I spent over 2 years forging various type of stainless steels, and came one undeniable fact..... forging stainless steel is for the most part, counter productive.  Stainless steels simply are not improved in any way via forging, and more times then not, catastrophic damage is the result.

   Your questions are examples of only two of the many issues/problems that occur when trying to forge stainless.

  There is no easy solution to either of your questions.  My recommendation is to leave stainless steels for stock removal knives, and forge those steels that lend themselves and/or can be improved through proper forging.  You are seriously handicapping yourself forging AEB-L, and more then likely producing a substandard blade/knife, versus using the steel for for stock removal blades/knives.      

  Part of learning to forge/Bladesmith.... is learning what not to forge.  😉   

Thanks Ed.  Learning what not to do is just as important as learning what to do.   I was thinking of scrapping the knives anyway.  They just werent looking right.  Your answer helped me decide.  

One follow-up question - are there steels out there that can be "improved" with forging?  I always thought ideas such as edge packing were debunked or am I misinterpreting you?

Thanks for the answer.

There are a number of attributes that can be made "better" with the proper forging and/or thermal treatments of steel.   "Edge packing" IS NOT one of them. 🙂  That horse died some time ago. 

  All things being equal, there are a number of steels out there that I believe can be improved via forging, provided things are accomplished correctly/with that idea in mind.  😉 

Almost invariably, in a forging stainless discussion, you will get at least one person who has some time in reading about richer alloy metallurgy, who will say that, after much practice and study, they managed to forge stainless with no detrimental effects.  But they are still missing the obvious question- with all the complications and troubles that have been already mentioned here, and quite a few more we haven't even touched on, what have you gained if the best you can say is "at least I didn't ruin it!"   

There are dozens of steels that you can forge quite effortlessly with no worries or hassles, and be able to say it is as good as when you started- and at a fraction of the cost.  Some folks would be impressed watching somebody dig a ditch with a teaspoon, I would just silently shake my head while leaning on a shovel. 

Not that there aren't reasons to forge stainless- cladding a stainless san-mai, quickly sizing large stock etc...  but it seems like a lot of trouble just to make a blade.  

I am going to have to respectfully disagree with Ed and Kevin. 

I have been forging stainless for years. back when I still did Ironwork I worked with Austenitic stainless's (304 316etc) those are a different beast, but you do need to work with then differently than mild I wreck a lot of work and messed some tooling figuring out how to work with it.

some time back I started to mess around with hardenable stainless and it is much the same. Thus far I have forged AEBL Nitro-V and damasteel and done it enough I feel like I have a pretty good control over the process and have overcome most of the issues. 

Forging stainless is miserable it is like hitting a brick, the temp window for forging is very narrow  (2100 down to 1800degf)  It likes to crumble at 2200 and crack at 1500 (if pushed to far). you cant forge to close to shape because the Decarb can be huge (all that chrome I think)  and you can not affectablely deal with it with out a kiln, preferable with some sort of atmospheric control (gas fired or purged).and as said there is no reason to forge it .. of course there is no reason to forge any blade .. yet we do. The cost of material is both a up and down side of forging stainless. I have forged a number of blades from damasteel for instance so far I have lost only one (I didn't wait long enough to go into the cryo and the integral bolster cracked) damasteel is expensive I can double the out put from a bar by forging and control the flow of the pattern. any ends or trimmings from the bar can be forged into paring knives, also you can not make integrals efficiently with out forging. and if you want to make stainless pattern weld, well you need to forge stainless. .. I guess there are a few reasons to forge it.

My process 1st I cheat. I slash cut the point and pre notch for the tang reserving the pieces to forge out small knives later. (mostly I forge kitchen knives from stainless) 2 soak the steel at temp for a min or two to let the chrome go into solution or it tends to get crackey, set forge for 2050 DEGF  and keep it hot return it to the forge twice as often as you think you need to..  3 post forging I do a 2100 deg (just bring it to the forge temp) Normalizing /equilizing heat from black I cool in oil. it is then into the oven for annealing @ 1300DEGF  for 4 hours and ramp to room temp over 6 (I run this over night most of the time.  For thin kitchen knives I do not do any grinding preheat treat.  I will profile grind the knives after annealing to make sure there are no stress risers and to double check for any cracking/ cold shuts.  I hardening in an argon purge oven with anti scale for AEB-L my schedule it ramp to 1100 argon on ramp to 1500 hold for 15 min, ramp to 1950 hold and quench in oil after 15 min.  Safest option is to cool until you can touch and snap temper @ 300 then cryo  followed by two more temper cycles. "better" option is to skip snap temper and into cryo once the blades are at room temp.. the only blades I have lost in heat treat were the second method .. 

My testing including destructive testing of these puts the performance pretty close to that of and in some cased exceeding that (in edge holding for instance ) of a really good carbon steel, but they also have the stainless properties.. 

MP 

Wow, that was an awesome reply Matt. I really want to try your process when i am a better smith and have a better way to control my temperatures.  A couple of questions - have you found any difference in forging nitro vs aeb-l? Also, for your first normalization are you cooling it in air first then putting in oil or is it like a quench that you do with carbon steels?  Lastly how thick stock are you starting and how thick do you take it to before  you quench?

Thanks for all the great advice!

nitro V is a little easier to move.. not easy but less stiff same temp window and it can be fussier in hardening.  The "normalizing" (more and equalizing )  I have been doing forge temp cool in air to around 1500 then into a slow oil to black and directly into an oven for annealing.  I dont know that the quench is needed but I found I was getting a bit less banding with it that with out.. that was  mostly in the Nitro V , that stuff can show banding no matter what you do , I have gotten it just as much in stock removal pieces. the quench doesn't seem to hurt and it speeds things up so I have continued doing it.. the quench may in fact not be necessary. I only do one, my understanding is the long anneal makes small spheroid carbide, setting up for hardening it is all that is needed .. in fact more is detrimental. 

for chefs I use 5/32 stock final thickness before grinding is 0.150 or so at spine and 0.050 or so at the edge I have done some out of 1/8 stock they finish out to thin , after grinding maybe 0.090 at the spine. 

I do all of the grinding post heat treat other than profiling. I find the decarb and scale to be a bit of protection from further decarb in the oven. (minimized further by  anti scale and argon purge)  I oil quench in slow oil , that seems to pop most of the tough scale off so the grinding isn't actually all that bad .. nice ceramic belt and go to town. 

MP