bet it’s there. Maybe not 110%, but I’d bet it’s fine. I’m not a metallurgist by any stretch but I’ve done a bunch of AEB-L and unless it’s really thick I only soak for 10 minutes.
 

KenH

Well-Known Member
Jwood, the last post last night clicked for me - you got 8 minutes at 1940F? Unless it's a very thick blade that's more than enough time for full hardening - 8 minutes is what DevinT recommends for AEB-L (see below). Take a look at Sandvik's numbers for 13C26 which is the same as AEB-L. Also, since it's already been hardened it will require annealing before re-HT'ing again. Annealing requires a soak for 12 hrs or so per Devin T (Hoss)"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.

(DevinT's HT - less than 1/8" thick)

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, 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 62-63 Rc range to 61-62 Rc range. Moving to 400F would expect to drop another point.
 
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jwood

Member
My concern is that the temperature was dropping before I realized to take it out to quench. It does seems slightly harder it’ll skate my file when I try to draw file my flat grind but the file will bite into the edge. I would just hate to give a costumer a blade with a questionable heat treat.

And the blade is 1/8”
 

KenH

Well-Known Member
My concern is that the temperature was dropping before I realized to take it out to quench
That makes sense, maybe it only had a couple of minutes at 1940°F - if a file will bite into blade than I'd expect it to be on the soft side. With AEB-L I'd like something around 60Rc at least. I can check Rc if you desire to ship to me. If Rc is low I'd need to put in oven at 1350°F for 12 hours, allow to cool then do the normal HT next day.
 
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