Broken WIP kitchen knives. Who is to blame?

Joshua Fisher said:
A friend I work with personally ordered “aeb-l” from aks some time last year or the year before that was not hardening correctly and cracking without him even straightening and I believe we figured out it may have been A2 I think it was the same 1/16” thickness, they eventually sent him a refund for the steel, I’d suggest reaching out and see if they can track that bar just to confirm it is aebl and rule that out of the equation. I plate quench and straighten 1/16” stock quite regularly and haven’t had any issues with cracking either aebl or nitro-v JTknives JTknives I’m not sure if you already do this but on identical profiles I clamp them as a stack between two straight pieces of angle iron and leave them clamped for cryo and both temper cycles before removing the clamps and that has drastically reduced warping especially on thinner stock.
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I purchased it December of 2024 so that time frame may coincide. I will reach out to AKS to see what they say.
I do notice it rusts a little if I set it down wet after a grinding stage but that could be dust from grinding other steels getting stuck in the blade so not conclusive there as to whether it some non-stainless steel marked incorrectly. I could try blueing compound but I had limited success using that as a test before on other things.
 
Dunk it in ferric chloride for 20-30 seconds if you have some. I had a couple blades I thought were AEBL and treated that way, but were 1095. Acid test showed carbon steel right away!
 
Thanks Josh. I recalled that situation but didn't want to mention the incident without further discussion. That is why my first suggestion on why it cracked and broke was the steel may be wrong. I agree, contact AKS.
 
Joshua Fisher said:
A friend I work with personally ordered “aeb-l” from aks some time last year or the year before that was not hardening correctly and cracking without him even straightening and I believe we figured out it may have been A2 I think it was the same 1/16” thickness, they eventually sent him a refund for the steel, I’d suggest reaching out and see if they can track that bar just to confirm it is aebl and rule that out of the equation. I plate quench and straighten 1/16” stock quite regularly and haven’t had any issues with cracking either aebl or nitro-v JTknives JTknives I’m not sure if you already do this but on identical profiles I clamp them as a stack between two straight pieces of angle iron and leave them clamped for cryo and both temper cycles before removing the clamps and that has drastically reduced warping especially on thinner stock.
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Yeah we clamp them to steel when we have room. When doing 20 to 30 blades at a time it gets real hard as that’s a ton of clamps and freezer space for cryo.
 
Stacy E. Apelt - Bladesmith said:
Thanks Josh. I recalled that situation but didn't want to mention the incident without further discussion. That is why my first suggestion on why it cracked and broke was the steel may be wrong. I agree, contact AKS.
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I’m removing this comment as I just talked to AKS and this is not what happened. As I have said here and to all my customers “AKS is the best from my experience”.
 
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JTknives said:
Could that be what’s causing the weird pattern I got in 2 separate orders? If it is A2 then it would be massively over heated if treated as AEBL.
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What are your thoughts on the video that Jesse posted of a thin AEB-L knife with a similar requested harness and flexes almost 90 degrees? I assumed a kitchen knife wouldn't withstand that level of abuse but I never dare test my knives like that.
 
I've done it for fun. It is sphincter clenching to do, but seeing it come back is amazing. The finish needs to be perfect and at least 800 grit. Go slow and a knife that thin will bend easily with force. In use you will rarely notice any flex. My flounder/fluke fillet knives will do that demo easily, but they are probably .040" at the thick part.
 
I just talked to eyeeatingfish. This situation is odd. We rarely hear of anyone having cracking issues with AEB-L, especially considering how tough the steel is.

In response to Josh's question about the steel being mislabeled, this steel is definitely AEB-L. We have strict procedures that are followed in the shop to ensure steel is labeled properly. If this steel had been something like A2, it would acted much differently during heat treat.

I also know the batch of steel this came from. This AEB-L had been set aside out in the shop because it got some gouges on the surface and couldn't be sold with our typical AEB-L due to it's surface finish. We put it on clearance as "blemished" with a significant discount knowing that it would require more work to get out the scratches.

I suspect stress risers may have been the problem, especially considering this steel had surface gouges and scratches. If the gouges were not removed prior to heat treating, they potentially could have caused additional stress that resulted in cracks.

- Jessica Walker
 
Alpha Knife Supply said:
I just talked to eyeeatingfish. This situation is odd. We rarely hear of anyone having cracking issues with AEB-L, especially considering how tough the steel is.

In response to Josh's question about the steel being mislabeled, this steel is definitely AEB-L. We have strict procedures that are followed in the shop to ensure steel is labeled properly. If this steel had been something like A2, it would acted much differently during heat treat.

