OS1217 すべり摩擦を受けた粒界形成と格子回転

Abstract

Sliding wear tests were performed on annealed iron plates of 99.99% purity, with a pin-on-disk type friction machine. After the wear tests, the iron plates were cut to investigate evolution of microstructure with electron backscatter diffraction (EBSD) method. In the vicinity of the worn surface, submicron grains with elongated shapes were generated. Below the submicron grain region, dominant grain boundaries were two kinds of low-angle grain boundaries which were parallel and inclined to surface. At deeper region from the worn surface, occurrence of continuous lattice was detected by EBSD analysis. In order to estimate local deformation mode, inclination of a preexisting boundary was measured. It was found that the lattice rotation angle was equal to the grain boundary inclination angle below the region where the parallel low-angle boundaries were formed. It is deduced from this result that shear deformation occurred along a plane vertical to the surface. Because being possibly formed by the rearrangement of edge dislocations gliding along this plane, the low-angle boundaries parallel to the surface is compatible with this shear deformation. At the upper part of the low-angle boundary region, the lattice rotation angle was no longer equal to the inclination angle. This should be because the shear deformation parallel to the surface became a dominant deformation mode instead.