Abstract
Sliding wear tests were conducted on Fe-20%Cr alloy single crystals having (001), (110) and (111) surfaces, using the ball-on-disk type friction machine under the condition of 10N vertical load and 30m wear distance. After the wear tests, the single crystals were cut to investigate microstructures developed below the worn surface. The cross-sectional observation revealed that subsurface regions of all the worn single crystals were composed of fine grains which were generated by severe plastic deformation introduced by the sliding wear process. It was confirmed from EBSD analyses that, below the fine-grained regions, all the single crystals rotated around the axis which is almost perpendicular to the wear direction. Such lattice rotation was expected to be a preceding event for the grain boundary formation in the fine-grained region. The lattice rotations were evaluated by the misorientation angles from the single crystal matrices. Extent of the lattice rotation depended on crystallographic orientation of the single crystals. The depth where the misorientation angle is 10° increased in ascending order of (001), (110) and (111) single crystals, suggesting that the lattice rotation was promoted favorably at the (111) single crystal. In order to understand the orientation dependence of the lattice rotation, we considered three slip deformation models (horizontal shear, vertical shear and resolved shear stress models) which incorporated the geometrical relationship between a slip system and wear direction.
