純チタンの低サイクル疲労強度に関する研究

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In this paper, the axial strain controlled low-cycle fatigue test at room temperature in air and the fractographic study on commercially pure titanium being applied as structural material primarily in air and space vehicle, condenser tube of nuclear reactor, and future nuclear wastes treatment equipment, etc. are carried out. The attained relationships of extreme values of nominal stresses to the number of cycles at total strain ranges from 1.40% to 0.5% present a good stability. The fatigue life curves on the relationships of total strain amplitued to the crack initiated life and fatigue life are expressed by experimental equations respectively. The attained curve of fictitious stress amplitude versus fatigue life is compared with the other reactor materials such as SUS 316 and Inconel 600. The value of fictitious stress amplitude of pure titanium is less than that of SUS 316 and that of Inconel 600 at low fatigue life, but larger than that of Inconel 600 at cycle higher than 10^5,and the shape of the curve of titanium looks like that of SUS 316. The fatigue fracture shows three crack progress stages : fatigue-crack inception stage, radial stable propagation stage and final unstable fracture stage. And the inception of fatigue-crack is caused by inclusion particle.
東海大学の論文