Fig.6. Microstructures of different zones of 1# (a, d, g), 3# (b, e, h) and 5# (c, f, i) samples along the weld thickness direction: (a) SAZ, (b) top of NZ, (c) bottom of NZ, (d) top of TMAZ, (e) middle of TMAZ, (f) bottom of TMAZ, (g) top of HAZ, (h) middle of HAZ, (i) bottom of HAZ