The crack initiation and the propagation during bending have been considered to be affected by second phase particles with micro-voids and shear-band. However, the effect of second phase particle distribution on formation of micro-voids, and the effect of micro-voids on crack initiation and propagation during bending have not been fully investigation. In this study, the effect of second phase particle distribution on formation of micro-voids, and the effect of micro-voids on crack initiation and propagation during bending were investigated by using the largest synchrotron radiation facility “SPring-8” and FE-SEM/EBSD. With increasing the bending ratio, micro-voids were increased around coarse particles nearby outer surface. In particular, coarse micro-voids were formed around coarse particles with high aspect ratio on shear-bands. At large cracking part, the coarse micro-void was observed at outmost layer section as crack initiation site, and coarse micro-voids and sheared fracture surface were observed at crack propagation site. At small cracking part with no propagation, Cube orientation grains were located under the small crack. It was considered that these cube orientation grains inhibited the formation of shear-bands, therefore propagation of cracks did not occur at small cracking area.
