Specimen size effects on fracture toughness of JLF-1 reduced-activation ferritic steel

Four different sizes of compact tension (CT) specimens of a reduced activation ferritic steel, JLF-1 steel, were fabricated and the fracture toughness was measured at room temperature by means of the unloading compliance method referring to in the ASTM E1820-99a. The <f>JQ</f> values obtained for the 1T–1CT and 1/2T–1CT specimens were 404 and 623 kJ/m2, respectively, indicating that the <f>JQ</f> value increased with decreasing the specimen thickness. On the other hand, the <f>JQ</f> value decreased when specimens were miniaturized while maintaining the similar proportions. The <f>JQ</f> values for the 1/2CT and 1/4CT specimens were 371 and 321 kJ/m2, respectively. Specimen size effects are interpreted in terms of an increase in the plain stress state region and plastic zone size at the crack tip in the specimen. [Copyright &y& Elsevier]