How do they tell if the blade is made of wootz?

Ann Feuerbach · 29th November 2005, 06:25 PM

Hi Jens,
Lucky for us, it has been possible to identify some crucible steel objects, even if they have been to some extent corroded. Brian Gilmore determined that the sword from Nishapur in the Met was crucible steel (would not have had a pattern), and I found a few blades (and an ingot) that are. I have some very good evidence where we have a corroded area and an uncorroded area adjacent. Although the metallic metal has oxidixed (corroded), you can see the original structure in as ghost or relic structures in the corrosion products. Without going into the electo-chemistry (which I would need to look up) the pearlite or ferrite matrix has more surface energy and wants to corrode (get back to nature). However, the cementite is more stable, partly because it is spherical. This causes preferential corrosion. The matrix corrodes before the spheroidal cementite.
Word of warning...relic sturctures can also be seen in other types of corroded objects but corrosion can also cause new structues to develop. I have some good references on relic structues if anyone wants them.
This is also one reason why electrolitic reduction can be so damaging.
Ann

29th November 2005, 06:25 PM	#2
Ann Feuerbach Member Join Date: Feb 2005 Posts: 133	Hi Jens, Lucky for us, it has been possible to identify some crucible steel objects, even if they have been to some extent corroded. Brian Gilmore determined that the sword from Nishapur in the Met was crucible steel (would not have had a pattern), and I found a few blades (and an ingot) that are. I have some very good evidence where we have a corroded area and an uncorroded area adjacent. Although the metallic metal has oxidixed (corroded), you can see the original structure in as ghost or relic structures in the corrosion products. Without going into the electo-chemistry (which I would need to look up) the pearlite or ferrite matrix has more surface energy and wants to corrode (get back to nature). However, the cementite is more stable, partly because it is spherical. This causes preferential corrosion. The matrix corrodes before the spheroidal cementite. Word of warning...relic sturctures can also be seen in other types of corroded objects but corrosion can also cause new structues to develop. I have some good references on relic structues if anyone wants them. This is also one reason why electrolitic reduction can be so damaging. Ann