Differential hardening

Charles,
Sorry but my news reader erased your post before I answered so I am writing this from memory.
You are correct that a two step tempering process probably would not
leave a "temper line" as the condition of the steel would change gradually.
But, given that many of the Japanese blades are made from two different grades of steel how much of the temper line is a result of the tempering process and how much is a result of the different grades of steel welded together to make the blade?
--
Cheers,

Bruce in Bangkok
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Bruce in Bangkok wrote:

The temper line is caused by the clay hardening technique. You can achieve this line even if you use a homogenous alloy for your blade.
I can put you in contact with Pierre, who is currently an apprentice in Japan, to discuss this further, as he has far more practical experience than I do in this technique. A very interesting person to talk to. I was able to get a cool book through him on Japanese swords and their manufacture signed by the author.
Regards Charles
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Yes. :)
Off hand, many have said that it needs to be a very clean (low P) straight carbon steel to get the line. I've wondered what W or V would do to the ability to get a nice line since they can make an otherwise straight carbon steel even more shallow hardening.
You'll see W and/or V mentioned ever'once in a while as helping with making a steel deeper hardening (slow things down) but it's usually just wrong information copied over and over. :/ Two ways W and V can make a steel more shallow hardening is first: finer grain size and the second: tying up enough carbon to make the steel act like a lower than expected carbon content.
Alvin in AZ
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snipped-for-privacy@optushome.com.au says...

Nah, I'm not going to be tempering anything - at least I don't think I am.
What knife making I do is confined to making "work knives". Usually small with a blade length of about 2 inches and a handle about 2-1/2 inches. I can buy HSS hack saw blades fairly cheaply (and get two knives from each blade) so am happy grinding out a blade with a 4" hand grinder and epoxying on a teak handle. they are reasonably easy to sharpen and stand up well to what I use them for - cutting glass cloth, ropes, etc.
I had thought about getting a decent folding knife, or kit, but they, and the shipping, mean I could make a bucket full of knives for the cost of a single imported knife I have decided not to bother. I must have a dozen of the HSS knives scattered around, rigging knives, bench knives, pocket knives...
By the way, the little knives don't have a long enough blade to let them stay in a soft sheath so have been making wooden sheaths. I found that the wooden sheaths fell off so inlayed some magnets from an old disk drive in the side of the sheath. Other then now having magnetic knife blades it works well. The sheaths are fairly loose but don't fall off because of the magnet.
--
Cheers,

Bruce in Bangkok
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Bruce in Bangkok wrote:

I'm interested in wooden sheaths, do you have any pictures?
Regards Charles
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Yeah, what CA said. :)

Wow! That's really nice work there, Charles! :)
How much kangaroo meat can you get for that one? ;)
Alvin in AZ
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snipped-for-privacy@Example.com wrote:

Depends where you get the meat :-D
A friend gets that one for a special price ;-) It's ready for use, this is one of the last ones, heat treated externally. It's set at 57 rockwell with a spring temper.
Thanks for the praise I do appreciate it.
Regards Charles
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