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Traditional sword tempering?


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#1 Zoltan Csaszi

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Posted 11 March 2008 - 04:42 PM

Hi all,

The traditional Japanese sword making how the tempering method!? Charcoal, oil... :huh:

Regards,

Zoltan

#2 Mire Blades & Tools

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Posted 11 March 2008 - 10:30 PM

Hi all,

The traditional Japanese sword making how the tempering method!? Charcoal, oil... :huh:

Regards,

Zoltan



left the edge hard and back soft. mostly as quenched with clay coat from what i understand.
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#3 bubba-san

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Posted 12 March 2008 - 01:46 AM

As far as I know there were a number of different treatments involving clay or a clay like substance ,One comes to mind is charcoal ,charcoal ash and native clay mixed with water , to a consistency of a thin malt . First a very thin layer ,then a heavier but, still thin layer. I think the clay had a high lime content , which is probably why it sticks ! Bubba -san

#4 EdgarFigaro

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Posted 12 March 2008 - 02:01 AM

Seen some videos of modern day ones that just temper it by color back on the coals in the fire.
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#5 Zoltan Csaszi

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Posted 12 March 2008 - 05:36 AM

Hi all,

The traditional Japanese sword making how the tempering method!? Charcoal, oil... :huh:

Regards,

Zoltan


Excuse me! Confusion of ideas... Japanese sword making how the annealing method!?

Thanks!

Zoltan

#6 bubba-san

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Posted 12 March 2008 - 10:05 AM

to anneal most steel , heat your blade to 1500 degrees and let cool naturally in air. It makes metal easier to work .you can do this several times until steel looses color. I usually do several time, Bubba -san

#7 bubba-san

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Posted 12 March 2008 - 10:06 AM

to anneal most steel , heat your blade to 1500 degrees and let cool naturally in air. It makes metal easier to work .you can do this several times until steel looses color. I usually do several time, Bubba -san

#8 Zoltan Csaszi

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Posted 12 March 2008 - 11:20 AM

to anneal most steel , heat your blade to 1500 degrees and let cool naturally in air. It makes metal easier to work .you can do this several times until steel looses color. I usually do several time, Bubba -san


Hi Bubba-san,

Heat your blade to 1500 degrees and let cool naturally in air. This is not the normalisation? I can annealing a short blade in the oven, but a long sword... How me do it? :wacko:

Regards,

Zoltan

#9 Leif S

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Posted 12 March 2008 - 12:41 PM

Zoltan, annealing is almost the same as normalization, the difference is that the steel is cooled down over a longer period of time. This is done by covering the steel in an insulating material or by using a process controlled furnace. For shallow hardening steels like 10xx-series, W1 or W2 a couple of normalization circles is usually enough to relieve forging induce stress, but deep hardening steels like L6, 5160 or 52100 benefits greatly from a full anneal once the forging is done.

When it comes to heating long blades to critical temperature without a sword length furnace there is a technique called "fire stroking", basically the blade is moved back and forth through the forge until it's at an even temperature. Sounds easy enough, but it only gets harder the longer your blade is.
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#10 Leif S

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Posted 12 March 2008 - 12:43 PM

One more thing. The traditional Japanese sword steels,tamahagane and orishigane, are so shallow hardening that they don't need any normalization or annealing.
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#11 jake cleland

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Posted 12 March 2008 - 10:13 PM

ok. the confusion seems to be that Zoltan asked about tempering and recieved answers about hardening, so he assumed tempering is the wrong term and switched to annealing.

from what i've read, earlier blades were for the most part not tempered after the quench, as they were very low carbon by modern standards.

i think modern Japanese smiths now strive for an edge steel with between 5 and 6 points of carbon, and draw the blades back accordingly, by making a bed of charcoal, and covering this with a thick layer of ash, to protect the blade from direct contact with the heat. the blade is roughly polished on a coarse stone to show the oxide colours - its best not to touch the blade after polishing because skin oil will contaminate the oxide colours. the blade is layed on the coals/ash, and tempered until the colour just starts to change. in the craft of the japanese sword, it says the blade is quenched after this step, but if the temperature is not rising too rapidly, i think youd be better to let it cool in air. with high carbon steels i'd also be inclined to repeat this process a couple of times to make sure any retained austenite is converted to martensite and tempered.

so basically, temper over charcoal

use an insulating layer to even out the heat and protect the blade from direct heat (a heavy steel plate would also work)

watch your colours carefully, and if any part of the blade starts to turn a bronze colour, quench it in water and start over.

this is just from what i've read, hope it helps
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#12 Zoltan Csaszi

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Posted 15 March 2008 - 05:00 AM

Thanks Jake! :)

Regads,

Zoltan

#13 Zoltan Csaszi

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Posted 15 March 2008 - 05:01 AM

One more thing. The traditional Japanese sword steels,tamahagane and orishigane, are so shallow hardening that they don't need any normalization or annealing.


Thanks Leif! :)

Regards,

Zoltan

Edited by Zoltan Csaszi, 15 March 2008 - 05:02 AM.





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