EFFECTS OF MINOR ALLOYING ELEMENTS UPON SWELLING AND IN-PILE CREEP INMODEL PLAIN FE-15CR-15NI STAINLESS-STEELS AND IN COMMERCIAL DIN 1.4970 ALLOYS

A pressurized tube experiment was carried out to determine swelling an d in-pile creep of a series of model plain Fe-15Cr-15Ni stainless stee ls and of different heats of the commercial German steel DIN 1.4970. S pecial attention was paid to the influence of minor alloying elements. Addition of Si most effectively suppresses swelling while variation o f the Ti content results in a complex behaviour with the maximum suppr ession of swelling obtained for a Ti concentration somewhere near 0.25 %. This results from a complex interaction between C and Ti. Consequen tly, a good swell resistance is achieved for DIN 1.4970 through a high Si content and understabilization. Good qualitative agreement has bee n found between the results of simulation and neutron irradiations; th is does not apply to variations of major components like Cr and Ni. Th e intercorrelation between swelling and in-pile creep has been confirm ed up to 90 dpa and can be described by an equation consisting of a SI PA term and an intercorrelation term. The discrepancy in the stress ex ponent of the intercorrelation term is still unsolved since the data a nalysis implies an exponent of 3/2, while theory and a formerly determ ined correlation both suggest a value of 1.