EBSD analysis of graphitized steel microstructure after compression deformation at room temperature

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The graphitized steel has attracted considerable attention due to its excellent cutability and good properties at cold forming. Compression deformation at room temperature of graphitized steel (0.43 % C) with a ferrite-graphite microstructure was performed on a universal testing machine. Microstructures of deformed samples were studied using the analysis technique of Electron Back-Scattered Diffraction (EBSD). The evolution of microstructure morphology, texture, distribution of Kernel Average Misorintations (KAM) and the Taylor factor in the zone of large deformations of deformed samples with different degrees of deformation is discussed. The results show that the studied steel has a good ability to compression deformation. During compression deformation, with an increase in deformation degree the deformation morphology of the ferrite grain and graphite inclusions gradually stretch in the direction perpendicular to the compression axis and they are represented as fibrous forms. The orientation of ferrite grains in the matrix is gradually obvious, and the orientation of ferrite grains around graphite inclusions is not obvious, that is, the number of grains oriented to <100>, <111> in the matrix is much greater than around graphite inclusion. In addition, KAM and the Taylor factor in the large deformations region of compression samples show that the deformation degree of ferrite grains around graphite inclusions is less than that of ferrite grains in the matrix. The reason for this is that the soft graphite inclusions can reduce the degree of dislocation pile-up.