How wootz blades were forged?

[Ian]

Originally Posted by RobT

... Ian,
In her doctoral desertation (Crucible Steel in Central Asia: Production, Use and Origins), Dr Anna Feuerbach mentions a ring of glassious material inside the crucibles. If I recall correctly, Nonikashvili says that finding was the reason for his experiment. I wonder, however, about the possibility of any glassious material sticking to the steel of the ingot and being incorporated into the blade during forging. Even under low forging temperatures, that material should become liquid and run off the steel right away, no? I think that any SI content in the steel would be in the form of an alloy precipitate as the crucible charge cools. I am more than a bit unclear about this but, it appears from what I have read of Föll's monograph, it is the way in which the precipitates (C, SI, P, etc) are manipulated during forging that governs the strength/durability of the blade.

Sincerely,
RobT

Rob,

Thank you for the feedback. Interesting to know that glass featured in the manufacture of crucible steel. It is a while since I read Ann's thesis and I had forgotten that point.

I'm no expert on the history or properties of glass, although I think the old masters of wootz-making would have had silica glass available. In its finished state this is mainly an amorphous (i.e., non-crystalline) form of silica (SiO2). Thermal decomposition of silica glass can occur at sufficiently high temperatures and I don't know whether that happened during the making of wootz. According to Schwind (2002), depending on it's composition, some glass will melt at temperatures as low as 500 °C (900 °F), others melt at 1650 °C (3180 °F). As far as glass particles getting incorporated into the wootz, that seems at least a possibility, especially if these are sub-micron in size.

When discussing the Si content of wootz, I think Ariel was likely talking about an elemental analysis for silicon (Si). We don't know if the form of silicon present is elemental silicon, amorphous silica, one or more silicates, or some other chemical form.


Ian