I also know the batch of steel this came from. This AEB-L had been set aside out in the shop because it got some gouges on the surface and couldn't be sold with our typical AEB-L due to it's surface finish. We put it on clearance as "blemished" with a significant discount knowing that it would require more work to get out the scratches.

I suspect stress risers may have been the problem, especially considering this steel had surface gouges and scratches. If the gouges were not removed prior to heat treating, they potentially could have caused additional stress that resulted in cracks.

- Jessica Walker
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Good to hear, I know there was an issue with one bar/sheet in the past that my friend had and it was taken care of and it definitely had an off heat treating response. Figured with this looking like a similar time period it was worth checking.
 
Could this be something due to the initial condition? I didn't see a reference to annealing or normalisation

eyeeatingfish said:
I assumed a kitchen knife wouldn't withstand that level of abuse but I never dare test my knives like that.
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Depends on the geometry. Remember kitchen knife covers a lot of design space
I've made a couple that might do it, haven't tried, but personally i prefer less flexible knives so don't normally do that
 
Alex Topfer said:
Could this be something due to the initial condition? I didn't see a reference to annealing or normalisation
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I have some leftover pieces in my recycle bin from that bar. I will try a few tests on it including an acid dip to see if it behaves like stainless and bend it to see if it behaves like annealed steel. I could try other things if there are any suggestions.
 
Jessica, Thanks for posting that info. That certainly seems to remove any doubt about it being AEB-L. As you suggested, it is now most likely a strress riser issue. Maybe from the gouges, maybe from the grinding, maybe from some other source we haven't considered. At this point we may never know.

I will point out to anyone reading this thread that Alpha Knife Supply , its founder Chuck Bybee (RIP), Jessica, and the crew, all have built a great resource business for knifemakers. They are a quality supplier and good people. Buying from AKS is a reliable and fast process.
 
Joshua Fisher said:
Good to hear, I know there was an issue with one bar/sheet in the past that my friend had and it was taken care of and it definitely had an off heat treating response. Figured with this looking like a similar time period it was worth checking.
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Josh, the "issue" you are referring to was not the same timeframe. The last time you and I talked about it, you brought it up in Nov of 2023 and said your friend had it happen recently. I still have questions regarding that situation, but I don't think it's worthwhile playing he said/she said.

The AEB-L eyeeatingfish purchased was in December of 2024.

Stacy E. Apelt - Bladesmith said:
Jessica, Thanks for posting that info. That certainly seems to remove any doubt about it being AEB-L. As you suggested, it is now most likely a strress riser issue. Maybe from the gouges, maybe from the grinding, maybe from some other source we haven't considered. At this point we may never know.

I will point out to anyone reading this thread that Alpha Knife Supply , its founder Chuck Bybee (RIP), Jessica, and the crew, all have built a great resource business for knifemakers. They are a quality supplier and good people. Buying from AKS is a reliable and fast process.
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Thank you for your comments Stacy, I really appreciate it.

- Jessica Walker
 
Alpha Knife Supply said:
Josh, the "issue" you are referring to was not the same timeframe. The last time you and I talked about it, you brought it up in Nov of 2023 and said your friend had it happen recently. I still have questions regarding that situation, but I don't think it's worthwhile playing he said/she said.

The AEB-L eyeeatingfish purchased was in December of 2024.



Thank you for your comments Stacy, I really appreciate it.

- Jessica Walker
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Sorry Jessica I wasn’t intending to create an issue and you all took care of the steel which in my mind resolved that problem. I couldn’t rember the exact date but knew it was somewhat recent and some of the cracking reminded me of that situation so figured would be worth double checking. Again didn’t mean for it to be a negative conversation but just ruling out that it wasn’t from a similar batch of steel which it looks like that’s not the case. Hope you all are doing well
 
A couple small updates from my testing of the spare pieces from the bars.
1. The file did bite into them so they were soft.
2. I was able to bend a 3" piece into a U shape as well as bend one piece back and forth a dozen times with no snapping.
3. The blueing solution did darken the steel though I don't know that this proves anything.
4. A 5 minute soak in ferric chloride took the sheen off completely leaving a very matte light gray finish. That would seem to indicate it is stainless.

I also looked closely at more broken pieces of the heat treated blades. The center looked pretty uniformly grey however I noticed that the outside 0.5mm or so had a little sparkle like a more crystalline texture. It was on both side of the break, like a little ring around the outside. I don't know enough about the science of heat treating to interpret this, maybe a break will always have a different texture right at the surface? It sure didn't like to bend though.
 
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