Trial-manufacturing and evaluation tests on new material wrapper tube

Fujiwara, Masayuki*; Nishida, Toshio*; *; *

PNC TJ9058 89-003, 67 Pages, 1989/05

PNC-TJ9058-89-003.pdf:3.08MB

The high Cr ferritic/martensitic steels with a superior resistance to swelling are thought to be preferrable for the long-life wrapper tube materials of the large-scale FBR's. To evaluate the applicability of the ferritic/martensitic steels strengthened by solid-solution and carbide precipitation for the wrapper tubes, the material design to fullfil the requirements for the tensile and the impact properties, and the trial-manufacturing test were performed. The composition selected as a basis was 0.14C-0.5Ni-1Cr-0.5Mo-2.0W-0.25V-0.07Nb-0.06N, and the effects of N, V, and Nb contents and the heat-treatment conditions on the tensile and the impact properties were examined. (1)The tensile and yield strength at elevated-temperatures was largely affected by the heat-treatment conditions, while the effect of the chemical compositions on the strength was small. (2)The impact properties were largely affected by both chemical composition and the heat-treatment condition. The higher contents of N, V, and Nb than those of the basic composition increased the DBTT. (3)To fullfil the requirements for the tensile and the impact properties of the wrapper tubes, the basic composition selected in this study and the heat-treatment condition, normalized at 1050C and tempered at 710C, were thought to be suitable. (4)From the manufacturing test of the wrapper tubes applying the selected chemical composition and the heat-treatment condition, the wrapper tubes having high strength and superior impact properties exceed the requirements were obtained.