Improved evaluation of ring tensile test ductility applied to neutron irradiated 42XNM tubes in the temperature range of (500–1100)°C

Abstract Chromium-nickel alloy 42XHM is considered as a promising material for future generations of nuclear reactors, primarily as a material for the fuel elements shells in the development of accident tolerant fuel. However, as with most nickel-based alloys, 42ХНМ is characterized by a sharp decrease in plastic properties in the temperature range of (500–900)°C. This effect is enhanced by neutron irradiation. Preliminary tests of ring samples of 42XNM alloy (after irradiation as a part of the VVER-1000 control system) in the temperature range of ductility failure showed that the standard technique for processing tensile diagrams does not allow to evaluate the plastic properties correctly at low strains. Therefore, in this work, the alternative method for testing ring samples from materials with low plastic characteristics was developed. It was shown that the minimum value of the permanent strain of the irradiated 42XHM alloy in the temperature range of (500–1100)°C, determined by the alternative method, was ∼1.6% at 750 °C.