Reduction of irradiation-induced creep and swelling in AISI 316 by compositional modifications

Studies involving high fluence irradiations of compositionally modified AISI 316 stainless steel have demonstrated that the irradiation-induced creep and swelling of this alloy can be modified through a selective choice of alloying elements. Irradiation-induced swelling of specimens irradiated to fluences of 7 to 12 x 1022 n/cm2 (E > 0.1 MeV) is strongly influenced by the concentration of alpha-stabilizing elements such as Si and Mo. Relative minima and maxima in swelling vs composition diagrams are shown to exist. Irradiation-induced creep strain of AISI 316 is, in general, reduced by the same elements which reduce irradiation-induced swelling. It was found that the compositional dependence of swelling and creep in this alloy system can both be described through a description of the screening of dislocation strain fields. Compositional modifications which increase the mobility of the screening agents or allow the formation of more effective screening agents will decrease the swelling and irradiation creep. This screening results in a decrease in the interstitial-dislocation bias, which results in lower swelling and in reactor creep