The results of comparative investigations of variations in engineering and true characteristics of strength and ductility for austenitic stainless steel 12Crl8NilOTi, high-nickel alloy 03Cr20Ni45Mo4, and commercially pure molybdenum irradiated by neutrons in the WWR-K reactor core at a temperature lower than 370 K and the fluences ranging from 5.1022 to 2.1024 n/m2 (E>0.1MeV) are presented.
In tensile experiments at 293 K at the constant strain rate ~10-4 c-1 the curve showing variations in geometrical dimensions of specimens was recorded together with the strengthening diagram. This revealed regularities in deformation-induced change of specimen diameters measured at various cross-sections over the specimen operating length, and allowed us to determine true values of the yield strength and the failure stress, and to find the value of narrowing related to the start of the localized plastic deformation.
For steel specimens, true values of strains and stresses (with the specimen diameter and length variations taken in account), corresponding to onset of recording the martensite ferromagnetic phase, are determined. It has been shown that, under the present test conditions, true stresses of á-phase formation in deformed steel are found to decrease as the neutron fluence increases.