平面曲げ荷重によるばね綱の変形と疲労破壊のX線による研究

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The existence of decarburized surface layer affects the fatigue resistance of spring steel under cyclic load very much.In our previous experiment, fatigue resistance and the plastic deformation under cyclic load of spring steel were studied with non-decarburized and decarburized specimens by means of repeated plane bending.The plate specimens used were cut from the leaf spring stock of Si-Mn steel, approximately 6 mm thick by 60 mm wide, then quenched and tempered. In the half of the specimens, the surface remained as rolled and decarburized, and in another half the decarburized layers were removed by grinding.The test results obtained in several stress ratio showed that the endurance limit markedly decreased and the plastic deformation in the process of repeated bending increased in different manners, due to the existence of decarburized skin.In the present experiment, the behaviours of surface layer of decarburized and non-decarburized specimens under static or repeated bending were studied by X-ray diffraction method.First, the surface stresses of the both specimens in static uniform bending were measured by X-rays, at several loaded and unloaded steps, in tension and compression side separately. Then, the relations between the nominal bending stress, the measured stress by X-rays and the total surface strain were examined.
社団法人日本材料学会の論文
1967-01-15