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JAEA Reports

Characteristics and experimental evaluation of super-heat-resisting Nb-based and Mo-based Alloys

Morinaga, Masahiko*; *; *; *

PNC TJ9603 97-001, 95 Pages, 1997/03

[PURPOSE] Nb-based and Mo-basd alloys have been investigated in order to develop the frontiers of matelials technique which will be utililized in the environment of high-temperature liquid alkali metals. In this study, both mechanical properties and corrosion resistance to liquid Li were evaluated for two designed Mo-based alloys, Mo-15Re-0.1Zr and Mo-15Re-0.1Zr-0.1Ti. In addition, a series of corrosion test was performed with provisionally designed Nb-based alloys, Nb-(1-4)Hf. [EXPERIMENTAL METHODS] (1)High-temperature tensile test : A tensile test in the Ar atmosphere was carried out at 1473K for the designed Mo-based alloys. Commercial TZM alloy was also tested as a reference. (2)High-temperature creep test : A Creep test in the Ar atmosphere was performed at 1473K under the several applied stress levels for the designed Mo-based alloys. (3)Workability test : A three-point bend test was carried out at room temperature to evaluate the workability of the designed Mo-based alloys. (4)Corrosion resistance to liquid Li : Both the provisionally desingned Nb-based alloys and the designed Mo-based alloys were immersed in the liquid Li at 1473K. The weight change was measured as an indication of the corrosion resistance. Also, the Auger electron spectroscopy analysis was performed with several specimens to examine the surface state of them after corrosion tests. [RESULTS AND DISCUSSIONS] (1)High-temperature tensile properties : The designed Mo-based alloys were superior in the tensile properties at 1473K to the commercial TZM alloy. In fact, both the tensile and yield strengths of them were about 1.5 and 2.3 times higher than the TZM alloy, respectively. (2)High-temperature creep properties : The creep rate of the designed Mo-based alloys at 1473K was lower, compared to other solid solution hardening Mo-based alloys, but higher than the precipitation hardening TZM alloy. (3)Workability : The workability of the designed Mo-based alloys was satisfactory regardless ...

JAEA Reports

High-temperature strength test of the liner material (II); High-temperature tensile and creep property of SM400B welded joint material

; Aoto, Kazumi;

PNC TN9450 97-012, 75 Pages, 1996/11

PNC-TN9450-97-012.pdf:25.58MB

This report described the results of tensile and creep tests under a high temperature with the welded joints of liner plate (SM400B) used in SHTS cells of leaked sodium storage system of "NONJU plant". Results obtained are summarized as follows. (1)Foundmental high temperature strength characteristics data of the welded Joints were acquired. (2)There is no effect of heat treatment and cut-out direction on tensile strength and rupture elongation of liner plate. (3)The rupture ductility (rupture elongation and reduction of area) is lower than one of the base metal. Especially, rapidly droped in the temperature over 800 $^{circ}$ C. (4)The creep strength of welded joint is almost same as one of the based metal. It will be estimated the effect of change of the micro-structure on the ductility. (5)Generally speaking, two phases of phase and phase intermingled exist under about 800 $^{circ}$ C, and phases transform to the phase under about 900 $^{circ}$ C over Ac3 transformation point. Then the grain boundary in HAZ, begin to grow, and the intergranular failure appears in over 900 $^{circ}$ C. The results will be applied to evaluate the stractural integrity of SHTS cells of leaked sodium storage system of "MONJU plant". (SHTS ; Secondary Heat Transfer System)

JAEA Reports

Investigation of creep behavior analysis of a coiI spring

Tsukimori, Kazuyuki

PNC TN9410 95-203, 17 Pages, 1995/08

PNC-TN9410-95-203.pdf:0.53MB

A mechanical hold down method is under discussion as the means to prevent fuel assemblies from being lifted up in the scope of investigation of the recycle reactor conception at Plant Engineering Section. The device of the mechanical hold down system is a coil spring. In this case it is necessary to maintain enough pressure force in high temperature region. Therefore, it is needed to analize creep behaviors of coil springs. At this stage it is desirable to survay parametrically the creep behaviors of various dimensions of coil springs rather than to analize detailed behaviors by FEM. This paper describes the investigation of a creep behavior analysis method of coil springs. In the development process of the method the torque of the spring is derived from the assumption of shear stress field and hear distribution of shear strain in the radius direction and the constitutive equation of creep, and finally the spring force can be obtained by the equilibrium equation as the function of time. For implementation of this method a simple program should be created since the shear stress distribution in the radius direction is nonlinear, however, a wide ranged parametric survay can be done on the creep behavior of coil springs of arbitrary shape, dimension and material.

JAEA Reports

Mechanical properties on high Cr-Mo steels at elevated temperature (V); Tensile, creep and relaxation properties of Mod.9Cr-1Mo steel plate and tube for steam generator.

; *; ; Yoshida, Eiichi;

PNC TN9410 94-261, 143 Pages, 1994/06

PNC-TN9410-94-261.pdf:2.54MB

In this study, tensile, creep and relaxation test in air were performed in order to examine the mechanical properties of Mod.9Cr-1Mo steel which is a candidate material for once throuth type steam generator of large scale fast breeder reactor. Tested materials were plate(12mmt) simulating heat exchenger tube and heat exchenger tube of Mod.9Cr-1Mo steel and 9Cr-2Mo steel was also tested as reference material. Results obtained are summarized as follows. (1)Tensile properties (a)Ultimate tensile strength and 0.2% yield strength of Mod.9Cr-1Mo steels were higher than the tentative Su and Sy values of the design allowable stress in the test temperature below 600 $^{circ}$ C. (b)Ultimate tensile strength of Mod.9Cr-1Mo steels plate and tube were higher than that of 9Cr-2Mo Steels. (3)The difference in ultimate tensile strength and 0.2% yield strength between steel plate and tube could not be found in these tests. (2)Creep properties (a)Creep rupture strength of Mod.9Cr-1Mo steel plate and tube was higher than the tentative S $_{R}$ value of the design creep-rupture stress intensity at 500600 $^{circ}$ C, and this tendency is significant in the range of longer rupture time. (b)For the relation between steady creep rate and creep rupture time, steady creep rates obtained in this study coincided well with the $_{m}$ of tentative creep strain equation. (c)Creep rupture strength of Mod.9Cr-1Mo steel plate and tube was higher than that of 9Cr-2Mo steel. (3)Relaxation properties (a)In the strain range of 0.10.5%, stress rapidly relaxed during the short hold time, and stress relaxation tended to be saturate beyond 50hours. These relaxation stresses became large in higher temperature and higher strain level. (b)Stress relaxation behavior was predicted approximately by tentative creep equation of Mod.9Cr-1Mo steel. The analysis of these test results is continued to develop of evaluation method of material strength.