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simple carbon steel disastrous forging temperatures?


J.Leon_Szesny

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so once I'm done welding the carbon steel to the iron, what heats should I never approach, during the forging/shaping?

(other than the obvious forging it too cold or continuing to forge it at welding or sparking heat.)

what problems could it lead to? can I undo these problems with normalizations?

my current steel is shirogami 2 

compositon http://zknives.com/knives/steels/shirogami_2.shtml

 

PS:

I've been having a few bad runs with shirogami, before, I had used a high chrom moly steel..
been trying new techniques, which leads to new problems? 
3x normalized, coated with thin clay for better hardening, hardened in hot water, immediately tempered to 220C (430F) and broke during ura-dashi.

some had perfectly fine grain, some terribly big grain.
the ones with good and fine grain were worse, since I don't know why they broke.
(ura-dashi is where you lightly hammer on the iron to push the steel lamination downwards to form the cutting edge of japanese tools.)

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5 hours ago, J.Leon_Szesny said:

what problems could it lead to

I'll be interested to hear what other folks think, but I was taught that thing to worry about is burning off carbon, which happens at . . ., I don't know, but that it's better to get it really hot (2200F+) and forge in one heat than to forge at lower (1800-2000F) heats but take more heats to do it.  

RIP Bear....be free!

 

as always

peace and love

billyO

 

 

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Sounds like multiple variables at play here.  Like Billy said, welding heat as little as you can. At 1.2% C that steel is going to weld on the lower end of the temperature range. After welding, forge around 1900 F, never lower than 1800 F.

Normalize three times watching for decalescence over the whole blade. This will keep the grain size consistent throughout the blade.

Finally, what temperature is your steel during ura-dashi?  That's one of the more punishing things you can do to high carbon steel, and it has to be done with the steel around 300-350 degrees F or it will break every time. Also, you must keep the stresses evenly distributed. Don't hammer more in any one spot, and keep the blade hot enough to sizzle water on contact.

Finally, you must use really soft iron. Mild steel isn't soft enough. 

I have watched a few really good smith make yaganiba. It's always a tense few minutes watching the ura-dashi. :ph34r:

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4 hours ago, Alan Longmire said:

Sounds like multiple variables at play here.  Like Billy said, welding heat as little as you can. At 1.2% C that steel is going to weld on the lower end of the temperature range. After welding, forge around 1900 F, never lower than 1800 F.

Normalize three times watching for decalescence over the whole blade. This will keep the grain size consistent throughout the blade.

Finally, what temperature is your steel during ura-dashi?  That's one of the more punishing things you can do to high carbon steel, and it has to be done with the steel around 300-350 degrees F or it will break every time. Also, you must keep the stresses evenly distributed. Don't hammer more in any one spot, and keep the blade hot enough to sizzle water on contact.

Finally, you must use really soft iron. Mild steel isn't soft enough. 

I have watched a few really good smith make yaganiba. It's always a tense few minutes watching the ura-dashi. :ph34r:

ura-dashi is done on cold metal, you have to hold the blade/tool with your fingers, even with soft steel it can be done but iron is best, normally its pretty easy, some japanese smiths really beat the crap out of the iron of the bevel part, with no problems
and that's how it should be, if you didn't mess up somewhere, the steel should be able to take it without breaking.
but I messed up, somewhere!...

Edited by J.Leon_Szesny
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