Formation of Faceted Excess Carbides in Damascus Steels Ledeburite Class

Abstract

In this research was developed stages of formation troostite-carbide structure into pure Damascus steel ledeburite class type BU22А obtained by vacuum melting. In the first stage of the technological process, continuous carbides sheath was formed along the boundaries of austenitic grains, which morphologically resembles the inclusion of ledeburite. In the second stage of the process, there is a seal and faceted large carbide formations of eutectic type. In the third stage of the technological process, troostite matrix is formed with a faceted eutectic carbide non-uniformly distributed in the direction of the deformation with size from 5.0 μm to 20 μm. It found that the stoichiometric composition of faceted eutectic carbides is in the range of 34 < C < 36 (atom %), which corresponds to -carbide type Fe2C with hexagonal close-packed lattice. Considering stages of transformation of metastable ledeburite in the faceted eutectic -carbides type Fe2C, it revealed that the duration of isothermal exposure during heating to the eutectic temperature, is an integral part of the process of formation of new excess carbides type Fe2C with a hexagonal close-packed lattice. It is shown that troostite-carbide structure Damascus steel ledeburite class (BU22А), with volume fraction of excess -carbide more than 20%, is fully consistent with the highest grades of Indian steels type Wootz. Modern Damascus steel type BU22А (Russia) can be described as carbon steel ledeburite class, with similar structural and morphological characteristics of die steel type X12 (Russia) or Cr12 (China) and high-speed steel type P6M5 (Russia) or W6Mo5Cr4V2 (China), differing from them only in the nature of excess carbide phase.