San Mai cladding steel: 410 vs 416

[Karl B. Andersen]

I also recently did a Brute de Forge with the forged guard which is forged out laterally to show the integrity when done correctly.
I have also done everything I could possibly think of to destroy a San Mai blade and finally quit from exhaustion.

 

[Karl B. Andersen]

I'm going with "A". When we etch hardened tool steel with a bit of manganese it etches pretty black. Which is why I use 1095 in my San Mai.
When I etch my blades when I have clayed the ricasso, the choil area and on top of the ricasso etch gray, meaning they never hardened because they didn't get to austenite.
I don't really in this case that my ricasso did not get hard, because stainless is so friggin' tough, done cerrectly, these type knives are almost indestructible.

Karl, what do you think the clay does in this case, "a" or "b"?
a) prevent the core to get to full austenitization in the ricasso/ avoiding the nose in case of full aust., during the quench
b) Keeping the ss cladding hot enough for a while to move some together with the core at the clay area during conversion at the quench

 

[Karl B. Andersen]

Since this conversation seems to be going on, I will also point out that I use 3/8" thick 1095 and .270" stainless on each side.
Alloy/carbon migration happens at WELDING HEAT if it's going to happen at all during things we makers do.
And because of this, I want to stay at welding heat as long as I possible can. And I want my billet under the press and hammer as many times as I can make it happen.
I want that steel to become ONE.
And it does.
It's also a reason why you see so many layers of migration in my etched blade.
Many guys do the "wham-bam, thank you ma'am" san mai weld.
They start with three layers of steel that when all put together are nearly at their final dimension!! As such, they spend very little time at welding heat and also experience a lot of welding failure.
I do not say this lightly - I have never - EVER - had a welding failure with my method. And I have made a sh** pot full of San Mai, and taught a few of the guys out there selling it.
Also, I think the title "San Mai" is misused quite a bit.
Fella takes three layers of something, welds 'em together and call them 'San Mai'.
The idea of San Mai is that it is a tool steel core surrounded by a differential jacket for toughness or rust resistance.
That is NOT putting 203E on W2, or 15N20 on 1084, etc.

"San Mai generally refers to knives with the hard steel hagane forming the blade's edge and the iron/stainless forming a jacket on both sides. In stainless versions, this offers a practical and visible advantage of a superb cutting edge of modern Japanese knife steel with a corrosion resistant exterior. In professional Japanese kitchens, the edge is kept free of corrosion and knives are generally sharpened on a daily basis. Corrosion can be avoided by keeping the exposed portion of the non-stainless portion of the blade clean and dry after each use."

The stainless is used for corrosion resistance and the "iron" (wrought iron) is used because it will not harden and it offers differential properties.

As a complete aside to this, the term Brute de Forge has become totally bastardized as well, to the point that anything left with a little forge scale on it is now called BdF, when, in fact, forge scale is only a matter of forge atmosphere and has nothing to do with the PROCESS of forging at all.

 

[jdm61]

Ah. So time to buy some of the super duper high temp foil? I used the regular stuff with kerosene inside to do a couple of Ferry flip bllets a while back so that I could get away with just lightly tack welding the sides of the tiles together. It worked well, but lets just say that after the second welding heat and pressing, the foil was kinda ready to flake off onto the floor. Once you get everything properly stuck together can you forged it down pretty thin as long as you keep the heat up?

You can't use flux with stainless, Joe.
I wrap my billets in stainless foil.

 

[javand]

Yes 410 or 420 are preferable to 416, regardless, make sure it's from a trusted source. I've had supposed 416 and 410 that etched black, from a "reputable" vendor.


There is even a higher carbon version of 420, although I've never tried it.


Personally, I just tig (without filler) or mig all the way around the seams, and let her rip.

 

[Karl B. Andersen]

The foil is only for the initial weld. After that it's redundant.
Lots of guys are now sticking their billet in a short tube of tail pipe cut-off. They press the ends together or weld them shut.
Squeeze to get the weld then cut it off.
Once you squeeze it after the first weld, none of that stuff is needed any more.
Get out there and weld some up and learn something.

Once you get everything properly stuck together can you forged it down pretty thin as long as you keep the heat up?

 

[jdm61]

Might be time to finally hook up my Uncle Al blown forge. Your input is appreciated as always, sir!!! :thumbup:

The foil is only for the initial weld. After that it's redundant.
Lots of guys are now sticking their billet in a short tube of tail pipe cut-off. They press the ends together or weld them shut.
Squeeze to get the weld then cut it off.
Once you squeeze it after the first weld, none of that stuff is needed any more.
Get out there and weld some up and learn something.