Kitchen knife hardness

JTknives

JTknives

Blade Heat Treating www.jarodtodd.com
Knifemaker / Craftsman / Service Provider
Joined
Jun 11, 2006
Messages
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I am wondering what your thoughts are concerning blade hardness for kitchen knives. It seams like I’m seeing a trend to push the hardness to the max lately. This seams especially true with aebl 64-65 range. The only blades that have snapped on me are thin aebl in this very high hardness range. Aebl in the 61-63 range seam quite stable but once pushed over that 63rc threshold thy seam twitchy. The high hardness requests seem to have really increased after the Steel Nerds article on AEBL.

My thought is if you need to push it that hard you might want to look at another alloy to get what your chasing. I feel this is just asking for a snapped tang or a chip out of the edge which could end up in food.

So being that I’m not a kitchen knife expert I’m wondering what your thoughts are on this.
 
Purely from a user's perspective, but I tend not to trust a knife over 63rc. I have never handled a knife over 63rc that didn't turn out to be brittle, leaving me with a chipped edge (or worse, two halves of a blade). Especially in thin AEBL, I find 61-63 to be the sweet spot.

I am glad that my experience matches up with yours, cus if I were to ask someone about heat treating it would be you.
 
I’m in agreement that AEBL is perfectly sufficient at 61/62 rc. I’m not seeing AEBL as desirable to go harder than this

z wear I would say is different and suitable at 63/64 for kitchen knives
 
I was considering going harder on AEB-l, but I haven’t tested it at that toughness.

Harbeer is right about z-wear. Rc64 is fine in the kitchen. I’ve done Rc65 without problems so far, but time will tell.
 
scarysamcary said:
Purely from a user's perspective, but I tend not to trust a knife over 63rc. I have never handled a knife over 63rc that didn't turn out to be brittle, leaving me with a chipped edge (or worse, two halves of a blade). Especially in thin AEBL, I find 61-63 to be the sweet spot.

I am glad that my experience matches up with yours, cus if I were to ask someone about heat treating it would be you.
Click to expand...

A few steels like z-wear, M4, V4e and such are quite stable at Rc64/65. They are as tough at that hardness as O1 or 1095 at Rc60.
 
AEBL I like at 62-63HRC, and agree that if you're trying to get more from it, try a different alloy. Z Wear is relatively new for me, but like Warren said above, 64HRC works very well.
The low alloy stuff like 1095, W2, Super Blue, etc, I like them at 65HRC.
 
I have made quite a few thin kitchen knives out of power hack saw blades, M2 at 64-65rc, always rave reviews with zero issues.
 
Interesting, seems my heat treatment must have a different threshold.

64-65rc is Killer.

I recommend a LN cryo.





JTknives said:
I am wondering what your thoughts are concerning blade hardness for kitchen knives. It seams like I’m seeing a trend to push the hardness to the max lately. This seams especially true with aebl 64-65 range. The only blades that have snapped on me are thin aebl in this very high hardness range. Aebl in the 61-63 range seam quite stable but once pushed over that 63rc threshold thy seam twitchy. The high hardness requests seem to have really increased after the Steel Nerds article on AEBL.

My thought is if you need to push it that hard you might want to look at another alloy to get what your chasing. I feel this is just asking for a snapped tang or a chip out of the edge which could end up in food.

So being that I’m not a kitchen knife expert I’m wondering what your thoughts are on this.
Click to expand...
 
I had to take back one of my first knives. It was 58 HRC I didn't have a tester when I made it. 60-61 isn't great in my opinion. Did a bunch at 62 and they were decent. Have a paring knife at 63 and it's fantastic and holds an edge must better. My wife has been abusing it on plates to see how it hold up and no issues.

If I ever get my latest steel order I'm going to run a few at 64 to see how they perform. Given the toughness of AEB-L I think a 64 HRC slicer would be great but I won't send one out until I abuse it for a bit. I think it'll still be less prone to chipping than something like a VG10.
 
my concern with aebl at extreme high hardness would be pretty specific to full size Jaanese style chef knives. I.E. big blades with narrow necks, there was a venodr who had a bunch of cleavers made up in high hardness aebl and they snapped at the necks if they were dropped far too easily. It seems like if you are going for extreme high hardness it would be wise to use differentially hardened steel or san mai steel. a catastrohic failure is just no good, and with a fully hardened mono steel at high hardness just seems like you are asking for it. Blades that are used every day will eventually get droped or used to cut something it should not.
 
timos- said:
my concern with aebl at extreme high hardness would be pretty specific to full size Jaanese style chef knives. I.E. big blades with narrow necks, there was a venodr who had a bunch of cleavers made up in high hardness aebl and they snapped at the necks if they were dropped far too easily. It seems like if you are going for extreme high hardness it would be wise to use differentially hardened steel or san mai steel. a catastrohic failure is just no good, and with a fully hardened mono steel at high hardness just seems like you are asking for it. Blades that are used every day will eventually get droped or used to cut something it should not.
Click to expand...
A vendor selling your knives?
 
timos- said:
my concern with aebl at extreme high hardness would be pretty specific to full size Jaanese style chef knives. I.E. big blades with narrow necks, there was a venodr who had a bunch of cleavers made up in high hardness aebl and they snapped at the necks if they were dropped far too easily. It seems like if you are going for extreme high hardness it would be wise to use differentially hardened steel or san mai steel. a catastrohic failure is just no good, and with a fully hardened mono steel at high hardness just seems like you are asking for it. Blades that are used every day will eventually get droped or used to cut something it should not.
Click to expand...
My guess is they were cut out in the transverse direction, it wouldn’t be a problem if they were cut out in the longitudinal direction.

Hoss
 
The steel is going to vary a little bit in terms of its peak potential hardness based on the individual heat (especially carbon and chromium). 65 Rc is not consistently possible to achieve. I recommend using 1975F along with a fast quench (plate or oil), cryo, and 300F tempers and see where the hardness ends up. It should be in the ballpark of 64 Rc.
 
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