1994 Fiscal Year Final Research Report Summary
Study on Thermal Shock of Sintered Tungsten Alloys for a First Partition of Nuclear Fusion Furnace by the Method of Fracture Mechanics
| Project/Area Number |
05650103
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Nagaoka College of Technology |
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Principal Investigator |
KOBAYASHI Satoshi Nagaoka College of Technology, Department of Mechanical Engineering, Professor, 機械工学科, 教授 (30042782)
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| Co-Investigator(Kenkyū-buntansha) |
MUTOH Yoshiharu Nagaoka University of Technology, Department of Mechanical Engineering, Professo, 工学部, 教授 (00107137)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Sintered alloy / High temperature / Strength / Thermal shock / Fractography / Fracture / Tungsten / Notch |
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| Research Abstract |
Mechanical Properties of W-Ni-Fe sintered alloys with the various volume fractions of tungsten particles were investigated at elevated temperature. 0.2% proof stress and tensile strength of sintered tungste alloys by tension tests, which were higher than those of the other heat-resistance alloy such as 18Cr-8Ni steel, decreased with increasing temperature. Fracture toughness of the sintered tungsten alloys decreased with increasing volume fraction of tungsten particles. When the volume fraction of tungsten particle is low, a stable crack dominantly grows in the Ni-Fe matrix phase, resulting in high toughness. Three point bending tests were carried out in order to study the notch strenght of sintered tungsten alloys. There existed the linear elation between the bending load and the crack lenght. The crack initiation load indicated the low values for the tungsten alloys with high volume fraction of tungsten particle. A crack in the tungsten particle or the tungsten-tungsten grain boundary was observed by the the thermal shock tests for the sintered tungsten alloys. This crack never propagated into the otether tungsten grain or the matrix phase although the thermal shock tests were repeated. The stress distributions around the tungsten particles were analyzed by using a finite element method, and they varied by the change of the volume fraction of tungsten particles. Mechanism of crack initiation in the tungsten particle was investigated by the calculated stress distributions.
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