Effect of neutron irradiation on tensile properties of materials for pressure vessel internals of WWER type reactors

Tensile properties of austenitic stainless steels used for pressure vessel internals of WWER type reactors (18Cr–10Ni–Ti steel and its weld metal) in the initial and irradiated conditions were investigated. Based on the presented original investigations and generalization of the available experimental data the dependences of yield strength and ultimate strength on a neutron damage dose up to 108 dpa, irradiation temperature range 320–450 °С and test temperature range 20–450 °С were obtained. The method of determination of the stress–strain curve parameters was proposed which does not require uniform elongation of a specimen as an input parameter. The dependences was proposed allowing one to calculate the stress–strain curve parameters for 18Cr–10Ni–Ti steel and its weld metal for different test temperatures, different irradiation temperatures and doses. The dependences were obtained to describe the fracture strain decrease under irradiation at a temperature range 320–340 °С when irradiation swelling is absent.