HARDNESS OF 12CR-8MO FERRITIC STEELS IRRADIATED BY NI IONS

12Cr-8Mo and 12Cr-8Mo-0.1Y(2)O(3) ferritic steels were irradiated with 4-MeV Ni3+ ions up to 300 dpa at 525 degrees C. Microstructural evolu tion was examined by transmission electron microscopy (TEM) and mechan ical properties were evaluated with a depth-sensing ultra-low load ind entation hardness tester at room temperature with a maximum load of 1 gf. Effects of aging at 650 degrees C for 115 h and heat treatment at 525 degrees C for 50 h were also investigated. TEM observations reveal that these steels exhibit no void swelling in the present irradiation condition. Aging and heat treatment induces precipitation of Laves ph ase and ion-irradiation enhances precipitation. The induction and enha ncement of precipitation strengthened the specimens.