Fig. 12 Growth process of dislocations on the interface when d3
is applied along the y -axis. The whole process is contained in
the first quarter of the first cycle. (a) timestep=11.2ps, d=9.766Å. (b)
timestep=12.0ps, d=10.172Å. (c) timestep =12.8ps, d=10.522Å. (d)
timestep =13.6ps, d=10.816Å. Green and blue lines in bcc-Fe matrix
correspond to 1/2<111> and
<110> dislocations, respectively. (e) Viewing
area and orient of the dislocation growth. The view is kept parallel to
the interface by rotating the coordinate system.
Severe shear deformation leads to excessive growth of dislocations which
evolve into surface defects such as stacking fault, and the interlaced
dislocations ultimately result in irreversible plastic accumulation.
Note that the nucleation of dislocations usually occurs on the interface
between bcc-Fe and cementite. Therefore, it is convincing that the
generation and accumulation of dislocations on the two-phase interface
or the boundary of carbide inclusions are the origin of the cyclic
plastic accumulation. This may also be the main reason why bearing
steels damage usually appears near inclusions such as carbides.