Folded Steel Swords?

G

GarageBoy

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May 23, 2003
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Is there a name for the Japanese steel that has been folded over, forged numerous times to form a layered steel?
 
Yep it's called...steel.
The Japanese steel that was used for making swords was called tamahagane. It was tamahagane whether it was in little pieces, in simple billets, in fully formed sunobe, or in finished swords.

There are no special physical attributes that are gained through forge-welding processes. It remains the same steel it was before it was welded up. If you take paper and fold it, does it make better paper?

There are a lot of terms used to describe steel with physical layering...mechanical damascus, forge-welded steel, pattern-welded steel, folded steel, layered steel...the list goes on. The distinction only really serves to describe aesthetic opposed to pattern-less homogenous "monosteel" or ultra high-carbon "wootz" and others. More specific names are used to describe the patterns in the steel, not so much the steel itself. Random pattern, ladder pattern, mokume, masame, ayasugi, turkish twist, et cetera.
 
"There are no special physical attributes that are gained through forge-welding processes. It remains the same steel it was before it was welded up."

Yes and no. The gain is a higher carbon content in the steel.
the billet gets hot, and carberizes on the outside, as inn case-hardening. Then, fold, heat, and repeat. eventually, all of this folding and forge welding ups the carbon content throughout the steel.

Keithq
 
Thanks! I also heard that it makes swords more flexible, yet it can still be "hard" (sorry, lack of better word)
 
I do not completely agree with your statement about carburization as a direct result of forge-welding. You can gain carbon through direct contact with flame, regardless of whether or not you are welding the steel. Also, in many instances you lose minor amounts of carbon through normal forge-welding.

Also, as Kevin Cashen has clarified, forge-welded steel does not create alternating layers of hard-soft as some claim. It does not increase ductility of the steel or edge-holding. Flexibility has nothing to do with layering of steel, just a matter of design and heat-treat. Edge-retention is also reliant on those elements.

It's cool stuff, but it isn't something to hype up. There's enough hype in the blade industry as it is.
 
An example of a badly done pattern-welded sword would be the early Paul Chen Godfred swords, the pattern-welded Viking sword that appeared about 5 years ago. The heat treat was quite erratic as was, apparently, the actual forging, resulting in blades that broke in half, bent too easily, and various other horror stories. I was fortunate enough to pay attention to the complaints before actually buying one, much as I lusted after it.
 
I heard that you fold layers in the steel so it may become more sharp, you sharpen microscopic layers of steel rather than solid steel. It seems that could be true, but is it? Someone set me straight.
 
Brianith,

I'm not certain where that idea comes from...when you are sharpening steel, you are removing surface material by scratching it. On a microscopic level this leaves jagged little edges, regardless of what type of steel it is, or if it has physical layering. The finer the stone you use, the smaller those "jaggies" get. Every steel *can* take an extremely sharp razor edge, though annealed steel will not hold it like hardened steel will obviously.

In steels like wootz with lots of carbides in a pearlite matrix, you have alternating bands of very very hard tiny particles (the carbides...vanadium carbides can exceed 80RC, compared to about 60RC for tempered martensite) and relatively soft steel intersecting the edge. When sharpening this stuff, the soft bands will be affected more than the harder bands, resulting in a very very aggressive "toothy" edge. This is why wootz (old school damascus) was so revered for its cutting abilities against flesh.

But, with pattern-welded steel, you do not have bands of alternating hardnesses unless you use something that does not harden (such as nickel). When you sharpen this stuff, you also get that minor serration effect, but the material does not get *sharper*.

Every steel can be sharpened so that it cuts aggressively. It is not a feature exclusive to pattern-welded steel or wootz.

You should probably not think of the layers as distinctly separate. Optimal pattern-welded steel will act as a single piece of steel.
 
Originally posted by Ferrous Wheel
"There are no special physical attributes that are gained through forge-welding processes. It remains the same steel it was before it was welded up."

Yes and no. The gain is a higher carbon content in the steel.
the billet gets hot, and carberizes on the outside, as inn case-hardening. Then, fold, heat, and repeat. eventually, all of this folding and forge welding ups the carbon content throughout the steel.

Keithq
Click to expand...

Most forge welding decreases the carbon content rather than increaes it. Most contemporary Japanese smiths start with a very high carbon content and stop folding when it gets down to around 0.6%. They are able to retain a relatively significant amount of carbon due to the slurry which protects from decarb.

Many American bladesmiths lose carbon with every heat, thus ending up with a steel that is harder in the center and softer on the edge.

Daniel
 
yeah, it was a point-heavy beast. I prefer historical repros in weight and fit.

KSteel--thanks fer that clarification. I thought carbon AND steel were lost in the forging process, though, not just carbon. Also, with case hardening, the outside of the blade does increase in carbon content, whereas the core does not.

Keith
 
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