MECHANICAL-PROPERTIES OF LOW-ACTIVATION CR-MN AUSTENITIC STEELS CHANGES IN LIQUID LITHIUM

The mechanical properties of Fe-0.06C-12Cr-14Mn-4Ni-Al-Mo, Fe-0.10C-12Cr-20Mn-W, Fe-0.25C-12Cr-20Mn-2W, Fe-0.06C-17Cr-19Mn-3Ni-Nb-N, Fe-0.07-13Cr-20Mn-N steels attacked by liquid lithium were studied. Preexposure of steels was performed in static isothermal lithium at 723 and 873 K; in the hot leg of a convection loop at 723 K, and in inert atmosphere at 723 and 873 K for 2600 h. Lithium contained up to 400 ppm nitrogen and up to 1% hydrogen. The mechanical properties were deter-mined by tensile test in lithium and in vacuum at a strain rate of 1 X 10(-5)-1 X 10(-3) s-1. It was shown that mechanical properties of tested steels after exposure in the lithium changed more than for Cr-Ni steels. The strong embrittlement of steels containing nitrogen is associated with intergranular penetration of lithium. The character of other steels mechanical properties changes is difficult to explain and may be associated with nonmetallic impurities redistribution and steel phase composition changes. The main mechanical properties change took place continually for the first 1000 h at 723 K exposure. Noticeable change in the mechanical properties of the steels exposed to lithium at 873 K occured even until 2600 h of exposure. The effect of strength and ductility reduction through absorption did not occur.