Journal of the Society of Materials Science, Japan
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
Volume 26 , Issue 287
Showing 1-14 articles out of 14 articles from the selected issue
  • Hiroshi MUGURUMA
    1977 Volume 26 Issue 287 Pages 719-729
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
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  • Ryoichi KOTERAZAWA, Daijiro SHIMO
    1977 Volume 26 Issue 287 Pages 730-734
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    The effect of crystallographic orientation on fatigue crack propagation was studied with an 18-8 stainless steel and a carbon steel by applying the etch pit technique to observe their fracture surfaces. There was no marked preferential orientation on the fracture surfaces of both materials in contrast with the aluminum alloy previously studied. This seems to suggest that complex slip systems are operating around the tip of fatigue crack of these materials. In the case of the stainless steel, the combination of {100} fracture surface and <110> crack propagation direction was somewhat preferred, and a few cleavage-like facets associated with brittle striation-like patterns were observed on fracture surfaces, the orientation of the facets being {111} which is said to be a cleavage plane or twinning plane of face centered cubic metals.
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  • Saburo KUWANO
    1977 Volume 26 Issue 287 Pages 735-741
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Although a number of studies have been carried out on the X-ray line profile analysis of metal filings, only few have dealt with bulk metals. The purpose of this paper is to examine whether the Garrod's method, one of the X-ray Fourier analysis methods using a single reflection, is applicable to analyze the X-ray line profile of bulk metals.
    The effect of the degree of tensile deformation on the particle-size and the lattice strain of austenitic stainless steel plates was measured by the Garrod's method and by the Integral breadth method.
    The Garrod's method gave the results that the particle-size decreased linearly with increasing deformation over the range of deformation from 2 to 20%, while the lattice strain increased linearly up to 8% deformation and then reached a saturation value at 20% deformation. These results were consistent with those obtained by the Integral breadth method, although the former values were smaller than the latter. The similar result had been also recognized in the case of metal filings.
    It was, therefore, concluded that the Garrod's method is applicable to the X-ray line profile analysis of the deformed austenitic stainless steel plates and the result obtained by this method is quite reliable.
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  • Kiyoshi SAKAMAKI, Sadatoshi INADA, Hiroshi ABE
    1977 Volume 26 Issue 287 Pages 742-747
    Published: August 15, 1977
    Released: June 03, 2009
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    The effects of temperature and tensile speed under prestraining on the lower yield stress of the undeformed part of specimen under reloading were investigated. The results obtained are summarized as follows.
    (1) When the specimen prestrained at 20°C was reloaded at 20°C, -78°C or-130°C, the lower yield stress of the undeformed part was higher than that of the unprestrained specimen (as annealed) at the same temperature. Moreover, the difference of lower yield stress between the prestrained and unprestrained specimens had a tendency to increase with increasing tensile speed of reloading.
    (2) When the specimen prestrained at -78°C or -130°C was reloaded at the same temperature, the lower yield stress of the undeformed part was almost the same as that of the unprestrained specimen at -78°C and -130°C.
    (3) When the specimen prestrained at -78°C or -130°C was reloaded at 20°C, the lower yield stress of the undeformed part was lower than that of the unprestrained specimen at 20°C. Moreovr, when the specimen loaded below the lower yield stress at -130°C was reloaded at 20°C, the lower yield stress was lower than that of the unprestrained specimen at 20°C. It is considered that some changes in the states of dislocations may occur under considerably low stress at low temperatures.
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  • Kazumune KATAGIRI, Akira OMURA, Kazuo KOYANAGI, Jobu AWATANI, Tetsuro ...
    1977 Volume 26 Issue 287 Pages 748-752
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    This paper describes a special preparation technique of thin foil containing fatigue cracks created in the early stage of fatigue in copper bulk specimens and some results of direct observations of dislocation structures around the cracks by means of a 2000kV electron microscope.
    Ladder-like structures were observed ahead of the crack tips in the early stage of crack growth (so called Stage I). These structures seemed to be formed prior to the crack initiation. The dislocation density in these structures was very low, and cracks initiated within them and propagated either in the middle of the structures or along the interface between the matrix and these structures. Fine cells, dislocation entanglements and voids were not observed ahead of the crack tips in the present examination.
    From these observations, it is suggested that dislocation motion in ladder-like structures (the zone of low dislocation density) is responsible for Stage I crack growth in copper. The plastic blunting process along the band is considered unrealistic in the earlier stage of fatigue.
