Fig. 5 OM image of FSW joint on cross section
The detail statistical information of grain structure of BM, WNZ and
softening band in AS-HAZ were further investigated by EBSD. The detailed
statistical fractions of recrystallized, sub-structured, deformed
structure were calculated and listed in the corresponding figures.
According to the EBSD maps shown in Fig. 6, it can be found that BM and
AS-HAZ mainly consisted of grains elongated along the rolling direction,
many sub-grains inside grains as
well as some small recrystallized grains in grain boundaries were
distinguishable (Fig. 6a and 6c). In WNZ, the grain size dramatically
decreased and the intragranular sub-grains entirely vanished (Fig. 6e),
presenting a complete recrystallized equiaxed-grained structure (Fig.
6f).