巻号一覧
48 巻, 10 号
選択された号の論文の11件中1～11を表示しています
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末吉 秀一, 末永 勝郎, 田中 良平1984 年 48 巻 10 号 p. 965-971
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe fatigue limit of hypo-eutectoid graphitic steels was studied in connection with microstructural factors such as the mean ferritic grain size dF (mm), the volume fraction of graphite f, the mean graphite nodule diameter dG (mm), and the mean ferrite path between graphite nodules λ.
By the multiple regression analysis the fatigue limit σW (MPa) was expressed as follows:
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The effect of dG was smaller than that of dF.
Non-propagating microcracks were observed on the surface of smoothed specimens subjected to the repetition of 107 cycles at the stress of the fatigue limit, and furthermore, the criterion as to whether non-propagation of a microcrack can occur or not was found to be related to the microcrack length, the cyclic stress and the mean ferritic grain size. Thus it was concluded that the fatigue limit is not the critical stress for crack initiation but is the maximum stress below which the microcrack can not grow continuously.
Aspects of fatigue fracture surface depended on the microstructure of graphitic steels, and the amount of facet type fractures increased with decrease in mean ferrite path between graphite nodules.
The endurance ratio of the graphitic steels was in the range from 0.52 to 0.60.抄録全体を表示PDF形式でダウンロード (1648K) -
末吉 秀一, 末永 勝郎, 田中 良平1984 年 48 巻 10 号 p. 971-977
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーFatigue tests were carried out on hypo-eutectoid graphitic steels by using notched and holed specimens, and the propagation behavior of fatigue cracks was investigated in connection with microstructural factors.
At the root of notched specimens of graphitic steels, fatigue cracks were observed to grow in a zig-zag way through graphites adjacent to the crack tip.
When a cyclic stress was below 60 per cent of the yield stress or 0.2%-proof stress, the fatigue crack propagation rate, dl⁄dN, of holed specimens was related to the stress intensity factor range ΔK, and paris-Erdogan’s relationship, dl⁄dN=C(ΔK)m, held in all cases. However, the value of m decreased with increase in the square of mean graphite nodule diameter and the reciprocal square root of mean ferrite path between graphite nodules.
When a cyclic stress exceeded the above mentioned stress, the fatigue crack propagation rate was expressed as follows:
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\ oindentwhere D, E and F are constants independent of the microstructure, on the other hand, n and k depend on it. Microstructural effects on the fatigue crack propagation rate were considered to be mainly caused by microstructural effects on n, because variations of the value of n were larger than those of k.
The value of n in graphitic steels examined in this work enlarged, as the value of m decreased.抄録全体を表示PDF形式でダウンロード (1354K) -
大西 忠一, 東 健司, 中谷 義三1984 年 48 巻 10 号 p. 977-982
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーSuperplastic behaviors were observed in a commercial JIS A5083 aluminum alloy which had been heat-treated to have an equiaxed recrystallization structure with a grain size of about 7 μm.
In the optimum condition in this work, at 763 K and at 1.11×10−3 s−1, the specimen showed the maximum elongation of 460%. The plots of the maximum engineering stress against the initial strain rate in the temperature range from 613 to 783 K showed the characteristic S-shape feature, and the maximum m-values measured from these plots were about 0.5. The grain coarsening during the superplastic deformation was found to be proportional to the true strain of the specimen, and to be more remarkable with rising temperature. In conditions of an appreciable grain coarsening, the strain rate corresponding to the maximum elongation shifted to a lower value with rising temperature, which was a tendency different from that predicted by deformation behaviors in common superplastic materials.
Generation and development of striation bands on the specimen surfaces deformed superplastically and disintegration of the texture during deformation were also observed.抄録全体を表示PDF形式でダウンロード (2093K) -
大和 宣介, 後藤 和弘1984 年 48 巻 10 号 p. 983-989
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe solubility of carbon dioxide in Na2O-P2O5-SiO2 melt has been determined by using a themobalance in the range from 0.5 to 0.9 mole fraction of sodium oxide at 1373 K to 1473 K under various partial pressure of CO2 in O2-CO2 mixture. The experimental samples have been prepared from sodium carbonate, silica, and sodium metaphosphate. The solubility of carbon dioxide was calculated from the weight change of the melt. The measured solubility of carbon dioxide in Na2O-SiO2-P2O5 melt can be expressed by the experimental equations as follows.
