Unraveling the formation mechanism of deformation bands in AA1100 alloy during plane forging and return-plane forging

•The formation mechanism of DBs observed in AA1100 after PF and R-PF during MADF was unraveled by microtexture analysis.•Calculation of the lattice rotation rate and the divg˙ was used to evaluate the kinematic stability of deformed grains under the R-PF.•The heterogeneity of the orientation stability was used to explain the development of the DBs in the R-PF specimen.•CPFEM successfully simulated the development of DBs within deformed grains during the R-PF.•The heterogeneity of orientation stability occurring within the blurry bands enhanced the formation of DBs in the deformed grains during the R-PF.