AEB-L hardness in the kitchen

Greenberg Woods

Greenberg Woods

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Dec 27, 2013
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Hey again folks. I have made 16-17 AEB-L chef knives over the past months and they are finally being finished up and ready to be sent off for heat treatment. My question was, what hardness would you suggest on AEB-L destined for the kitchen? I have seen a range from 60 HRC all the way to 64. I havent really handled much hardened AEB and was wondering what you guys would suggest. The knives are a mix of 8 inch chefs and 5-6.5 inch long santokus.
 
Although I am probably wrong, I'm from the school of more is better. I've heat treated/tempered mine to 62Rc. No kitchen knives yet though.
 
hellspawn415 said:
I was thinking of taking the larger western blades to 61 and the santokus to 62
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The way it seems to me (definitely not an expert), for pure slicers (like a santoku) you can go higher, for knives that will turn or torque the edge (like for rock chopping or a parer) should be slightly lower so less likely to chip. That is how I plan on doing mine when I get back to the states and make some kitchen knives I've been thinking about
 
it depends a lot on how much hardness they can get "as quenched"; if the ht guys could get maximum hardness the microstructure is probably fine and you could use the blades tempered down to 63-64 hrc. Of course such hardness will work in the hand of a good chef.
20-22° edge is the way to go.
 
There has been some discussion about how and WHEN you do the cold treatment and what impact that has on final as-quenched hardness and as a result, what you can reasonably expect for final tempered hardness. Do any of you guys go straight from the quench to a quick cold treatment before going into the first temper?
 
We have an AEB-L slicer made by Devin Thomas that is HRC 62. The thickness at the spine is .080" and there is a tiny secondary bevel. We've used the knife for a few years and we cannot get it to chip. One of the ways I abused it was deburring aluminum dies in the shop. My experience is when AEB-L is properly heat treated, HRC 62 works very well.

Chuck
 
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jdm61 said:
There has been some discussion about how and WHEN you do the cold treatment and what impact that has on final as-quenched hardness and as a result, what you can reasonably expect for final tempered hardness. Do any of you guys go straight from the quench to a quick cold treatment before going into the first temper?
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I go from plate quench to dry ice/denatured alcohol as soon as it's cool enough to handle (roughly room temp). I leave them in the sub zero for about a half hour and then hang them on a little rack I made till they reach room temperature, then they go straight into the preheated oven for the two-two hour tempers.
 
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That is pretty much what I do, also.


Remember, real world hardening and forming martensite is best viewed on a CCT...a CONTINUOUS Cooling Transformation graph/chart. Accent the word continuous if you want the max hardness. The drop from 1950F to -300F should be more or less a continuous drop. There may be short plateaus, but there should be no long rests if martensite is what you want. Doing it with snap tempers or overnight waits won't ruin a blade, but there is a slight gain to doing it as a continuous drop.

Because of the lack of larger carbides, AEB-L has a very fine grain edge that holds up well. The ability to make a keener edge is also increased. This combo makes it a great choice for kitchen slicers.
 
Do i need to finish the blades before I send them for heat treatment? they are at a 60 grit finish right now. To reduce cracking/ warping should I take them finer?
 
Yes...for two reasons.
Large and deep scratches are not good for HT.
But the big reason is they will be many times as hard to remove after HT. I take kitchen blades to at least 400 grit pre-HT, and one of my friends polishes them before HT.
 
No doubt the professional heat treaters can process a very thin finished blade, but what works for me is pretty much finishing blades that are 1/8 or thicker, but grinding bevels after HT on thinner ones...I just get too much warping and cupping on those.
Maybe someday I'll crack the secret stability code!
 
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