Nasa Icing courses

George Patterson writes:


"So why not build the shaft entirely of hardened steel?", I hear you cry. That's
because the harder steel is, the more brittle it becomes. The best strength
comes from this sort of lamination of hard and soft steels.

Saw a show w/ a Japanese craftsman making a sword. Two layers of
different steels. Pounded it thin; folded it over; pounded...
Many layers later, that was the sword...

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David Lesher wrote:

Saw a show w/ a Japanese craftsman making a sword. Two layers of
different steels. Pounded it thin; folded it over; pounded...
Many layers later, that was the sword...

Yep, that's a very old technique. Westerners call it "Damascus steel."

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

George Patterson wrote:
David Lesher wrote:
Saw a show w/ a Japanese craftsman making a sword. Two layers of
different steels. Pounded it thin; folded it over; pounded...
Many layers later, that was the sword...

Yep, that's a very old technique. Westerners call it "Damascus steel."

Got a knife made using that technique. Beautiful grain, sort of like a
nice gun stock made with multiple layers of different wood, beautiful
when carved.

The Monk

On Sun, 8 Jan 2006 19:41:33 +0000 (UTC), David Lesher
wrote:

Saw a show w/ a Japanese craftsman making a sword. Two layers of
different steels. Pounded it thin; folded it over; pounded...
Many layers later, that was the sword...

Right, but the entire blade is heat treated so that it is tempered,
rather than hard. If it were made from the kind of steel that
camshafts were cast from, it would be very brittle.

Not many camshafts, in low rpm engines, require forged camshafts,
there just isn't much pressure on them because they spin so slowly and
the valve springs aren't very stiff. But all camshafts require heat
treating the outer layer, or they'd wear out very quickly.

Corky Scott

wrote:

Right, but the entire blade is heat treated so that it is tempered,
rather than hard. If it were made from the kind of steel that
camshafts were cast from, it would be very brittle.

No, David had it right. Japanese cutting tools are made by laminating hard,
brittle steel with soft, mild steel. The best place to see this these days is
chisels or plane blades. There are only two layers in these; the outside layer
is very hard and the inside very soft (for tool steel, that is).

This has the disadvantage that the cutting edge is much more easily damaged than
that of a western blade. It is, as you point out, brittle. They were never
designed to be used in buildings with concrete floors or environments that
include nails.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.