Abstract
Rolled metallic materials have anisotropy of mechanical properties due to the shape of the crystal grain. We have carried out experimental studies focusing on the fracture strength anisotropy of rolled metallic materials. This paper reported anisotropy of fracture toughness of two kinds of rolled steels (SM490A and SS400). SM490A steel shows a property of ductile fracture in the fracture toughness test. On the other hand, SS400 shows a property of brittle fracture. Six kinds of different compact tension specimens of the crack plane orientation were made by these materials. The fracture toughness tests were carried out by these specimens and the fracture toughness values were evaluated. As a result SM490A showed anisotropy clearly. In addition, the fracture surface was different in each direction. The direction relations of rolled plane and crack plane influenced a fracture toughness value. SS400 showed anisotropy, but the tendency was different from that of SM490A. The anisotropy of this material cannot be explained by the relation of two planes.
