Stainless with Hamon

How come no one ever does a hamon temper on a stainless knife? Seems like it would be a great match just aesthetically since the patina would never cover the hamon. Mostly I'm just curious, but I wonder if anyone has ever tried it.

chromium makes steels deep hardening and thus making hamons difficult if not impossible

*i'm sure there's more to it than just this and maybe larrin will chime in, but the gist of it is that deep hardening steels wont take a hamon easily or at all

JBroida said:

chromium makes steels deep hardening and thus making hamons difficult if not impossible

*i'm sure there's more to it than just this and maybe larrin will chime in, but the gist of it is that deep hardening steels wont take a hamon easily or at all

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Nope you've got it. Carbon steel can take a Hamon either through heating just the edge or by quenching a portion of the blade. Alternatively you could use a torch or similar method to temper back only the spine. The beautiful Hamon we're talking about is achieved by applying clay so that when the heated blade is quenched the clay coated portion cools more slowly. However stainless steels are all air hardening from the high chromium content so clay would never be effective.

Edit: the two torch methods used for more utilitarian "temper lines" are also difficult because chromium carbides require much longer soak times so you wouldn't get the edge properly austenitized without also heating the spine or with drawing back the spine you would also be tempering the edge.

Edit twice: when stainless steel is highly tempered (out of knife edge range) or not hardened, the stain resistance is reduced because more chromium is contained in carbides instead of in solution.

You can get a pretty darn funky, hamon-ish effect with stainless. But it is the effect of carbon diffusion from a high carbon core material into the cladding. That might not be so good for edge hardness, but you can achieve the effect and compensate by using a thicker percentage of core material, thus some carbon is sacrificial, the core of the core remains high carbon, one hopes. I have tried it with only thinner pieces and lost a good percentage of potential hardness. I'm sure with a good deal of practice you can get this effect just right and still have good hardness. I can't think of a better example than Bill Burke's stainless san mai's.
http://www.bladeforums.com/forums/showthread.php/935370-sanmai-stainless-and-52100-Sujihiki
Traditionally- the core is way to high, but who cares it looks like a frosty bad arse hamon... in stainless clad.

thats not the same as a hamon... thats what lamination looks like

Yes, but its a deliberate visual effect achieved with lamination. Effectively you have the highest carbon in the core, a transition and a soft spine. Different techniques, similar end result.

When you produce a more traditional hamon, is the clay applied to the blade before ever putting it into the furnace? Or is it added to a hot blade half way through to then be tempered down and quenched? I just wonder if you could do a clay coat at the beginning of a stainless blade's heat treatment and still allow it to air quench. My guess would be that you could still achieve a differential hardening effect, but that you wouldn't get that sharp beautiful line in the single piece of steel.

Thomas Haslinger claims to have done it.

http://www.haslinger-knives.com/differential-tempered.html

I don't know why it could not be done but I bow to Larrin as his PhD trumps my BS. :biggrin:

-AJ

I have seen Thomas' work first hand. He did achieve a temperline in S30V.

Yeah, if he said he did it, I believe him. He's been nothing but great to deal with and comes across as an honest and driven maker.
Now, whether or not differentially heat treating any kitchen knife is beneficial is, in my opinion, up for huge debate.

Lefty said:

Yeah, if he said he did it, I believe him. He's been nothing but great to deal with and comes across as an honest and driven maker.
Now, whether or not differentially heat treating any kitchen knife is beneficial is, in my opinion, up for huge debate.

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i think we can all agree that it's cool, though.

Yup, I put it in the same kind of category as damascus. It looks cool, and is another way for a maker to display his skills, but the actual benefit of such skill is likely none. BUT, I will say they have their place and I love both.

The only kitchen blades that I can see really gaining anything from differential HTing are meat cleavers (force used for many tasks) and (if a maker could zero in on the hardness/durability of a portion of the blade/edge) the third on the blade/edge at the heel of a deba. Now that would make me happy to see!

Thomas H. is a very smart and talented knife maker. The guy knows a lot about steel also.

I don't think that you can get an optimum heat treat and a hamon in stainless at the same time though. My guess is that he uses a torch to achieve the hamon.

Hoss

Phil Hartsfield was supposedly getting hamons with A2 (Air-hardening). No idea how he does it, but they don't seem faux.

With conductive heating/cooling, I guess hamon is possible albeit not practical. My newb hunts for stainless hamon would be:

Develope a stainless heat-equation for a specific blade params, write a simulation prg for conductives size/location/intensity varying temperatures & times. Most simplictic be 2 conductive plates (perhaps silver with platinum contact) soldered parrallel heel to tip seperated by a narrow insulator, torches + liquid N for thermal. Reckon lot of tries & errors before achieve a reasonable/usable diff HT hamon blade.

I was aware of the Haslinger knife, but the original question was about the attractiveness of the hamon, and the "clay-type" hamon would never work using traditional methods. I will be clear by saying that traditional methods for a temper line or hamon do not work. There are other ways to achieve a similar effect. I said that a utilitarian temper line is "difficult" but never said impossible. Also the original question was about avoiding patina to maintain the beauty of the hamon, but as I said corrosion resistance is reduced for the softer spine. Maybe this would be attractive, but not the same thing.

bluntcut said:

With conductive heating/cooling, I guess hamon is possible albeit not practical. My newb hunts for stainless hamon would be:

Develope a stainless heat-equation for a specific blade params, write a simulation prg for conductives size/location/intensity varying temperatures & times. Most simplictic be 2 conductive plates (perhaps silver with platinum contact) soldered parrallel heel to tip seperated by a narrow insulator, torches + liquid N for thermal. Reckon lot of tries & errors before achieve a reasonable/usable diff HT hamon blade.

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I'd try inductive HT first.

-AJ

I picked up 3 new knives from Heiji today (wowowow etc. Will post some first thoughts with pictures after i have had a chance to use them more, going on vacation Wednesday for a few weeks)

Here is a (small, would post better but this forum won't allow it unless I upload to external site) picture of the edge on the Suji.
Is this semi-stainless knife heat treated in a traditional traditional way or is the hamon achieved some other way?




Edit: Reading Jons reply below I need to do some more googling

thats a clad knife... the line is the lamination between the softer cladding and the harder core

Dieter01 said:

I picked up 3 new knives from Heiji today (wowowow etc. Will post some first thoughts with pictures after i have had a chance to use them more, going on vacation Wednesday for a few weeks)

Here is a (small, would post better but this forum won't allow it unless I upload to external site) picture of the edge on the Suji.
Is this semi-stainless knife heat treated in a traditional traditional way or is the hamon achieved some other way?

View attachment 8588


Edit: Reading Jons reply below I need to do some more googling

Click to expand...

You can upload to your profile first. Then use it as a separate web page also.