In the X-ray measurement of residual stress at most accuracy is required and the appearance of the measured value is important. It is well known that if X-ray diffraction pattern is sharp, that will be good reappearance of the measured value. In hardened and ground bearing steel, however, merely extremely broadened diffraction pattern can be gained. In this case, it is questionable whether the measured value is reliable or not.
From bearing steel, we made seven kinds of test pieces which were heat treated. They were found in different levels of hardness, and we practiced measurement, of their stress at their respective levels. Consequently, it was found that the scattered range of their measured value was 6∼13kg/mm² and between broadened diffraction pattern and sharpened one, the difference at scattered range of the measured value was not particularly noticed.

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It is the object of this paper to make it clear that the form of hysteresis loops and its changes, which were obtained during the cyclic tension compression, were numerically related by a simple rule to the Meyer hardness values of the cyclically strained material.
(1) The Meyer indices n of the cyclically strained carbon steels and copper were nearly equal to x+2, where x was the value of the strain hardening indices determined from the hysteresis loop. The value x was almost constant during the cycling of constant strain amplitude.
(2) The cyclic softening of work hardened copper as well as the cyclic hardening of annealed copper, expressed by the change of stress amplitude of hysteresis loop, corresponded numerically to the change of the Meyer hardness values which were measured under constant‘hardness strain’¹⁾.
(3) When the materials were subjected to tension compression, the following rule was obtained not only over the hardening or softening period but also over stable state of cycling. Namely, Meyer hardness P_m vs. hardness strain ε_h relationships of the cyclically stressed materials coincide with the relationships between the Ya value, true stress Y multiplied by material constants a (2.95≤a≤3.3), and true strain ε of hysteresis loops.
(4) The Meyer hardness measured of the specimens unloaded from the tension side during the cycling was slightly lower than the value measured after the unloading from the compression side.
It will be concluded from these results of the present investigation that the cyclic hardening (Or softening) of the material can be determined either by the change of stress (Or strain) amplitude under constant strain (Or stress) amplitude or by the change of Meyer hardness values or of Vickers hardness values.

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Bending yield stresses (Spring limit) of copper alloy and stainless steel flat springs decrease considerably when they are subjected to plastic deformation by stretching or bending them in the opposite derection. Hereunder is presented a report of the investigation performed of the degree of decrease in spring limit and the material factors in the specimens in heat treatment and the effect of the rolling direction on the axis.
The results are as follows:
(1) The spring limit of a thin shaped flat spring decreases when the stress applied on the spring has a opposite direction to pre-stress, and increases when it has the same direction.
(2) The spring limit of the specimen subjected to pre-stretching stress decreases wlth increase of pre-plastic strain over the elastic limit, and is constant when the pre-stretched plastic strain becomes higher than 0.2%. This constant minimum spring limit K_bmin is about 10 to 25kg/mm², and this value is about 1/10 to 1/2 of the spring limit before deformation.
(3) The spring limit of the specimen subjected to pre-bending stress increases by the bending, and decreases by bending it in the opposite direction. The spring limit that decreased by bending it in the opposite direction can be improved as the deformation increased on the opposite side.
(4) The spring limit of the specimens containing different materials, heat treatments, degree of cold reduction and specimen axis decrease similarly when pre-plastic strain applied, and these factors will affect K_bmin a little.
(5) The decrease of spring limit by stretching or bending plastic deformation is due to Bauschinger effect.

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The authors have applied X-ray diffraction techniques to the study of low-cycle fatigue in order to discuss its macroscopic behavior from the microscopic point of view. In previous papers, it was reported that the formation and development of subgrain were the main features of microstructural change caused by strain-cycling till its failure. And a good correlation was obtained between the particle size measured by the profile analysis of the X-ray diffraction peaks and the damage fraction in low carbon steel under constant strain-cycling.
Further investigation on microstructural behavior of annealed low-carbon steel under cyclic straining was made by conducting two-step strain-cycling tests, and the following was obtained as the results of this study:
(1) Under a constant strain range, the stress range increased rapidly during the first dozens of cycles and, later, tended gradually to saturate. In the two step strain-cycling, the stress range increased with the increase of strain range and decreased with the decrease of strain range.
(2) During the two-step strain-cycling, the mode of change of integral breadth of X-ray diffraction peak was very similar to that of the stress range. However, a small value of the integral breadth was obtained from the failured specimen.
(3) The abrupt change in the integral breadth consequent on the change of strain range is interpreted by the profile analysis of the diffraction peaks that it was occasioned by the change in the extent of micro strain.
(4) However, little effect was observed of the change of strain range on the particle size.
(5) A fairly straight line was obtained between the stress range and the integral breadth of higher angle diffraction peaks.
(6) The value of integral breadth at failure was generally lower than the value obtained from the above plotting of stress range versus integral breadth. However, the value of integral breadth inside of the failured specimens was higher than that on the surface.

