Wootz: Cast Iron or Steel?

Abstract

It is shown that the excess carbide phase in Wootz is of an unusual nature origin that differs from the excess phase of secondary cementite, ledeburite and primary cementite in iron-carbon alloys. It is revealed that the morphological features of excess cementite in Wootz lie in the abnormal size of excess carbides having the shape of irregular prisms. It is discovered that the faceted angular carbides are formed within the original of metastable ledeburite, so they are called "eutectic carbides". It was found that angular eutectic carbides in the Wootz formed during long isothermal soaking at the annealing and subsequent deformation of ledeburite structures. It is revealed that carbon takes up 2.25% in Wootz (in the region of white cast iron), while none in its structure of crushed ledeburite. It is shown that the pattern of carbide heterogeneity consists entirely of angular eutectic carbides having an irregular trigonal-prismatic morphology. It is shown that Wootz (Damascus steel) is non-alloy tool steel of ledeburite class, similar with structural characteristics of die steel of ledeburite class and high-speed steel, differing from them only in the nature of excess carbide phase.

Formation of Faceted Excess Carbides in Damascus Steels Ledeburite Class

“…Refs. [10][11][12][13][14][15] show that large angular excess phases faceted eutectic carbides formed in the course of long-term isothermal annealing of high-purity pre-eutectic white cast iron with an excessive phase in the form of ledeburite inclusions. Large particles of angular eutectic carbides are thermally stable phases in comparison with excessive secondary cementite [14].…”