A constitutive expression for the twinning stress in BCC metals is developed using dislocation emission from a source and the formation of pile-ups, as rate-controlling mechanism.
The annihilation of dislocations at free surface leads to recovery of machined surface, accompanied with formation of surface pile up [38].
It is known that the work piece material is displaced by the cutting tool in terms of formation of surface pile up around the cutting route and formation of chip in the front of the cutting tool rake face.
A qualitative model for the formation of dislocation pile-ups is proposed.
It is shown that solid solution hydrogen favours planar slip and the formation of dislocation pile-ups.
The embedded nanoscale structure originates from the formation of the pile-up, which is determined by the elastic-plastic property of materials.
The formation of dislocation pile-ups and related small-angle subgrain boundaries in block-cast multicrystalline silicon for photovoltaic applications has been studied by means of white-beam X-ray topography (WB-XRT).
This indicates that as the grain size drops below the grain boundary strengthening limit, a smaller grain size would suppress the formation of dislocation pile-ups and instead promotes more grain boundary diffusion and sliding, which resolves the applied stress and in turn reduces the material's yield strength.
They support the successive steps of the corrosion enhanced plasticity model, which is based on a local softening in the SCC crack region and on the repeated formation of a dislocation pile-up at some distance ahead of the crack.
If this condition is not satisfied, the grain boundary will activate an alternative mechanism to relieve the strain accumulated from accommodation of lattice dislocations and the stress concentration associated with the formation of a dislocation pile-up.
The investigation revealed strong temporal (dry period vs. recharge period), and spatial (slope vs. central region of pile) variability in the formation of acid mine drainage.
