Some Issues by Using the Master Curve Concept

The master curve concept allows to determine limit curves of fracture toughness for defined failure probabilities and a reference temperatures based on it. Thus fracture mechanical values can be supplied for the stress analysis. This paper presents the application of the master curve concept for the determination of the reference temperature over the thickness of a plate of RPV steel. It was shown that the master curve concept is applicable for the fracture mechanical characterisation of material in different conditions using small test specimens. A special problem with the use small specimens is the definition of the test temperature, at which fracture toughness values can be determined within the validity limits. It became clear that the criteria for definition the test temperature and the minimum number of specimens indicated in the ASTM E1921-97 standard are applicable and sufficient respectively only for homogeneous materials.