IRRADIATION CREEP STUDIES OF TITANIUM-ALLOYS

Stress relaxation measurements were performed on four titanium alloys, Ti-6Al-4V (in three heat treat conditions), Ti-6242S, Ti-5621S and Ti-15-333. The specimens were thin rectangular beams elastically bent in uniform radii of curvature and irradiated to a fluence of 4 × 1021n/cm2 (E > 0.1 MeV) at about 450°C in EBR-II. Postirradiation measurements of the residual curvature of the specimens indicated the amounts of irradiation creep that had occurred. Although further experimental work is required to separate primary and steady state creep components, the data provided a good comparison between the alloys and with stainless steels irradiated in similar tests. Among the titanium alloys irradiated, the superalpha alloys Ti-5621S and Ti-6242S had the greatest creep strengths, about equal to CW 316 SS. The beta alloy Ti-15-333 and Ti-6Al-4V in the duplex annealed condition were weakest. TEM and optical metallography were performed on the post-irradiation microstructure of some alloys. Beta platelets and linear precipitate arrays were observed in the mill anneal and duplex anneal conditions of Ti-6-4. An ordered phase α2 also was found in the duplex structure. © 1979.