Page 39 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 315

distribution with the decrease of compression
in the initial layers in relation to the blasted
surface. With the use of scanning electron
microscopy, the region affected by grit blasting
was observed, noting that the plastically de-
formed regions are located in the same regions
where the compressive residual stress decrease.

The profile obtained by X-ray diffraction pro-
vides necessary information with the aim
of combining the effects of microstress (mi-
crostrain) on macrostress (residual stress). This
relationship was confirmed by the overlap of
the results found in the distribution of the
microstrain of the crystalline lattice with the
residual stress along the thickness in the plas-
tically deformed region.

The results of the x-ray diffraction tests show
an existence of tensile anisotropy between
the planes generated by stacking faults and
the dislocations density. Therefore, to obtain
the values of the microstress, the factors of
the elastic constants and the crystallographic
planes must be considered. The method ap-
plied was the modified Williamson-Hall.

In addition, the study of the distribution of the
mean crystallite size along the thickness of the
X-ray diffraction profile was provided and the
results showed that this distribution varies
inversely with microstrain. The relationship
between the mean crystallite size and the
variation of the interplanar distances corre-
sponds directly to changes in the densities of
dislocations occurring in the material, which
in turn are linked to the microstrain of the
crystalline lattice.