抄録
Stainless steel is mainly used as structural materials under severe environment. Therefor clarifying the fracture strength of stainless steel is important. The purpose of this study is to clarify the fracture toughness anisotropy of rolled stainless steel. Inclusion distribution is influenced by the rolling process. The stable crack grows by coalescence of voids which occur as nuclear inclusions. Therefore the distribution of inclusions affects the fracture strength of the material. In this study rolled SUS304 stainless steel with the thickness of 30mm was used. Specimens in the crack direction of the six were produced from this material. The fracture toughness values of these specimens were evaluated by direct current potential difference method. As a result, the fracture toughness of this material showed anisotropy. The specimen of which crack plane was parallel to the rolling plane showed lowest fracture toughness value. This tendency was the same as other the rolled metal material having ductile properties. As a result the orientation relationship between crack plane and rolled surface affects the fracture toughness. In addition, in case the large dimples are present in the fracture surface, the fracture toughness values of the specimens were low.
