220
S. S. Nayak et al.
have been taken as DRXed grains. Results showed that the highest fraction of DRXed
grains is at SZ than in other regions. This is due to larger material deformation at the
SZ generating a high density of dislocations. This provided an intense driving force
for DRX and grain growth at SZ.
As discussed above, there was an existence of inhomogeneous microstructure
along the weld cross section. This is due to the different degrees of frictional heat and
plastic deformation in the weld cross section. Materials at SZ are mechanically stirred
from AS to the trailing edge of the tool. TMAZ and HAZ are subjected to low plastic
deformation, but are primarily affected by the heat. This causes different orientations
of grains in the polycrystalline materials and anisotropic mechanical properties in the
weld regions. Anisotropy is dependent on the crystallographic texture components
of weld regions. EBSD ODF maps on the plane comprising of ND and TD are shown
in Fig. 6.13, and it can be noticed that texture components of base aluminium were
changed in the weld regions.
Referring to Fig. 6.13a, BM was dominated with Cube RD {013} <100> , Rotatedcube {001} <110> and Goss {011} <001> which are recrystallized and deformed
textures, respectively. HAZ was dominated of recrystallized type texture component
which includes Cube {001} <100> , whereas the TMAZ was dominated with Cube
RD {013} <100> and Brass {011} <211> which are recrystallized and deformed
texture component, respectively (Fig. 6.13b, c). The effect of frictional heating and
material deformation at TMAZ produced both recrystallized and deformed textures
whereas the effect of only frictional heating at HAZ led to the formation of recrystallized textured grains. The SZ was dominated with Goss {011} <100> , E {111} <110>
and F {111} <112> textured grains which are known as deformed and shear textures
(Fig. 6.13d). Material at SZ was extruded and sheared under the effect of the tool
which is the likely explanation for shear and deformed textured grains. The texture
components, their levels of intensity and the types obtained from ODF map are given
in Table 6.1. It can be noticed that FSW reduced the texture intensity in the weld
regions as compared to the base aluminium. In addition, FSW transformed recrystallized and deformed textured grains of BM to shear and deformation textured grains at
the SZ. TMAZ has similar texture grains as base AA6061-T6 whereas HAZ has only
recrystallized texture grains. It can be seen that various types of texture components
have been found depending on the weld zones. Texture components, such as Cube
{001} <100> , Rotated-cube texture {013} <100> and Goss texture {011} <100>
components are known as recrystallized texture, whereas texture components such
as Brass {011} <211> , Cu {112} <111> and S {123} <634> are known as deformed
textures.
HAZ has both deformed and recrystallized texture components, whereas TMAZ
and SZ have only recrystallized texture components. This is due to the synergetic
effect of frictional heat and deformation at SZ and TMAZ, whereas HAZ was affected
by the frictional heat only.
The major texture components in the FSW for aluminium are {110} <110> and
{114} <221> , which are shear texture components with respect to the local reference
plane. Further, the post-weld study of the FSW of aluminium revealed the presence of
an alternate shear texture components of B/B and C in the weld SZ region. Similar
S. S. Nayak et al.
have been taken as DRXed grains. Results showed that the highest fraction of DRXed
grains is at SZ than in other regions. This is due to larger material deformation at the
SZ generating a high density of dislocations. This provided an intense driving force
for DRX and grain growth at SZ.
As discussed above, there was an existence of inhomogeneous microstructure
along the weld cross section. This is due to the different degrees of frictional heat and
plastic deformation in the weld cross section. Materials at SZ are mechanically stirred
from AS to the trailing edge of the tool. TMAZ and HAZ are subjected to low plastic
deformation, but are primarily affected by the heat. This causes different orientations
of grains in the polycrystalline materials and anisotropic mechanical properties in the
weld regions. Anisotropy is dependent on the crystallographic texture components
of weld regions. EBSD ODF maps on the plane comprising of ND and TD are shown
in Fig. 6.13, and it can be noticed that texture components of base aluminium were
changed in the weld regions.
Referring to Fig. 6.13a, BM was dominated with Cube RD {013} <100> , Rotatedcube {001} <110> and Goss {011} <001> which are recrystallized and deformed
textures, respectively. HAZ was dominated of recrystallized type texture component
which includes Cube {001} <100> , whereas the TMAZ was dominated with Cube
RD {013} <100> and Brass {011} <211> which are recrystallized and deformed
texture component, respectively (Fig. 6.13b, c). The effect of frictional heating and
material deformation at TMAZ produced both recrystallized and deformed textures
whereas the effect of only frictional heating at HAZ led to the formation of recrystallized textured grains. The SZ was dominated with Goss {011} <100> , E {111} <110>
and F {111} <112> textured grains which are known as deformed and shear textures
(Fig. 6.13d). Material at SZ was extruded and sheared under the effect of the tool
which is the likely explanation for shear and deformed textured grains. The texture
components, their levels of intensity and the types obtained from ODF map are given
in Table 6.1. It can be noticed that FSW reduced the texture intensity in the weld
regions as compared to the base aluminium. In addition, FSW transformed recrystallized and deformed textured grains of BM to shear and deformation textured grains at
the SZ. TMAZ has similar texture grains as base AA6061-T6 whereas HAZ has only
recrystallized texture grains. It can be seen that various types of texture components
have been found depending on the weld zones. Texture components, such as Cube
{001} <100> , Rotated-cube texture {013} <100> and Goss texture {011} <100>
components are known as recrystallized texture, whereas texture components such
as Brass {011} <211> , Cu {112} <111> and S {123} <634> are known as deformed
textures.
HAZ has both deformed and recrystallized texture components, whereas TMAZ
and SZ have only recrystallized texture components. This is due to the synergetic
effect of frictional heat and deformation at SZ and TMAZ, whereas HAZ was affected
by the frictional heat only.
The major texture components in the FSW for aluminium are {110} <110> and
{114} <221> , which are shear texture components with respect to the local reference
plane. Further, the post-weld study of the FSW of aluminium revealed the presence of
an alternate shear texture components of B/B and C in the weld SZ region. Similar