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\ oindentwhere A, B, C and D are constants for various mole ratios of Na2O/SiO2 and T is the absolute temperature. The solubility of CO2 gas increases with decrease of temperature, with increase of partial pressure of CO2, and with decrease of the contents of SiO2 and P2O5.抄録全体を表示PDF形式でダウンロード (867K) -
佐藤 昭規, 昆 謙造, 辻川 茂男, 久松 敬弘1984 年 48 巻 10 号 p. 989-995
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe effect of misorientation on the intergranular cracking of cathodically hydrogen-charged specimens under the external tensile stress was investigated on Inconel alloy 600 with coarse columnar crystals. As the deviation of the growing direction from ⟨100⟩ orientation was within 10°, the grain boundaries were treated as simple tilt boundaries with ⟨100⟩ rotation axis. Misorientation of a grain boundary is described in terms of the three angles, relative tilt angle (ω), tilt angle (α) and symmetrical tilt angle (θ), determined with {100} planes nearest to the grain boundary plane. The depth of intergranular cracking (D) of the specimens water-quenched and sensitized at 973 K for 7.2 ks changed over a wide range up to 200 μm. There is no clear relation between D and ω. It was found that D increased with decreasing α in classified cases of ω=2°∼10° and ω=40°∼45°, and also with decreasing θ. This result shows that grain boundaries of which the planes are close to {100} of adjacent crystals have higher susceptibility to cracking. Markedly lower susceptibilities of symmetrical coincidence boundaries such as ∑5 and ∑13 are recoganized against the normal relation of D with θ. Shallower transgranular cracks compared with intergranular cracks were always observed along {100} plane. The relationship between misorientation of grain boundaries and carbide precipitation is not clear, expect the fact that symmetrical coincidence boundary and tilt boundary with ω=2°∼10° are carbide-free.抄録全体を表示PDF形式でダウンロード (1561K) -
荻野 和巳, 西脇 醇, 細谷 陽三1984 年 48 巻 10 号 p. 996-1003
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーIn order to obtain precise density of molten metal at high temperatures, a new manometer method based on an X-ray transmission technique was developed. After confirmation of the accuracy of the method by the measurements of standard liquids at room temperature, the density of molten iron was measured. The relation between the density of molten iron and the temperature was as follows:
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\ oindentThe densities at temperatures near the melting point and the temperature coefficient corresponded to the relatively high values obtained in previous works. Direct measurements of volume expansivity and the volume change on melting of iron were made to ascertain the results obtained by the manometer method. The expansivity and the volume change determined by the dilatometric method were (1.88±0.11)×10−3 K−1 and (2.25±0.08)%, respectively, which were in good agreement with those calculated from the results of the manometer method. It was recognized that the temperature coefficients of the density of molten iron obtained experimentally in the present and previous works had a tendency to deviate positively from those predicted by the empirical formulas on the thermal expansion of molten pure metals.抄録全体を表示PDF形式でダウンロード (1450K) -
荻野 和巳, 西脇 醇, 細谷 陽三1984 年 48 巻 10 号 p. 1004-1010
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーDensities of molten Fe-C alloys were determined by the manometer method developed in a previous study. The density at 1873 K showed the minimum value at about 3.5 mol%C and the maximum value at about 6 mol%C. The change in volume expansivity with carbon content was similar to that of the density. The molar volume at 1873 K deviated slightly positively from the additive law in the concentration below 2.3 mol%C and negatively above 2.3 mol%C. The deviation at 2023 K or above that temperature was negative over the whole range of concentration except very low carbon content. The partial molar volumes of iron and carbon in the melts with carbon below 2.0 mol% and above 7.0 mol% were nearly equal to those of α and γ phase, respectively. The deviation of molar volume from ideal mixing was also compared with available information on the relation between the excess entropy of mixing and the volume change on mixing in binary iron alloy, and the interaction parameter between iron and carbon was deduced from the regular solution model. The results obtained could be explained by the speculation that the features of solid phase before melting remained in the short range order structure of the melts.抄録全体を表示PDF形式でダウンロード (1011K) -
鈴木 寿, 松原 秀彰, 斉藤 武志1984 年 48 巻 10 号 p. 1011-1016
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe transverse-rupture strength of a TiC0.5N0.5-19 mass%Mo2C-23 mass%Ni alloy sintered in nitrogen, HIP-treated in argon and finally resintered in nitrogen at 1723-1823 K in each treatment was in detail studied as a function of the microstructural defects.
