There is a lot of information out there about heat treating AEB-L steel for knives. This is what works for me. I have an EvenHeat LB-18 with the Rampmaster controller, and a smaller Evenheat with Rampmaster (primarily used for tempering) that I use for heat treating all my stainless steel. I mention this because you may get different results from different ovens. It is a newer oven and the thermocouple and controller seem to be spot on for proper temperature control.
I got my original information for heat treating AEB-L from Knife Steel Nerds This website is a wealth of great, accurate information on knife steels. I support him with a donation through his site. I highly suggest you do the same. You can donate at Patreon. If you want to see the original article that I got my information from, you can see it here on the Knife Steel Nerds Website
The Formula – AEB-L is a very simple steel to heat treat and gives great results even with simple equipment.
With the Rampmaster program a two segment routine. First segment, ramp as fast as possible(9999) to 1975 degrees F, hold for 5 mins. Set the alarm for 1975 degrees F. This preheats the oven a bit. Second segment ramp as fast as possible to 1950 degrees F if using dry ice, 1925 degrees F if no cryo treatment will be used. I use dry ice so mine is set for 1950 degrees F. Hold for 15 minutes if heat treating 1 knife. If heat treating multiple knives I add 3 mins of time for each knife. (two minutes to plate quench the knife, 1 minute to get the next one out of the oven). My max is 4 knives at a time.
Once the 1975 degree temp has been reached, I wait until just before the timer expires then open the door and insert the knives. The temperature will drop a bit below 1950, so this prevents the timer on the second segment from starting while I am loading the knives in the oven. Once the temp reaches 1950 the timer will start the 15 minute countdown.
Out of the oven the knives are plate quenched using two 4″ x 18″ x 1″ aluminum plates and hand pressure. I keep a spare set of plates in case mine get too warm. I can put them in the dry ice to cool down, and keep heat treating if I need to. From there they room cool, then into the dry ice until the next day.
The knives are then checked for hardness using a Rockwell hardness tester and/or hardness files. This formula seems to consistently produce knives as quenched at HRC 63+.
From there I temper depending on the type of knife I am making. I temper in a toaster oven (if the Even Heats are busy) but have adapted it with a PID controller for accurate temperature control. For my Basic Series Chefs Knives I temper at 365 degrees F 2 x 2 hrs. The result is right about 59-60HRC. I think this is perfect for the home chef and the beginning professional chef. Relatively easy to sharpen, a bit of toughness to take a bit of abuse. My Professional Series Chefs Knives are tempered at 325 degrees F to get the maximum hardness I can. These knives usually measure at 61-62HRC. Pretty sure this is about as hard as AEB-L is going to get without Liquid Nitrogen. Many of my Professional Series Knives are made with CPM-154 or CPMS35VN. Although these steels may be more abrasion resistant and have better edge holding, the AEB-L gets every bit as hard and performs very well under normal use.
I adjust the tempering to 425 degrees F for boning knives, steak knives, and heavy chefs knives, preferring to see something in the 57- 58HRC range. That’s pretty much the scoop! Can’t give enough thanks to Knife Steel Nerds and the New Jersey Steel Baron for helping me find the right formula for my knives!