Correlation Between the Mechanical Properties and Microstructure of Irradiated Iron and Low-Carbon Steel

The radiation hardening of iron and low-carbon steel was studied on the basis of transmission electron microscopy and tension test data. No visible defects were observed in the iron specimens after irradiation to 3.5×1019 n/cm2, E>1 MeV, at 35 C, as well as after postirradiation annealing at 150 C. Marked microstructural changes occurred in steel irradiated to 2.5×1018 n/cm2 both at 320 C and 450 C. In the former case a 5.1×109 cm-2 increase in dislocation density was found, while in the latter the presence of small dislocation loops of average diameter 200 Å and density 2.4×1014 cm-3 was observed. The approximative theoretical values of yield stress increment were calculated using the models for hardening by small dislocation loops and by a dislocation forest and were compared with the experimental values of the yield stress increment. A satisfactory agreement was obtained.