Fracture toughness determination of a nuclear pressure vessel steel by instrumented Charpy impact test

Charpy V-notch (CVN) impact testing is widely used to characterise the resistance of a material, by measuring the energy consumed by a specimen during the impact. Notably, materials undergoing a ductile-to-brittle transition, e.g. ferritic steels, are quality controlled by means of CVN testing, and their ductile-to-brittle transition temperature can be determined. Charpy testing is also widely used in the toughness assessment of large forged components, e.g. pressure vessels for pressurised water reactor (PWR). However, to justify the integrity of components, a fracture toughness versus temperature curve is needed and no satisfactory link exists between the Charpy impact energy and the fracture toughness. A study has been engaged in order to establish a non-empirical relationship between the Charpy impact energy and the fracture toughness of a A508 Cl. 3 steel. The methodology is based on the local approach of fracture. (authors)