Mechanical properties of primary circuit materials of the WWER-440 nuclear power plants

An overview is given of the mechanical properties of primary circuit austenitic materials of four WWER-440 NPPs. For the fracture test of austenitic pipes, 30 specimens from the base material and 44 from the weld metal were analyzed. The data set covered both longitudinal and circumferential orientation of crack extension and a temperature range from 24 to 300 degC. Tensile results were taken into account without considering orientation. Fracture properties are relevant to circumferential crack propagation. The fracture results lead to the conclusion that ageing possibly plays a role in case of the duplex austenitic weld metal. The Czech material manufactured at the Vitkovice steel works is compared with Russian steels characterized by lower yield stress and higher fracture resistance. (Z.S.) 1 tab., 7 figs., 4 refs