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  • Masaki SHIRATORI, Toshiro MIYOSHI, Hiroshi MIYAMOTO, Takao MORI
    1977 Volume 26 Issue 287 Pages 753-759
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    A model of fatigue crack propagation has been proposed. The model is essentially based on the following four assumptions:
    (1) The displacement along the crack line follows the BCS-model solution.
    (2) Every point along the crack line has a maximum amount of residual plastic deformation that it received in its history.
    (3) The rate of the fatigue crack propagation is given by the equation da/dN=C(ΔKeff)m, where ΔKeff is the effective range of the stress intensity factor and C and m are the material constants.
    (4) The effective stress range is evaluated by the stress at which the point rp* behind the crack tip opens or closes. The parameter rp* denotes the size of the cyclic plastic zone.
    Based on this model, a computer simulation of fatigue crack propagation has been carried out. The summary of the results is as follows:
    (1) When the applied stress range and the stress ratio R are held constant, the effective stress range ratio U has a constant value and it is independent of the crack length. The relation between U and R is in good agreement with Elber's equation, i. e., U=0.5+0.4R.
    (2) In the case of the decreasing ΔK test, the model can describe well the effect of R. The threshold stress intensity factor is given by the assumption that the crack will stop propagating when the COD at the crack tip is less than a certain characteristic value.
    (3) When there is a sudden change in the applied stress range, an accelerating or retarding effect occurs for a certain period.
    In these three cases, the model can express the essential features observed in the experiments. Then the simulation technique is considered to be useful for the estimation of fatigue lives.
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  • Masaki SHIRATORI, Toshiro MIYOSHI, Hiroshi MIYAMOTO, Takao MORI
    1977 Volume 26 Issue 287 Pages 760-766
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    A simpler model than the one which we reported in the previous paper has been proposed to economize the computer time. It is essentially based on the following three assumptions:
    (1) When the applied stress range is held constant, the effective stress range ratio U follows Elber's equation, i. e., U=0.5+0.4R, where R is the stress ratio.
    (2) When the applied stress varies, there appears a transition period during which the crack opening stress is affected by the previous load. This transition period continues until the cyclic plastic zone formed by the present stress range will pass over the cyclic plastic zone formed by the previous large stress range.
    (3) The rate of crack propagation is given by the equation da/dN=CKeff)m, where ΔKeff is the effective range of the stress intensity factor and C and m are the material constants.
    Based on this model, a computer simulation of fatigue crack propagation has been carried out. The summary of the results is as follows:
    (1) The model can express the retarding and accelerating effects which appear in the variable amplitude block loading tests. A series of simulation results are in good agreement with the experimental results.
    (2) The model can be applied directly to the simulation of the random loading tests.
    (3) The model can be applied to the practical problems from the viewpoint of the computer time.
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  • Mitsuru ARII, Koichi TAJIMA
    1977 Volume 26 Issue 287 Pages 767-773
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    Various kinds of cast iron containing flaky or spheroidal graphites were subjected to usual tension testing and fracture toughness testing, and their fracture surfaces were examined with a scanning electron microscope. From a viewpoint of fractography, microscopic fracture mechanism of cast iron was discussed.
    Most of the fracture surfaces of pearlitic spheroidal graphite cast iron exhibit a river pattern, and the initiating points of microcracks are found in the middle of the matrix away from graphites.
    In the case of ferritic or austenitic spheroidal graphite cast iron, their fracture surfaces generally show a dimple pattern formed by coalescence of voids of graphites.
    Such distinctly different features in the fractographs can be interpreted based on the correlation between the elastic-plastic stress distribution around graphites and the fracture stress level of matrix material. Furthermore, it was attempted to correlate fracture toughness to the appearance of the fracture surfaces.
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  • Kunio MATSUI, Takayuki SEI, Yusuke SAKAMOTO
    1977 Volume 26 Issue 287 Pages 774-778
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    The effect of deep freezing on the fracture behaviors of solid polymers has been investigated experimentally as a fundamental study of industrial cryogenic crushing operation.
    The mechanical properties of polymethyl methacrylate (PMMA) and polyvinyl chloride (PVC) are found to be critically dependent on the temperature (-180∼+120°C) at which they are deformed, as shown by the following equations (1)∼(3), but are independent of the strain-rate at which they are deformed, in the range of crosshead speed about 0.5 to 500mm/min. The values of true breaking stress σBc, and breaking strain εBc at the ductile-brittle fracture transition temperature Tc are the material-constants.
