[TheForge] welding heat, katana billets

[Andrew Vida]

On Thu, 31 Jul 2003 16:38:33 -0700, gladish <gladish@cnw.com> wrote:

> Also, Fiorini said to weld (when laminating) at the lowest heat 
> practical,
> to avoid damaging the steel, but the Japanese that I've seen on video 
> don't
> weld those katana billets until they look like a whole sixth grade class
> with sparklers on the fourth of July!
> Any comments on the difference?

	Bill may have been referring to the use of refined tool
	steels, whereas the traditional Jap. smith uses tamahagane,
	which is miserable material as it comes fresh from the
	tatara (smelter).  It is very large grained and the carbon
	distribution is extremely uneven.  The whole reason the
	Jap. smiths welded-folder-rewelded ten or fifteen times
	was to refine the grain and obtain greater homogeneity
	in the carbon distribution.  Also, welding at those higher
	temperatures would help reduce the overall carbon content
	down to about .7% which is considered a good place to be
	for this particular application.

	You don't want to burn the C out of engineered steels
	because when you do that, their properties alter, perhaps
	in unpredictable and undesireable ways.

> Apparently they lose about 2/3 of the original weight by the time it's a
> finished blank.

	I think this would vary between smiths.  I thought it was more
	like 1/3, but I'm old and halfway to happy, so you might be
	correct.  In any event, they do lose a lot of mass.  The more
	complex the construction of the blade, the more you will lose
	because you're into more heats.

	BTW, if you have never seen Bill do his thing, I recommend you	
	seize any opportunity to do so if one comes along.