Abstract
In this paper, experimental results for anisotropy of the fracture toughness for the rolled steel are discussed. A rolled steel (SM490A) with thiclmess of 70mm was used in this experiment. Six kind of compact tension specimens were processed from this material for fracture toughness test. Each specimen has different crack plane orientations. The fracture toughness tests were carried out by these specimens. From these tests, anisotropy of the fracture toughness was confirmed. The fracture toughness values depended on the crack plane orientations of the specimens. When the crack plane was parallel to the rolled surface, the specimen showed the minimum fracture toughness value. On the other hand, the specimen of which crack plane was normal to the rolled surface showed high fracture toughness value. The anisotropy of fracture toughness can be explained by distribution of inclusions contained in the rolled steel.
