Microalloying steels with small quantities of boron and rare-earth elements improves the radiation-swelling resistance of austenitic stainless steels. Investigations have been carried out on 0.08C-16Cr-15Ni-3Mo-Nb steel with additions of 0.005 to 0.016 mass% of boron, 0.05% of rare-earth metals (REM), and 0.01% of yttrium in the annealed condition after irradiation at temperatures from 380 to 650°C within the damage dose range 33 to 78 dpa. The results indicate a decrease of swelling with increase of the total content of boron, REM, and yttrium microadditions; in this case, the period preceding steady void growth increases. The microstructural changes in the steel with different microadditions do not exhibit significant differences. The same microstructural states in different types of steel are obtained at different damage doses but with the same swelling.
The curves of mechanical properties characteristics plotted as a function of swelling for different types of steels are in good agreement with one another. First, this means that the swelling value can be used as a measure of the development of the mechanical properties degradation process; second, this allows the prediction of the mechanical properties of steel after microalloying with boron, REM, and yttrium from the results of investigations of these steels without these additions.