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Fujiwara, Masayuki*; Nishida, Toshio*; *; *
PNC TJ9058 89-003, 67 Pages, 1989/05
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 1050
C 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.
Fujiwara, Masayuki*; Nishida, Toshio*; *; Soshiroda, Tetsuo*
PNC TJ9058 88-009, 77 Pages, 1989/02
The Spray-Dispersion (SD) Method is a recently developed technique which can produce a steel containing dispersed oxide particles sprayed from outside into the molten steel stream. To evaluate the applicability of the oxide dispersion strengthened (ODS) ferritic steels made by this new process for the long life core materials of the large scale FBR's, a fundamental study using Fe-13Cr ferritic steels was conducted. The main results are summarized as follows : (1)From the results of the simulation tests utilizing water and molten Sn, it was cleared that the molten metal diameter, the throat diameter and the number of the spray gas nozzles, the spray gas nozzle angle, and the spray gas pressure are the important to get a favorable spray-dispersion condition. (2)An experimental apparatus for the SD method installed in a vacuum induction furnace was manufactured and the SD tests utilizing ZrO
oxide particles were performed on the 10kg ingots of Fe-13Cr ferritic steels containing the dispersion-controlled elements such as Ti, Nb, V. The maximum quantity of ZrO
added in the steels was about 0.5%. But the oxide particle sizes in the steels were large and the distribution of the oxide particles was not homogenious. It is considered that the higher pressure of the spray gas and the higher feed rate of the oxide powders are needed for the improvement of these problems.
Fujiwara, Masayuki*; Nishida, Toshio*; Soshiroda, Tetsuo*; *
PNC TJ9058 88-007, 189 Pages, 1988/08
As the Oxide Dispersion Strengthened (ODS) ferritic steels have excellent resistance to swelling as well as superior strength at elevated temperatures, they are expected for the long life fuel claddings of the large scale FBR's. To evaluate the applicability of the ODS ferritic steels for the fuel claddings, we investigated the effects of the manufacturing conditions, the additional elements (Nb, V, Zr), the combined strengthening of solutin (W,Mo) and dispersion hardenings, and the kinds of the oxide particles (YO
, ZrO) on the properties, especially the elevated - temperature strength, of the ODS ferritic steels. (1)The conditions of the mechanical alloying(MA) process using the attritor showed the strong effect on the properties of the ODS steels. The higher energy the alloy powders are given, the better dispersion of the oxide particles is obtained. The higher agitater speed of the attritor is thought to be the most efficient condition among the MA conditions. (2)The mixed oxied were formed in the Nb and Zr added steels, but in the V added steel the formation of the mixed oxides was not observed. The additions of Nb and V raised the elevated - temperature strength, while the addition of Zr showed little effect on the strength. (3)The additions of the solution hardening elements, Mo and W, up to about 2% increased the creep rupture strength. The effect of W was larger than that of Mo. (4)We chose ZrO instead of YO, and studied the effect of ZrO dispersion on the elevated - temperature strength of the ODS ferritic steels. Although the effect of ZrO on the strength is rather smaller than that of YO, the dispersion strengthening by ZrO particles was observed.
-Ray Irradiation Effects on Corrosion Resistance of Alloys for Storage of High-Level Waste Packages(I)*; ; ; Araki, Kunio; *; *; *
JAERI-M 82-061, 28 Pages, 1982/07
no abstracts in English
