forging laminated steel

[Scott Roush]

For those of you who are forging... have you ever, or is there anybody in the USA who hand forges Swedish style laminated steel? I'm talking about the stuff that consists of hardened steel sandwhiched between two layers of mild steel.

I'm curious about the process....

[Lin Rhea]

Sure. Lots of the forged guys make this kind of laminated steel. It's called sanmai, although like so much, the name, being Japanese, has a broader meaning in actuality. But in this country sanmai is commonly a piece with 5 or 7 or less layers.
    By the way, I think you mean high carbon steel, when you said hardened steel. My every day carry is a Ray Kirk sanmai, it's one of his pocket medicine blades. The center layer is 52100, extending down to the cutting edge.
      The process is the same as any damascus, except you have to position the high carbon layer so it forms the edge. Good question. Lin

[kbaknife]

I specifically went to a hammer-in over in Ohio this fall to learn how to do that exact thing.
I'll be using 1095 as a core and 416 stainless as the outside.
Stay tuned!

[Scott Roush]

Yeah Lin.. I did mean high carbon for the core.  I was reading about how the Swedes, in the last century or so, revived their age old process of forging like this and I got fascinated.

That's great Karl.... Looking forward to hearing what you learned.

I don't forge yet, but, someday...

[Lin Rhea]

Karl,
      I hope to pick up a few things about that very thing. It sounds like it could be useful. Lin

[Wampus]

Here's one I made a couple of years ago, 5160 core between layers of chainsaw damascus.  It had some flaws and the handle felt just awful in the hand.  Was going to break it to see how strong it was but my nephew saw it and claimed it.

 

[Doug Campbell]

Hey Karl, how different is the SS/Carbon welding process from just Carbon/Carbon?

[Scott Roush]

Also Karl... if you didn't want to use stainless as the outer layer, what would be suitable as the 'mild' steel?

[kbaknife]

Scott, it's not so much that you want a "mild" steel skin, it's that you want it to be rust resistant - which seems to be the most desired facet of current consensus.
Doug, it's a dry weld, in that no flux is used.
Surfaces need to be REALLY clean on the 3-part "sandwich". Then, rolled up in numerous layers of SS heat treating foil. This is so the layers will survive about 17 minutes up at welding heat.
Then the billet is pulled from the forge and welded.
There's actually very little "forging" done to the billet afterward. We want to keep the outer layer at a consistent distance from the edge. When you have a billet up to forging heat, the core will sort of squirt out, which is where you get the core "out" at the cutting edge.
Then, as you sloooooooooooowly forge and grind, you need to pay attention to where the skin is going and where the core is going so you end up with the desired blade.
I think a person had better be emotionally prepared for a LOT of failures, both in welding and in consistency of san mai.

[Scott Roush]

Karl... From what I've read about the Swedish style laminated steel, the idea is that you have blade that is very easy to sharpen and more durable.

This is from the description of a Frost laminated blade:

"The core of the blade is high carbon steel surrounded by a softer alloyed steel layer. A high hardness (HRC 61) can be achieved through hardening, resulting in blades with superior thoughness and cutting edge retention, thereby maximizing sharpness and long life."

However, I can also see the value of using the lamination process for providing a stainless outer shell with an 'easier to sharpen' core for the edge.

[Doug Campbell]

Figured it had to be sealed, I thought about making the "sandwich" and tig-welding all the way around to seal it up.

Where did you come up with the 17 minutes and approx what temp is welding heat for SS?

Looking forward to your report on how it goes...

[kbaknife]

The laminating process has nothing to do with the ease of sharpening. Having the outer "jacket" does not alter the hardness nor alloy of the center core.
The reason the outer layer stays soft is because it will not austenize and doesn't have enough carbon to harden when quenched.
The paragraph you have quoted is just marketing lingo.
The first sentence "The core of the blade is high carbon steel surrounded by a softer alloyed steel layer" is exactly what I described in my first reply.
By "softer" they mean it is not hardenable. They're saying this results in toughness. Ok.
Depends on WHAT that alloy is!
The benefit of the stainless "jacket" is that it adds rust resitence to the package.
There would be no reason to stop at a tough "jacket" when you could add rust prevention as well.
And, it makes a great contrast!

[kbaknife]

What REALLY adds toughness is to leave the center core exposed on the center of the spine!
Rather than wrapping a complete jacket around the center core, you just make a three part sandwich leaving the core exposed at the top.
When the blade is quenched, we get partial martensite down through the top of the blade. This adds strength to the spine, rather than leaving it dead soft.
Some guys put in a stainless center core right where the blade begins so that the hardening STOPS at the blade/tang junction and leaves the spine drillable and fileable. etc.
Makes a nice look.
Lots of ways to go about it.

