Formation of Excess Carbide Phase in Damascus steel

It is shown that the excess carbide phase in Damascus steel is of an unusual nature origin that differ 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 Damascus steel lies in the abnormal size of excess carbides having the shape of irregular prisms. Discovered that the faceted angular carbides are formed within the original of metastable ledeburite, so they are called "eutectic carbides". It is revealed that the eutectic carbides angular forms have a stoichiometric composition equal to 35% carbonatoms and 65% of iron atoms, which corresponds to the Epsilon-carbide Fe2C. Found that angular eutectic carbides in the Damascus steel formed during long isothermal soaking at the annealing and subsequent deformation of ledeburite structures. It is revealed that Damascus steel with is the carbon content in the region of white cast iron, no contains 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 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.