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One of the important problems respecting the X-ray method of stress measurement is concerned with the residual stresses induced in polycrystalline metals by plastic deformation. Many experimental results that have so far been obtained by the X-ray method show that the axial residual stresses induced by uniaxial deformation do not satisfy the macroscopic equilibrium over the cross section of a specimen. Moreover, the magnitude and sign of the fictitious stress depend upon the crystallographic plane that is to be used to diffract the X-ray beam. For example, the axial residual stress of a specimen of α-iron deformed in tension is approximately in equilibrium if measured with respect to {211} by Cr-Kα radiation. On the other hand, if measurements are made with respect to {220} by Fe-Kα, the residual stress distribution will not satisfy the equilibrium giving a fictitious tensile stress. A fictitious compressive stress will be obtained if measurements are made with respect to {310} by Co-Kα.
Since the lattice spacing is taken as gage length when measurement of stress is made by the X-ray method, the two following factors are considered to account for the above-mentioned fictitious stresses.
(1) The lattice strain of each crystal constituting a polycrystalline aggregate is inevitably influenced, so far as compatibility must be satisfied, by the elastic and the plastic deformation behavior of the surrounding crystals.
(2) The information to be obtained by the X-ray method is restricted to those select crystals which are correctly in the direction that will satisfy Bragg's condition.
The first fundamental interpretation of the fictitious residual stress phenomenon was proposed by Greenough. He introduced a relationship between the microscopic residual stress resulting from uniaxial tension and the residual lattice strain measured by X-rays. However, his theory does not seem to be adequate for such metals as α-iron since he assumes elastic isotropy, and the theory is based on Taylor's theory, in which plastic anisotropy is not considered.
In the present investigation, the fictitious residual stress induced in polycrystalline α-iron by uniaxial plastic deformation was theoretically interpreted considering elastic and plastic anisotropy. The analysis is based on the following assumptions:
(1) Each crystal constituting an aggregate under plastic deformation is of equal strain.
(2) In the loading condition, the stress in each crystal corresponds to the flow stress in the multiple slip region of a single crystal with the same orientation.
(3) The elastic constants of a polycrystalline aggregate are calculated from those of the constituent crystals according to the Reuß or the Voigt model.
The theoretical result thus obtained will efficiently elucidate the published experimental results qualitatively.

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Various studies have so far been made of fatigue crack propagation about all kinds of engineering materials, but as its essential mechanism has not yet been known an experiment was performed on plane bending fatigue test using a Polycarbonate plate for specimen, and the same is reported hereunder in this paper.
The relation that the differentials of the crack length due to the number of repetitions is proportional to the crack length holds with polycarbonate as it does with metals. The number of striations is equal to the number of cycles under high stress, but it is not equal to the number of cycles under low stress. The main crack is propagated by the repeated stress under high stress, but the crack is propagated after the propagating of shear yielding band for several number of cycles under low stress. The relation between the macroscopic propagating rate and the stress intensity factor range follows the formula presented by Paris for metals, and it is certified that the fatigue fracture mechanisms differ essentially under the high and low stresses.

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In order to be equipped with necessary resources for establishing the standard (JIS) of impact testing of rigid PVC compounds, the Charpy and Izod impact testing was carried out of eight kinds of rigid PVC compounds by various testing methods, i. e., JIS K 6745, ISO R 179 and ASTM D 256. The test specimens were machined from the compression moulding plates of 4mm in thickness, which were made according to ISO R 293. The results obtained are summarized as follows
(1) There are roughly proportional relations between any two of the various impact strengths obtained from different compounds, i. e., the ratio ss·ISO·a_kC/JIS·a_kC takes roughly a constant value of a little less than 0.4, the ratio ss(e) ISO·a_kC/JIS·a_kC of about 0, 3, the ratio S·ISO·a_kC/JIS·a_kC of a little over 0.4, and the ratio ASTM·a_kI/JIS·a_kC of about 0.7, where JIS·a_kC, ss·ISO·a_kC, ss(e)·ISO·a_kC and S·ISO·a_kC represent Charpy impact strengths measured by JIS, standard small ISO, standard small ISO (Edgewise notch) and standard ISO Charpy impact test specimens respectively, and ASTM·a_kI is Izod impact strength by ASTM specimen.
(2) To insure effective discrimination among the impact resistances of compounds, shallower notch in the shape of Charpy impact specimen, as in JIS specimen, is preferable to deeper notch as in ISO specimen.
(3) It is found that there remain some problems to be solved, i. e., the influence of blow energy (Capacity of pendulum hammer) on the absorbed energy or on the fracture form, and no separation of fractured specimen into two halves etc., in the impact testing of modified PVC compounds such as high impact PVC compounds.

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The waste product of carbide after the extraction of acetylene gas, known as called cardidemud, is for the most part practically being thrown away in most synthetic chemical plants. In view of the fact that the principal composition of this mud is Ca(OH)₂ we have made experiments and found out that carbidemud can be utilized to produce special sort of cement different from common portland cement by making its mixture with cinder ash and quenched blast furnace slag.
We have named this special cement“CM-cement.”The characteristics of CM-cement are:
(1) The ingredient material being the waste product of plants, the cost is outstandingly low, and available near the plant.
(2) The maximum compressive strength of 300kg/cm² is available in 28 days in standard curing.
(3) There is almost no febrility apt to be occasioned by the hydration after mixing.
(4) The hydration of CM-cement is in general quite similar to that of portland cement, but its strength at early age is lower than that of normal portland cement.
(5) The specific weight of the concrete with this cement is 20% lighter than normal concrete.
The CM-cement with the above mentioned characteristics will be used in making precast concrete blocks, plaster works of buildings, in prevention construction of slope failure, in grouting works and in construction of foundation works and simple pavements. These are important ways to utilization of waste materials for civil and architectual construction materials. This CM-cement is considered to be effective also in soil improvement works. More economical and efficient works will be developed in construction of foundation works for super structures, in reclamation works, in banking and in readjustment of steep slopes.

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