Gillstay
Veteran
No this is heavy, not for chopping mangle wurzels.
Swords
- Thread starter derrick
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No this is heavy, not for chopping mangle wurzels.
Reynard
Guru
- Location
- Cambridgeshire, UK
I think it's both, but it's a while since I've done any in-depth reading on the subject. IIRC, they use two different grades of steel, one for hardness (cutting edge) and one for strength (back edge), and it's where the two grades join.
I'm more than happy to have my perimenopausal brain corrected though.
Punkawallah
Veteran
IIRC, this is the video they have on ‘autoplay’ at Royal Armouries, Leeds. Flavour text ends at about 13 minutes, relevant bit starts at about 16 minutes:
View: https://www.youtube.com/watch?v=Tt6WQYtefXA
Profpointy
Legendary Member
You say that as if it were somehow a bad thing
Yellow Saddle
Guru
- Location
- Loch side.
It's good when someone is happy to be fact-checked. I lost a bit of money recently when I argued that a rabbit is a rodent. I was so cock-sure of my facts that I put down £20 (IIRC). I lost. Rabbits are not rodents. Your sword is not damascus. Damascus looks like this:
roubaixtuesday
self serving virtue signaller
Not at all, just checking I hadn't overdone the shrooms
OP
OP
derrick
The Glue that binds us together.
- Location
- On the edge of London
Punkawallah
Veteran
I live to serve :-)
Reynard
Guru
- Location
- Cambridgeshire, UK
Oh, thanks for that. I'll sit down and have a watch once I've got today's culinary endeavours out of the way.
Reynard
Guru
- Location
- Cambridgeshire, UK
My background is in research, both in engineering (strength of materials, but composites, not metallurgy) and in motorsport history. I'm used to saying "I'm not sure" or "I don't know" if there's a hole in my info - far better to admit it than not.
In this case, I do have books on the subject (metallurgy, arms & armour, Japanese swords), but they're on the garage loft and awkward to get to.
The hamon is the temper line, showing the differential hardening of the edge and the back of the blade. It is caused by clay painted on the blade before heat treatment. The purpose is for the the edge to be harder to take a very sharp edge, while the back of the blade is softer and more resilient. An entire blade heat treated to the hardness of the edge would be prone to breaking on hard contact.
Steel is hardened by heating up then quenching in liquid to cool it fast. For traditional Japanese swords water is used. Water cools the steel very quickly resulting in a harder, but often more brittle steel. In Western traditions quenching in oil is more common for swords for this reason.
The clay painted on the back of the blade slows down the cooling of the back of the blade, resulting in that portion being not quite as hard as the area which is left without clay. The edge cools the fastest so is the hardest part. The different patterns of hamon are characteristic of different makers.
The actual construction of the billet of steel which is forged into the sword varies by time period and sword maker. "Sanmai" i.e. 3 layer is a famous one. Another "kobuse" is where a high carbon steel jacket is wrapped around a low carbon steel core.
The folding was a way to beat out impurities and inclusions and spread the carbon content more evenly. A common misconception which has added to the mystique is that a sword with hundreds of layers was folded hundreds of times. But in reality folding only ten times gives over a thousand layers, 2 to the power 10.
Steel is hardened by heating up then quenching in liquid to cool it fast. For traditional Japanese swords water is used. Water cools the steel very quickly resulting in a harder, but often more brittle steel. In Western traditions quenching in oil is more common for swords for this reason.
The clay painted on the back of the blade slows down the cooling of the back of the blade, resulting in that portion being not quite as hard as the area which is left without clay. The edge cools the fastest so is the hardest part. The different patterns of hamon are characteristic of different makers.
The actual construction of the billet of steel which is forged into the sword varies by time period and sword maker. "Sanmai" i.e. 3 layer is a famous one. Another "kobuse" is where a high carbon steel jacket is wrapped around a low carbon steel core.
The folding was a way to beat out impurities and inclusions and spread the carbon content more evenly. A common misconception which has added to the mystique is that a sword with hundreds of layers was folded hundreds of times. But in reality folding only ten times gives over a thousand layers, 2 to the power 10.
Reynard
Guru
- Location
- Cambridgeshire, UK
Every time you fold, it doubles, so 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 etc.
Punkawallah
Veteran
But somehow you never end up with a swan?
Drago
Legendary Member
- Location
- Suburban Poshshire
Did you know that the secrets of Damascus steel have been lost and no one really knows for sure today how it was made? At best we can only approximate it. In any event, the Japanese nihonoto steel knocks it into a cocked hat.
PS, I also thought rabbits were rodents until I had a similar friendly argument with so eone a couple of years ago.
There's a difference between what Damascus steel generally means these days, "pattern welding" whereby different grades of carbon steel and/or iron are forged and twisted together, creating swirling or regular patterns. The construction methods are well understood and quite a lot of sword makers are making authentic recreations of early medieval swords in this way.
Damascus originally referred to a type of steel made in a crucible, also known as Wootz steel and originally made in India. It has been recreated but it's true to say the precise methods aren't fully known.
The patterns in true Damascus crucible steel are more random and usually finer grained. In pattern welding they are usually regular and repeating.