    σBBc={1-e-(Tc/T)2}/(1-e-1) (1)
    εBcB={1-e-(Tc/T)3}/(1-e-1) (2)
    εyB0=(1-e-1)·εBc=0.6321εBc (3)
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  • Kunio MATSUI, Yoshihiro ISHIZUE, Takayuki SEI, Toshiaki NAKAI
    1977 Volume 26 Issue 287 Pages 779-784
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    The effect of deep freezing on the fracture behaviors of solid polymers has been investigated by means of the drop-weight impact compression-crushing apparatus.
    In the range of low temperatures at which solid polymers are fractured, the energy input to material is independent of temperature, and increases with increasing drop-height. The strain energy necessary for deformation before the initiation of impact compression-crushing is smaller than that before the initiation of static compression-crushing. The specific surface increase ΔS and the crushing extension index CEI increase with decreasing temperature. The crushing extension index of the impact compression-crushing is the same as that of the static compression-crushing.
    In the range of higher temperatures at which solid polymers are not fractured, the energy input to material and the permanent strain decrease with decreasing temperature. The fracture-nonfracture transition temperature moves from a low temperature level to a higher temperature level with increasing drop-height.
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  • Katsuaki TAKAHASHI, Tetsuo YOSHIO
    1977 Volume 26 Issue 287 Pages 785-790
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    As an approach to the mixed alkali effect in glass, the heats of mixing in mixed alkali silicate glasses, R2O-R'2O-SiO2 (R, R'=Li, Na, K; total alkali: 35mol%, 33.3mol% and 25mol%), were measured at 25°C by solution calorimetry. The densities of the glasses containing 35mol% total alkali were also determined.
    The heats of mixing (ΔH) were negative except for the K2O rich region.
    ΔH≈-1∼-2kcal/mol SiO2
    The model proposed for the heats of mixing in fused salts mixtures containing a common anion was used for explanation of the mixed alkali effect in these glasses. In the mixed system, Li2O-Na2O, the calculated results by using the model were in general agreement with the experimental results. On the other hand, the mixed alkali effect could not be observed on the volume per mol SiO2.
    It is concluded from these results that the interaction between unlike ions is a more important factor than the geometrical factor in explaining the mixed alkali effect.
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  • Taketoshi MATSUURA
    1977 Volume 26 Issue 287 Pages 791-795
    Published: August 15, 1977
    Released: June 03, 2009
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    Nowadays, resin mortar (concrete) is widely used in various fields. The flowability of resin mortar in the uncured state is one of the important properties for its usage. The usual methods of measuring flow of fresh cement mortar (concrete), such as the flow test and the slump test, are, however, inapplicable on resin mortar because of adhesiveness of resin mortar.
    This paper describes a method of measuring resin mortar flowability using a rotational viscometer and the characteristic points of resin mortar flowability, obtained by this method. The rotational viscometer used was of a Couette type with the following dimensions;
    Inner cylinder: 120mmφ, 120mm height.
    Outer cylinder: 180mmφ, 200mm height.
    The results obtained are summarized as follows;
    (1) The present rotational viscometer is well suited for the study of resin mortar flowability. When compared with cement mortar having a similar appearance, resin mortar had higher viscosity but lower yield stress.
    (2) Super fine silica powder (7mμφ) increased the yield stress of resin mortar.
    (3) The amount of CaCO3 powder showed large influence on both the viscosity and compressive strength of resin mortar. The minimum value in viscosity and the maximum value in compressive strength were obtained at 25-35% of total aggregate.
    (4) From the temperature dependence of resin mortar viscosity, the activation energy of flow for resin mortar was found to be 7.1Kcal/mol, which is nearly equal to that of the resin (7.6Kcal/mol). This similarity in activation energy indicates that the viscosity of resin is a dominant factor in resin mortar viscosity.
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  • Toshimitsu YOKOBORI, Takeo YOKOBORI, Hiroshi OUCHI, Hisao SASAKI
    1977 Volume 26 Issue 287 Pages 796-800
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
    In the present article the studies on the mechanical behaviour of vascular substitutes of two kinds, that is, Tetron and Dacron, have been experimentally carried out by tensile testing and stereo microscopy. From the results it is concluded that vascular substitutes made of Dacron are more suitable for clinical use than of Tetron as far as the mechanical behaviour of the virgin state is concerned.
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  • K. Ohji
    1977 Volume 26 Issue 287 Pages 801-811
    Published: August 15, 1977
    Released: June 03, 2009
    JOURNALS FREE ACCESS
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