Study on grain deformation in bending zone of SUS304 stainless steel foil

In this paper, the grain deformation of SUS304 stainless steel foil under small fillet bending was studied. First, bending experiments were performed on 50 and 100μm thick foils, and the results showed that when the bending radius was close to the thickness of the foil, the surface grains in the bending zone collapsed and extruded, resulting in a rough surface. Then, Crystal Plastic Finite Element Method (CPFEM) was used to simulate the bending of different thickness foil (20, 50 and 100μm), in which the grains are hexagonal and the opposite edge distance is 20μm. Simulation results showed that when the relative fillet radius (the ratio of fillet radius to thickness) is similar, the surface layer of fillet becomes coarser with the increase of the foil thickness-grain size ratio. In addition, the uncoordinated intergranular deformation is caused by orientation difference, which leads to high density Geometric Necessary Dislocation (GND) in grain boundary region. Electron Backs-Scattered Diffraction (EBSD) experiments on recrystallized annealed foils with a thickness of 100μm showed that the GND density of the grain boundary after bending is significantly higher than that of the intragranular, which has the same distribution characteristics as the simulation results.