AEB-L fail

colu41

colu41

Joined
Dec 24, 2014
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1,598
Tried to HT my first 3 AEB-L blades today. Here was my procedure.
Preheated blades to 1560° soaked for 5 minutes.
Ramped to 1940° soaked for 15 minutes, plate quenched immediately.
After taking them out of foil, I noticed they didn't seem to harden a bit. I don't have a hardness tester but considering I took one and bent it into a U, I'm guessing it's not hardened. What did I do wrong?

Btw. Blades were wrapped in foil. (2) were .07 stock and one was 1/8"
 
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I've read of a few different temps to use. 1940°, 1975°, & 1995°... Are one of these critical? I did everything according to procedure.
One of these blades I need to finish for this weekend as I'm donating it for benefit auction. And just would really like some tips on anything I may have done or should watch for?
I might just try the higher temp procedure and see what happens.
 
Did you test the edge with a file?

How did you measure your austenitizing temperature?

Bending a knife after quench is not a good test. MS Tom Ferry quenched a knife made from 1080 and then placed the knife in a vice and bent it 90°. Half an hour later he went back to the blade in the vice and pulled on it. The blade snapped like glass.

Chuck
 
Alpha Knife Supply said:
Did you test the edge with a file?

How did you measure your austenitizing temperature?

Bending a knife after quench is not a good test. MS Tom Ferry quenched a knife made from 1080 and then placed the knife in a vice and bent it 90°. Half an hour later he went back to the blade in the vice and pulled on it. The blade snapped like glass.

Chuck
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That's interesting. Because the same thing happened to me least night. I was going to delete this thread because of it. I snapped one of my fillets in half bending it. Weirdest thing ever.
 
I did sub zero quench it after the initial quench. So I don't know if that gave it a little more hardness or if it was some sort of delay thing like you are talking about.
 
My guess is that you had not reached the Mf yet. Complex steels take much longer and need lower temperatures to reach MF. You had lots of austenite after taking out of the quench plates. A day later, it was harder and broke. Doing a sub-zero treatment as the finish to the quench assures the steel is at Mf and lowers RA.

Just to be clear on another thing, bending has no bearing on hardness. A .07" blade will bend the sane amount hard or soft. The difference in hardness determines whether it stays bent , returns to straight, or breaks.
 
In my limited experience I have found it tough to tell hardness without a tester. If you've done thousands of blades then its probably easier. Find a local machine shop that makes tooling, or a local maker with one, and they will probably test them for you. I feel its important to be able to tell my customer what the hardness is exactly and not what it should be.
 
I'm going to have to invest in a tester soon.
Anyways thanks guys.
And Stacy, that's the weird thing. Right after quench they just didnt feel right to me. I took one of the thin fillets, bent it and it stayed bent. That was my first worry. So I said to hell with it and threw them in my dry ice and alcohol since it was ready. Took them out a few hours later, and this time I tested blade with a piece of the stock by attempting to drill. The "hardened" piece barely left a mark when I tried drilling. Then I bent it again and came back beautifully. Gave it a little more pressure and snapped it. So I'm guessing that just maybe they came out decently hard. Just took the sub zero quench to kick it in maybe.
I'll still have them checked today though.
 
Just curious. Is it to late to temper a day later? I didn't temper last night as it was getting late, and I figured I might have to re-heat anyways.
 
Your description sound like the blade was not at Mf at first and was later on. You can temper after a day. It won't matter much.

During the quenching zone between Ar1 and Mf the blade can be bent easily. Between Ar1 and Ms it is all austenite and can be almost rubbery.
 
Stacy E. Apelt - Bladesmith said:
Your description sound like the blade was not at Mf at first and was later on. You can temper after a day. It won't matter much.

During the quenching zone between Ar1 and Mf the blade can be bent easily. Between Ar1 and Ms it is all austenite and can be almost rubbery.
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Thanks again Stacy. This stuff is fascinating to me. Lol. I've just never experienced something like that out of the 40+ blades I've done. But then again this is the thinnest stock I've ever used also so maybe I just never noticed it before. I'm going to temper today and then get them tested.
 
The one that snapped I would take a piece of that when you check hardness to collect data on the before tempering hardness so you have an idea of the after quench pre cryo/temper hardness.
 
Busto said:
The one that snapped I would take a piece of that when you check hardness to collect data on the before tempering hardness so you have an idea of the after quench pre cryo/temper hardness.
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I may do that.

A little off topic but, I went on that HGR Industrial, and they have an Ames portable RC Tester on there for $99. Is that legit? Theres no other info on it, like if it needs parts or anything like that.
 
Actually that would be a good buy IF the diamond indenter is intact without seeing model number....Model 1's used are generally around 300-600 with a good diamond. Replacement diamonds are about $300 but they are a good tool for the money also check the ebay for a comparable model.
 
I'm on my 3rd one I love this stuff. I put the blade in a cold oven, take it to 1995 soak 10 min, plate quench while shooting compressed air around the edges to cool faster. Remove blade from package sub zero with Dryice and alcohol. Temper 1hr 400 X2
 
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