The Dependency of Stress on the Diffraction Plane in thePolycrystalline Metals

The loading and residual stresses measured by using X-ray stress measurment depend on diffraction plane. In order to make clear its cause, the several models on elastic and plastic deformations are developed and the theoretical values are compared with measured ones. It was found that the dependencies of measured stress on the diffraction plane can be explaned by accepting Reuss's model for elastic deformation and Taylor's model for plastic deformation

Fatigue Strength of Age-Hardened Al-Zn Alloys under Repeated Tensile Loading

Effect of the soft surface layer that was formed on low temperature aging of Al-Zn alloy on fatigue strength was studied under repeated tensile loading. Vickers microhardness test revealed that there existed less hardened region in the vicinity of grain boundary and surface, and that the region extends 50 to 100μm from the surface inward. From the plot of the stress amplitude against the number of cycles to failure, it is concluded that the presence of less hardened surface layer strengthens fatigue resistance of the age hardened Al-Zn alloys containing 8 to 16mass % Zn under the repeated tensile loading

A Study of Anisotropic Workhardening

This paper deals with the stress-strain curves of single crystal and polycrystal considering the workhardening and the anisotropy which is due to the difference of workhardening on each slip system. The results obtained are summarized as follows: 1) The equations of workhardening on each slip system are derived according to the dislocation theory. 2) And it is found that the stress-strain curves of Cu single crystal and polycrystal calculated by using the workhardening equation with proper coefficients agree well with the experimental values

The Effects of Time Constant and Absorption on Stress Measured by X-ray Diffraction Method

The diffracted intensity of X-ray depends upon several physical and geometrical factors such as structure, multiplicity, absorption and Lorentzpolarization and measuring conditions such as time constant and scanning speed of detector on counter method[l]. For analyzing on the X-ray stress measurement, especially, profile shape of X-ray diffraction which is affected by geometrical factors such as absorption and Lorentz-polarization is very important. In order to eliminate these factors affecting the stress measured by using X-ray, the correcting factors were introduced and those theoretical values were calculated. After this theoretical calculation, it is found that as the half value breadth increases the difference between the stress measured by using X-ray and the corrected one becomes larger and larger under same measuring condition. When the ideal diffracted intensity of X-ray is assumed Cauchy distribution the measured stress depends upon measuring condition for same specimen, but it is independent of measuring condition in Gauss, distribution. Consequently, it is found that the stress measured by using X-ray must be corrected under each measuring condition and the method of correction is made clear and proved experimentally in this paper

Effect of Specimen Thickness on Aging and Fatigue Strength of Al-Zn Alloys

Repeated tensile fatigue strength of the low temperature age-hardened Al-Zn alloys is investigated varying the specimen thickness. Fatigue strength of the age-hardened specimens decreases with the specimen thickness when the specimen is thinner than a certain thickness, whereas fatigue strength of non age-hardened specimens, i.e., pure aluminum and dilute Al-Zn alloy, does not depend the specimen thickness. The dependence of fatigue strength on the thickness of age-hardened specimen is considered to be caused by the decrease of the strength of specimen as a whole, as a result of increase in volume ratio of the soft surface layer formed after age-hardening with decreasing specimen thickness

Precipitation Hardening and Effect of Surface Layer on the Fatigue Strength of an Al-1.2mass% Si Alloy

Dependence of precipitation hardening on the distance from specimen surface and effect of the surface layer on the fatigue strength of an Al-1.2mass% Si alloy were studied by microhardness test, transmission electron microscopy and repeated tension fatigue test. Rate of age-hardening was slower in the vicinity of surface than in the interior of the specimen aged at 423K after quenching from 853K. The result of the electron microscopy was that the size ot Si precipitates formed in the vicinity of surface was smaller than in the interior of specimen aged for 6ks at 423K. This difference was considered to be caused by the effect of the surface as vacancy sinks which slowed down the growh of Si precipitates in the vicinity of the specimen surface. A specimen surface layer whose hardness was different from that of the specimen interior was formed at the vicinity of the surface when the specimen was aged at relatively low temperature such as 423K. The fatigue strength in repeated tensile test ot the specimen did not depend on whether the specimen surface layer was present or not

Overexpression of Nuclear Receptor 5A1 Induces and Maintains an Intermediate State of Conversion between Primed and Naive Pluripotency

Naive and primed human pluripotent stem cells (hPSCs) have provided useful insights into the regulation of pluripotency. However, the molecular mechanisms regulating naive conversion remain elusive. Here, we report intermediate naive conversion induced by overexpressing nuclear receptor 5A1 (NR5A1) in hPSCs. The cells displayed some naive features, such as clonogenicity, glycogen synthase kinase 3β, and mitogen-activated protein kinase (MAPK) independence, expression of naive-associated genes, and two activated X chromosomes, but lacked others, such as KLF17 expression, transforming growth factor β independence, and imprinted gene demethylation. Notably, NR5A1 negated MAPK activation by fibroblast growth factor 2, leading to cell-autonomous self-renewal independent of MAPK inhibition. These phenotypes may be associated with naive conversion, and were regulated by a DPPA2/4-dependent pathway that activates the selective expression of naive-associated genes. This study increases our understanding of the mechanisms regulating the conversion from primed to naive pluripotency

V マゲ ノ スプリング バック ニ カンスル ケンキュウ

The relationships between stress and strain, and r-values in three directions of thin steel plates are obtained by simple tension test. Using these results, the first stage bending by V-form die are analyzed by the relationship between curveture and bending moment, which considered anisotropy of material. A new method for analyzing the bending are shown. Stroke (Y), Load (P), Spring-back (△θ) and Bending-angle (θ) are calculated by the method and compared with their experimental values. The calculated results about Y-△θ and Y-θ are good agreement with experimental values, respectively

セツサク オヨビ ケンサク カコウザイ ノ ザンリュウ オウリョク ニ カンスル ケンキュウ

The residual stess on cutted and grinded steel was measured by using X-ray stress measurment method. The results were obtained as follows ; 1. The residual stress components were obtained by using the general form for stress analysis under triaxial stress state in X-ray stress nesyerment. 2. In cutting, depth of cut influence on residual stress. In finish cutting, tensile residual stress become very large. 3. In glainding, the residual stress become smoll as depth of cut and feed soead of table is smoller. 4. Searing stress components are not so large as other components

AL 3MASS% MG ゴウキン ノ ヒロウ キョウド ニ オヨボス ヒョウメンソウ ノ エイキョウ

The surface layer of an Al-3mass%Mg alloy annealed at high temperature and its effect on the fatigue strength were studied by measurements of microhardness, electrical resistivity and number of cycles to failure under repeated tensile loading. The results obtained are summarized as follows. (1) The surface layer was softer than the interior. The thickness of this layer was about 50 μm. (2) It is isterpreted that the formation of this soft surface layer was becaused by the depletion of Mg atoms due to oxidation of Mg atoms near surface. (3) The soft surface layer has an effect of rasing the fatigue strength to repetitive tensile loading