uh oh...another AEB-L (Nitro V) question

E

elementfe

Joined
May 3, 2008
Messages
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Well, I tried the ATP 641 from Jantz...seemed good, but when I went to grind them, not only was the dark residue incredibly hard, the steel underneath is eating belts like nothing I've seen.
As usual, I think I'm missing something obvious- what could it be?
Has anyone else had this experience? Suggestions?
I have a lot of belts, and i don't know if I have enough to get this batch ground...

Austenized @ 1950 oil quench then dry ice as soon as I could handle it without gloves. Tempered at 300, tried a couple at 325, no improvement in grinding.
One odd thing, the steel under the black coating was pitted somewhat- I assume a second coat would have helped that. I used one heavy coat, then touchup
 
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You might want to consider investing in stainless foil for your air hardening blades. The initial outlay of money might seem high but you're not going to have to battle the decarb/crust that eats belts, time and money quickly if you do.
AEB-L should be one of the easier steels to grind post heat treat when foil is used.
 
elementfe said:
Well, I tried the ATP 641 from Jantz...seemed good, but when I went to grind them, not only was the dark residue incredibly hard, the steel underneath is eating belts like nothing I've seen.
As usual, I think I'm missing something obvious- what could it be?
Has anyone else had this experience? Suggestions?
I have a lot of belts, and i don't know if I have enough to get this batch ground...

Austenized @ 1950 oil quench then dry ice as soon as I could handle it without gloves. Tempered at 300, tried a couple at 325, no improvement in grinding.
One odd thing, the steel under the black coating was pitted somewhat- I assume a second coat would have helped that. I used one heavy coat, then touchup
Click to expand...

how did you shield the blade from the oxidation at those temps? Also what hardness did the blades end up at? Those blades could very well be to hard for what you want which would increase grinding difficultly. Last but not least what thype of belts are you using and grit. Need to use good new ceramic belts and swap them out when thy get dull. Don’t get AEB-L confused with nitro V. Thy are completely different and made by different manufactures.
 
I tried ATP-641 and another product from ATP. I got similar results. I went back to foil.

Seems like other people like ATP-641, maybe it was my process, but I couldn’t get good results, when compared to foil.
 
TILLER said:
I tried ATP-641 and another product from ATP. I got similar results. I went back to foil.

Seems like other people like ATP-641, maybe it was my process, but I couldn’t get good results, when compared to foil.
Click to expand...

Yeah, when I use foil, it behaves very much like the 52100 and 15n20 that I use on most of my knives.
Prob. just way, way harder than I'm used to- I'm aiming for 60-61 for this style of knife, and it's quite likely much harder- I don't have access to a tester at this time, the facility I usually use is closed til covid settles down.
I had high hopes for the ATP, kind of weary of buying and folding foil packets, and tearing them off when done :)
A higher temper helped quite a bit.
 
1950f is peak austenitizing, reduce your austenitizing temp to 1900f and increase your temper to 350f to reach 60-61rc.

Confirm with hardness curves if a specific Hardness is desired, minor differences in batch to batch chemistry, HT furnaces and hardness testers, operators and practices may have variation in the results you get so it's always best to characterize it yourself.


elementfe said:
Yeah, when I use foil, it behaves very much like the 52100 and 15n20 that I use on most of my knives.
Prob. just way, way harder than I'm used to- I'm aiming for 60-61 for this style of knife, and it's quite likely much harder- I don't have access to a tester at this time, the facility I usually use is closed til covid settles down.
I had high hopes for the ATP, kind of weary of buying and folding foil packets, and tearing them off when done :)
A higher temper helped quite a bit.
Click to expand...
 
DeadboxHero said:
1950f is peak austenitizing, reduce your austenitizing temp to 1900f and increase your temper to 350f to reach 60-61rc.

Confirm with hardness curves if a specific Hardness is desired, minor differences in batch to batch chemistry, HT furnaces and hardness testers, operators and practices may have variation in the results you get so it's always best to characterize it yourself.
Click to expand...
Thanks, I'll give that a try next batch.
I've been reading and rereading Larrin Thomas's articles on this- he's a mythbuster for sure!
 
E.Carlson said:
Did you say oil quench? These are both air hardening steels.
Click to expand...
Every alloy has a set of parameters in terms of ideal cooling time and temp for a desired outcome.
How you accomplish that task is negotiable.
Yes, both steels are commonly air hardened....but most knife makers plate quench them.
 
Your protocol looks like mine for AEB-L, but I freeze to -40 and use foil and plate quench. I get 62 Hrc consistently with that. I get a little discrete pitting with AEB-L, none with my other steels (RWL-34 and 14c28n).
I have absolutely no problem grinding it post heat treat. House belt is Bora7.
 
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Scaniaman said:
Your protocol looks like mine for AEB-L, but I freeze to -40 and use foil and plate quench. I get 62 Hrc consistently with that. I get a little discrete pitting with AEB-L, none with my other steels (RWL-34 and 14c28n).
I have absolutely no problem grinding it post heat treat. House belt is Bora7.
Click to expand...

Curious- how do you get -40, is it an electric freezer set way low?
I'm using a variety, my go-to problem solver is a new 36 or 60 3M 984...it pretty much failed on these blades when tempered in the low 300s. First try was 300, then 325. 375 was better.

The big thing about this was that I followed recommendations and was meticulous about maintaining a continuous cooling curve, no resting at ambient temp.
I had had no idea how much that affects the finished product, it's profound.
If you read Larrin's articles, it's plain that you can make a darn good blade using a household freezer, if you use the correct temps and continuous cooling.
 
Yes it is a household freezer that can be set to speed/turbo freeze mode for 48 hrs or something. It goes to -45 with a small load. -40 with more stuff in there. With this kind if freezing I get AEB-L to 62 hrc, RWL-34 to 63.5 hrc and 14c28n to 61-62 Hrc. Plenty good, but I am interested to try colder too.
 
elementfe said:
Every alloy has a set of parameters in terms of ideal cooling time and temp for a desired outcome.
How you accomplish that task is negotiable.
Yes, both steels are commonly air hardened....but most knife makers plate quench them.
Click to expand...
Yes, by air hardening I meant plate quench, but you said oil quench in the original post.
Did you plate quench or oil quench?
 
Our -86°C freezer will pull 64-65rc out of aebl with our schedule.
 
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