S.C Liu(Research Institute for Fracture Technology Faculty of Engineering
,
Tohoku University
,
Sendai
,
Japan
,
on leave from Dalian Railway Institute
,
Dalian 116028
,
China)II-Hyun Kown
,
T Hashida and H Takahashi(Research Institute for nacture Technology
,
Faculty of Engineering
,
Tohoku Univeristy
,
Sendai
,
Japan)
金属学报(英文版)
In order to evaluate the tendency of mechanical properties degrudation due to weld-ing and other processing in materials used for supporting coils in super conducting rnaguets utilized in thermonuclear jusion reactore, a small punch (SP) test was used.This test, which was originally developed to study irradiation damage using miniatursized specimens was performed at 77 and 4 K for solution treated and sensitized JN1 austenitic stainless steel, a candidate cryogenic structural material. The area under the load-deflection curve up to the maximum applied load in SP test was defined as the SP enerpy, to characterize the resistance to fracture. Although solution treated material exhibited ductile fracture mode with high SP enerpy, embrittlement behavior due to sensitization at 650-800°for 1-5 h was shown clearlg by SP test with brittle intergranular fracture and decreased SP enerpy. Comparison of the results obtained by SP test with those by fracture toughness test showed the usefulness of SP test for evaluation of sensitization induced embrittlement at cryogenic temperature. The re-sults obtained in this study can be very usefol in predicting the degradation due to welding and other processing in cryogenic materials.
关键词:
small punch test
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null
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null
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L.F. Zhang
,
K.K. Cai
,
Y. Qu and Y.S. Shen Postdoctoral Fellow of Japan Science Promotion Society Taniguchi Lab.
,
Department of Metallurgy
,
Graduate School of Engineering
,
Tohoku University
,
Sendai980-8579
,
Japan School of Metallurgy
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.
关键词:
two-phase Eulerian model
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null
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null
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null
