Microscopic plastic deformation behavior on free surface of copper during plane strain compression
Nosho Takayoshi; Shimizu Ichiro; Abe Takeji; Wakayama Masahiro; Tsutsumi Kenjiro
Abstract:The free surface of polycrystalline metal becomes roughened in metal forming process due to its microscopic inhomogeneity. In the present study, two dimensional surface roughness and three dimensional microscopic shapes of the roughened surface of pure copper caused by compressive plastic deformation under a plane strain condition were investigated, and the characteristics of the microscopic deformation behavior during plane strain compression were clarified in comparison with those during uniaxial compression. It was found that the surface roughness increased almost in proportion to the applied strain, but the roughness measured in the compressive direction was larger than that in the transverse direction. This is because the mountains which appear on the free surface during plane strain compression tend to elongate in the transverse direction. The primary wavelength of the surface shape was also obtained by means of the maximum entropy method. The primary wavelength in the transverse direction was almost twenty times of the average grain size, and it decreased in correspondence with the applied strain. This implies that the inhomogeneity of deformation behavior of copper appears under the scale of twenty grains in the transverse direction. Key Words:plasticity, plane strain compression, surface roughness, microscopic deformation behavior, polycrystalline copper