Evolution of cementite structure in carbon steel. 1. Diffraction data

Methods of X-ray diffraction analysis and transmission electron microscopy with microdiffraction were used to investigate cementite structure in high carbon steels U8 and U15 heat treated under various conditions. It is revealed that diffraction spectra regularly display the reflexes incompatible with the space group Pnma. The latter is commonly related to atomic crystal structure of cementite. The structure of cementite is assumed to have to be described by an alternative space group with lower symmetry