抄録
Rolled or drawing metallic materials have anisotropy of mechanical properties because of the orientation of crystal grains. Fracture toughness values of these materials also have anisotropy due to the reason. The anisotropy of fracture toughness of the rolled metallic materials has been researched experimentally in our laboratory. The fact that the rolled metallic materials have strong anisotropy of fracture toughness became clear. The relations of rolling plane and crack plane have an influence on the fracture toughness values. The shapes or distributions of crystal grains of rolled metallic materials become plane-symmetrical. On the other hand, these of drawing metallic materials become axis-symmetrical. The purpose of this study is to make clear the anisotropy of the fracture toughness of the drawing metallic. Chromium-molybdenum steel (SCM435) round bar was used for this study. The specimens of six kinds of directions were processed in this material. The fracture toughness tests were carried out by the difference potential method. According to the tests, the fracture toughness anisotropy of this material was not remarkable as rolled materials.
