AEB-L bow after tempering

[Jrmysell]

So I heat treated a batch yesterday of different AEB-L kitchen knife blanks. They seemed straight after plate quench and coming out of LN. I tempered late last night and didn’t notice it then either but 2 of them (gyuto and sujihiki) both have a slight bow to them. Can I temper again tonight with the shim to try to straighten them or what can I do now that they’ve been tempered? I did 2 2 hour at 350*.

 

[TheEdge01]

Over correct the bow and retemper, it should come out straight.

 

[Hubert S.]

In my experience, there is zero chance this is going to work for AEB-L. I tried it quite a few times without success. A carbide peening hammer will take care of the bow very quickly, and you can also remove the new bow you are likely to get after initial bevel grinding before you move to a finer grit...

 

[Jason Fry]

Carbide hammer is great for that.

 

[Stuart Davenport Knives]

AEB-L is by far the most difficult steel I have every worked with when it comes to warping. Not to argue with Hubert, but it is completely possible to get it straight with the 3 clamp method (I have yet to make a carbide hammer). It can be frustrating, but it certainly can be done. The higher the tempering temp you use, the easier it is to correct, but I don't go over 300° with AEBL kitchen knives, and at 300° it takes a few cycles. The trick is to over-correct the opposite direction by the same amount (or slightly more) as the warp. Just clamping it straight won't be enough.

I am currently working on an 8" chef's knife that warped during tempering. I got it straight and then went to grind the bevels. It moved again. UGH!!!!!! It takes a few cycles, but eventually you can get it straight. I just finished putting the final polish on it this afternoon.

But definitely look into buying or making one of those carbide tipped ball peen hammers. I need to get off my butt and make one!

 

[Seedy Lot]

I think you will really appreciate a carbide a peening hammer. Pretty amazing at how well they work.

 

[Michael Black]

Carbide tipped hammer will change your entire world! Cannot recommend it enough.

 

[LCoop]

IF your going to use AEB-L you need to buy or make a carbide hammer. PERIOD IMHO

 

[Signalprick]

Carbide hammer is great for that.

I think you will really appreciate a carbide a peening hammer. Pretty amazing at how well they work.

Carbide tipped hammer will change your entire world! Cannot recommend it enough.

IF your going to use AEB-L you need to buy or make a carbide hammer. PERIOD IMHO

Boom! Problem solved!

 

[FredyCro]

Also peen after grinding to 80-90 percent as it is likely to move again, you will find yourself peening too often.

 

[Stuart Davenport Knives]

I just ordered a ball peen hammer and a 3/8" TC ball. Supposed to be here Wednesday and I can't wait!

You'd think as a kid who grew up in a hardware store I would have already owned a ball peen hammer, but nope!

 

[Taz]

I made 2 carbide hammers last week, took a few minutes to drill the holes and that was it. Found some 8oz ball peen hammers that were noted as "softer heads" online, so that made drilling easier (Vintaj brand). They are cheap and soft and wonky, but work great for my purposes! I ended up using tile/stone drill bit and a glass spade bit to drill out a pocket and then put the 3/8" balls into the hole to see if the hole was deep enough. It was, but the balls were stuck in the head, so I hit them a few times on wood and then metal and they self seated. If they come out, I will epoxy them in. They aren't perfectly centered and the heads themselves are a bit wonky, but they work really well, better than the one I made from a broken off and ground down carbide drill bit. $33 for 2 carbide straightening hammers is a no brainer! I will probably do up a couple more for some friends of mine!

I straightened some Magnacut, Cruwear and some other steels as well. I use a lot of AEB-L and Nitro V, so the hammer is great to have around!