Aeb-l didnt harden

S

Shipshores

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Apr 2, 2016
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I heat treated two 1/8" thick aeb-l knives in my evenheat oven at 1975 deg f for 10 min. They were in a foil pouch. Neither one hardened. Ive treated the some knives from the same bar of steel using the same settings without issues. Any ideas? Oh, i placed the knives inbetween aluminum plates and used compressed air.
 
Were they in the same pouch?


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"Didn't harden" - what method did you use to determine they were not hard?

Did you grind the edge a bit to see if there was hard steel under some soft decarb?
Use a Rockwell tester on a freshly ground spot?
Run a file down the edge?
 
Yes i had both in the same pouch. Stacy, I can bend it easily and it stays bent. I tempered at 350 f for 2 hours. Ive had problems with 440c before as well. I'm thinking it mite be my oven at the upper temps. It seems to be hit or miss with stainless. I mite have to build or buy a pyro meter to double check temps but was wondering if it could be something else.
 
What I have luck doing is one per pouch, ramp the temp with blade in oven to 1950 2 min soak, plate Q with pouch, shoot air in from the sides, never have had a problem.
 
Ok, thanks. I'll try one per pouch. My soak time is 10 min at 1975. I'll stick with that and one per pouch and if that doesn't work i'll do a 15 min soak. My oven is 110v, not sure if that has anything to do with it heating up or the thermo is off.
 
Your 10 minute soak is OK, but it should first be taken to 1900-1925F for 10-15 minutes, then quickly ramped to 1970-1975F for 10 minutes.

That still doesn't explain the super soft situation you have. What type of oven are you using? Is it a small jewelers burnout oven or pottery kiln? If so, those don't ramp fast enough, or reach the higher temps well. For stainless HT you need a proper HT oven.
 
Soak time is short, I agree. You need the steel at that temp for 10 minutes, not the oven at that temp for 10 minutes. I'd run it just like you did, but bump it to 20-30 minutes and see if that works. Stacy's plan is good as well.
 
I have a evenheat 22.5 . I will try the longer soak time. 1970 is almost the limit of my oven. I think it goes to 2000 -2200.
 
...is there really dissenting opinion on whether or not soak time is a concern when Hoss weighs in? Seriously?

Guys, please go back and reread DevinT's posts regarding heat treat. I doubt there's folks at B-U that have as much time with this stuff as Hoss does.
 
Better to believe what DevinT said... I think he has more in-depth experience with this steel than most knife makers in the world.
 
Stainless steels like aeb-l do not hold heat and do not heat up like carbon steels. It takes longer to get them to temperature.

Even though your furnace reads 1970', it takes time to get the piece up to temp. I use a half thick fire brick and preheat the oven for an hour before heat treating. I also have a seperate furnace that I preheat in before transferring to the oven at full quench temp.

Having two blades in the same pouch will slow the heat down quite a bit.

I have done hundreds of blades and hundreds of test coupons in this material.

Your blades are under hardened because of a lack of enough temperature.

Nathan recommends over heating the furnace and resetting the temp after the blade is placed in the furnace. I've started doing this and find that it is very good for small furnace heat treating.

Hoss
 
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^ I agree...

I preheat my knives in one oven and let the main oven cycle for a long time before I use it... think of a steak cooking at 5OOF for ten minutes, it would still be cool in the middle.

Pay attention to your colors as the knives get hot, sometimes just eyeing them will tell you a lot about the heat.
 
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