W-Ni-Fe系焼結合金の機械的性質に及ぼすひずみ速度効果

概要

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Dynamic tensile properties of W-Ni-Fe alloys has been studied for a test temperature at 20°C and for a high strain rate using high speed impact tension testing machine of a constant speed type. With this machine, high speed uniaxial tensile tests of the materials, 95.5W-3.0Ni-1.5Fe, 93.2W-4.5Ni-2.3Fe and 91.3W-5.8Ni-2.9Fe alloys, were carried out to obtain the relation between tensile strength and tensile speed in the range up to 15 m/s. Also, the effect of circumferential notch having various notch root radii on the fracture behavior under dynamic tension was investigated. Tensile strength and ductility of specimens were measured. These experimental results seems to suggest that the dynamic tensile strength is larger than the static one. The elongation also seems to be lower than static one with increasing tensile speed. This seems to show the necessity to consider the factors such as the strain rate effect in stress strain relation, etc.. It was proved that fracture condition of these specimens can be explained, based on the comcept of "Linear Notch Mechanics". Tensile fracture behavior of notch specimen is controlled approximately only by the values of notch root radius and ultimate tensile strength independently of the other dimensions of the specimen. By considering these fracture textures, a fracture mode of specimens was proposed and the fracture mechanism was discussed.
社団法人粉体粉末冶金協会の論文