[Scott Roush]

Karl.... I'm not trying to argue with you... I just want to understand this.

I was lead to believe that the ease of sharpening of the non-stainless type of Swedish laminated steel had to do with the fact that since the outer layer is softer, then you have less hard steel to grind through when honing/grinding.

And here is another quote... Bo Bergman 'Knifemaking' a book about making Scandinavian style knives:

"... laminated blades are composed of two different materials. The internal blade is made of a thin sheet of edge steel, or hard steel, that has been hardened twice to approx. 58 Rc. The sides of the blade are then covered with sheets of soft iron and the entire piece is forged into one unit. The edge steel (core) is very hard and has a high carbon content, and the soft iron sides protect the hard center steel; thus, the knife blade is not fragile, but has high durability. This process dates back to the Viking blacksmiths, a tradition that is thousands of years old."

I guess he is saying the core is brittle and breaks easy and the soft shell does not... therefore more durable.


So is there anything to this or perhaps the thinking is outdated?  And perhaps, since many of the Swedes are now making stainless blades... they are now using a process similar to what you are describing.

Anyway... As you've probably garnered from my posts, I'm pretty fascinated with Nordic knife making and I'm just trying to understand it a bit better...

[kbaknife]

Originally posted by Doug Campbell:

Where did you come up with the 17 minutes and approx what temp is welding heat for SS?

That is the time that was arrived at by Bill Wiggins and Burt Foster.
That is the ENTIRE time - including warm up time - that the billet was in the propane forge.
The billet was placed in the forge at the same temp as regular welding temp - 2200-2400 - and then the timing began.
At 17 minutes, the billet was removed and welded.
TIGing all the way around would probably be a good way of doing it. After the first weld was done, I would let it cool off and grind off the weld.
Maybe have two billets made up so that while the first one was cooling off, you could be welding up the second one.
You might double your learning speed this way!??!
AS soon as you observed something working or not working on this first billet, it could be immediately dealt with on the second billet.

[kbaknife]

Originally posted by mossanimal:
Karl.... I'm not trying to argue with you... I just want to understand this.

I was lead to believe that the ease of sharpening of the non-stainless type of Swedish laminated steel had to do with the fact that since the outer layer is softer, then you have less hard steel to grind through when honing/grinding.

.

I realize that.
The point is that when this thing is forged down, the core SQUIRTS out from the sandwich. As you forge down your blade taper toward the edge, the center core ends up "OUT" there all by itself. There is NO "skin" there with it. The hardenable core is ALONE.
I think you believe you are sharpening all three of these "PIECES".
Hard steel is HARD steel - no matter what surrounds it. It doesn't make it easier to sharpen.
If steel was really easy to sharpen, it wouldn't hold an edge - would it?
I'm going to copy another maker's blade and post it here so you can see what I'm referring to.
What is sticking out here is plain ol' 1095 fully hardened. It sharpens just like a blade made of 1095 all by itself.
 

[Scott Roush]

That makes sense.... I just took a close look at my Frost Mora blade (laminated high carbon - not stainless) and you can see a similar thing along the edge.

So.... what is the benefit of the Swede's process then???? A lot of people make a big deal out of the Helle and Frost blades...

(btw.... thanks a lot of engaging in discussion with a rank newbie on this stuff)

[kbaknife]

Are you suggesting that the "Swede's process" is somehow more beneficial than the one we're discussing here?
It's the same process.
Some people like Fords. Some people like Chevys. And some people like Saabs and Volvos..
I suggest that the people who "make a big deal out of the Helle and Frost blades" probably work for Helle and Frost.

[kbaknife]

Originally posted by mossanimal:
That makes sense.... I just took a close look at my Frost Mora blade (laminated high carbon - not stainless) and you can see a similar thing along the edge.
 

What you are looking at there is MARKETING!

[Scott Roush]

Maybe the same sort of process... but different materials.  The process I'm referring to uses what is called 'soft iron' on the outer layer. You are talking about using stainless. I understand the benefit of the stainless process you've been talking about... That makes a lot of sense... But what I'm trying to understand is the idea of using the 'soft iron' outer core and the hardened inner core... the process that has made Swedish blades famous.  In other words... why are the high carbon (non-stainless) laminated blades from Sweden considered so good by so many people?

Maybe it is just marketing....  I dunno... I'm obviously in over my head here!