The morphology of the carbides in high-carbon alloys such as damascus steel

Analysis of changes in the morphology of carbides of the unalloyed high-carbon alloys such as damascus steel depending on the degree of supercooling of the melt, treatment and plastic deformation is conducted. It is shown that the crystallization process of the alloy with high carbon content (2.25 % C) at high degrees of supercooling is characterized by features typical for high-carbon steel. It is shown that the hot deformation of damascus steel with the structure of Widmannstätten cementite does not lead to its crushing. Plates of Widmannstätten cementite split into separate layers with a thickness 0.6…1.0 μm. However, the formation of such materials’ structure does not provide good cutting properties of the tool. Formation of ledeburite structure which is similar to ledeburite of white cast iron is found after high temperature annealing of the initial structure at 1150 °C for 2 hours. Two competing processes of forming proeutectoid carbides at strain of damascus steel, associated with spherodization and particles faceting, are determined. Three alternatives of the formation of eutectic carbides with faceted prismatic shape in iron-carbon alloys are considered. One of them involves thermal division of plates of secondary cementite or ledeburite cementite into separate microvolumes. The second alternative involves crushing of cementite crystals during deformation of the material and the formation of angular fragments. The third option is based on the conversion of metastable ledeburite cementite into stable carbides having prismatic morphology. It is shown that carbide heterogeneity in the unalloyed high-carbon steels such as damaskus is an aggregate of large faceted eutectic carbides with prismatic shape. It is expected that the formation of proeutectoid cementite with faceted prismatic form will have positive effect on the properties of cutting tool.

Damascus steel, bulat, Wootz steel, Indian steel