Verification of plastic strain values during ovalization of a ring specimen from a fuel element shell of a fast neutron reactor

Mechanical testing of ring specimens for radial compression between flat dies (ovalization) was carried out, supplemented by analyzing the stress-strain state calculated by a specialized computer program. To verify the values of plastic strain, laser marks were made on the side surface of the ring. It is found that the maximum plastic deformation accumulates at the inner and outer walls of the ring, where maximum tensile and compressive stresses act, respectively. The deviation of the experimental values of plastic strain from the predicted ones does not exceed 10%. It is shown that the analysis of the stress-strain state of the ring specimen during ovalization can be useful for evaluating the critical values of the mechanical characteristics of the shell material irradiated in a fast neutron reactor to a high damaging dose.