Ｘ線回折線半価幅と硬度検査を伴う炭素鋼の疲労累積に関する研究*

概要

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The authors have so far been presenting papers for this magazine their creative measurement and study of fatique energy accumulation. The titled experiment has given them interpretation about the problem as follows. (a) Early in the stress cycle up to about 10^2, the microscopic fatigue plastic work in the smaller over-stress repeat induces work hardening of the material as a whole, while that in the larger one it generates heat and softens the material. (b) In the same period as above, under any stress amplitude, the machining-affected strains are released and the local stresses equalized. After the period, formation of slip bands, fragmentation of crystalline grains and birth and propagation of cracks occurs successively until the specimen fails in fatigue. (c)　In view of the present result, the series of the authors’ recent study paying positive attention to the heat generation is considered to devote some to the similar study, in which up to now most of other researchers are seemed to have neglected the influence of the temperature rise during the tests and examined mainly the fatigue hysteresis loop area.