June 30, 2004
Book Chapter

FURTHER MICROSTRUCTURAL EXAMINATIONS OF V-4Cr-4Ti PRESSURIZED CREEP TUBES

Abstract

Pressurized thermal creep tubes of V-4Cr-4Ti have been examined following testing in the range 650 to 800°C for tests lasting ~104 h. Creep deformation was found to be controlled by climb-controlled dislocation glide at all temperatures below 800°C whereas at 800°C, sub-grain boundary structure predominated and represented the main obstacle for dislocation motion. At 650 and 700°C after ~104 h an increased density of (Ti,V) oxy-carbo-nitride precipitates near the outer surface extending inwards a distance of 30 and 70 µm, respectively, was found. At 800°C, enhanced (Ti,V) oxy-carbo-nitride precipitation was observed across the entire tube wall thickness and may have affected creep response. Also, evidence for internal precipitation associated with the dislocation structure could be identified. The discussion section addresses differences in the controlling creep mechanisms between grain boundary sliding, sub-grain boundary controlled dislocation climb and individual dislocation climb processes.

Revised: May 18, 2007 | Published: June 30, 2004

Citation

Gelles D.S., and R.J. Kurtz. 2004. FURTHER MICROSTRUCTURAL EXAMINATIONS OF V-4Cr-4Ti PRESSURIZED CREEP TUBES. In Fusion Materials: Semiannual Progress Report for Period Ending June 30, 2004, edited by R. L. Klueh and Teresa Roe. 2-12. Washington, District Of Columbia:DOE Office of Fusion Energy Sciences. PNNL-SA-42949.