Bad steel???

scott kozub

scott kozub

Joined
Jan 1, 2018
Messages
861
I've have recently had a batch of failures all from the same plate of AEBL Hardened to 63 hrc. I've had 3 knives where I found hairline cracks on the edge while hand sanding, a boning knife that snapped when checking the flex while grinding and hidden tang knife where the tang snapped during testing. As noted, all knives were from the same plate from a reputable dealer.

1975 heat treat and tempered several times to achieve 63 hrc. I've never run into this. Could it possibly something with the steel? All were cryo'd in LN. Edges were all about .001 to .002" TBE.

The knife that snapped had no noticble grain growth.
 
In addition to Tom's questions, what are your exact HT steps? How are you quenching - aluminum plates? How warm are the blades when you put in LN? I usually put my blades from quench plates to freezer for a few minutes before LN.
 
I ever had several D2 blades cracked from putting in dry ice + acetone too sudden like dunk into in directly from 150F warm. The rough grind left around the edge also plays big factor of quench cracking from my experience.
 
These were heat treated at 1975 for about 9 minutes. Plate quenched with compressed air between 2 1" plates in a wood workers vice. Once they could be handled the foil was removed. I dunked them in water and dried before going into the LN. All grinding was done post heat treat. The knives were cut from 11x23" sheets of 0.09" AEBL from alpha. Any straightening required was done after temper via a peening hammer which is likely the main cause. Hardness was confirmed with an AMES tester.

I'm also wondering if I cracked the edges while hand sanding. I keep the edge just hanging off the edge of the 2x4 support and maybe it was flexed too much.

Could be numerous causes. Just weird that this plate seems to be cursed.
 
Sounds like you did everything right - I can't imagine cracking the edges while hand sanding.
 
If you got your steel from Alpha then I think you can be confident that it was AEB-L steel. The reason I asked is I sent some AEB-L off to a heat treater and it turned out NOT to be AEB-L steel. This steel did NOT come from Alpha.
I have complete trust in the steel Alpha sells.
 
We're the knives cut transverse to the rolling direction of the plate??
 
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