Pores were observed as the structural defects in the specimens sintered in nitrogen. During the HIP-treatment, the pores changed to nickel pools with the size far smaller than that of the pores, resulting in the sharp increase in the strength of HIP-treated specimens. The nickel pools changed again to pores, when the specimens were resintered. The strength of specimens resintered at a higher temperature, however, showed a strength as high as 3.2 GPa, suggesting that the number density of micro-pores decreased greatly by the resintering. Discussion has been made on these results.抄録全体を表示PDF形式でダウンロード (1636K) -
鈴木 寿, 伊藤 吾朗1984 年 48 巻 10 号 p. 1016-1021
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe ductility at intermediate temperatures has been examined for several copper specimens having grain size of 0.3-0.4 mm, paying attention to the amount of impurity of sulfur dissolved in the matrix. Tension tests were conducted at temperatures ranging from 473 K to 723 K at strain rates from 4.6×10−4 s−1 to 4.6×10−2 s−1. In commercially available pure copper containing about 6 mol ppm S, the well-known phenomenon of intermediate temperature embrittlement was observed to appear at about 623 K at a low strain rate. However, the embrittlement became negligible, as the amount of impurity of sulfur decreased. It was found that the embrittlement entirely disappeared in the pure copper specimen containing S less than 1 mol ppm and, for instance, in the specimen prepared by adding 12 mol ppm Ti to commercial pure copper, and that dynamic recrystallization during the tests at intermediate temperatures occurred markedly in these specimens. Based on these results, it was concluded that the intermediate temperature embrittlement is not an inherent phenomenon in “pure” copper.抄録全体を表示PDF形式でダウンロード (1749K) -
落合 庄治郎, 安部 研吾, 長村 光造1984 年 48 巻 10 号 p. 1021-1027
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーThe static stress concentration in the fibres adjacent to broken fibres, the stress distribution along the fibre axis in the broken and intact fibres and shear stresses between broken and intact fibres in elastic fibre-metal matrix composites were calculated using a two-dimensional model applying the shear lag analysis. The effects of plastic deformation of matrix and those of interfacial debonding on the stress concentration and stress distribution were quantitatively estimated. The following points were clarified in a qunatitative manner. (1) When the interfacial bonding strength is lower than the yield stress of the matrix in shear, the interfacial debonding occurs, when applied stress becomes higher than the threshold stress for the interfacial debonding to arise. After the interfacial debonding occurs, the length of a region showing debonding increases rapidly with increasing stress level. The stress concentration in the fibres adjacent to broken fibres decreases rapidly due to the interfacial debonding. (2) When the interfacial bonding strength is much higher than the yield stress of the martix in shear, the matrix yields in shear, when applied stress becomes higher than the threshold stress for shear yielding of the matrix to arise. After the shear yielding of the matrix, the stress concentration in intact fibres decreases with increasing stress level. When the yield stress, the shear modulus and the strain hardening coefficient of the matrix are low, the stress concentration factor in intact fibres decreases rapidly with increasing stress level. (3) The interfacial debonding and shear yielding of the matrix in shear act to reduce the stress concentration factors in the intact fibres, which, on the other hand, causes to increase the critical length of the fibre necessary for the reinforcement. Thus the efficiency of reinforcement is reduced, especially by the interfacial debonding.抄録全体を表示PDF形式でダウンロード (1037K) -
落合 庄治郎, 安部 研吾, 長村 光造1984 年 48 巻 10 号 p. 1028-1034
発行日: 1984年
公開日: 2008/04/04
ジャーナル フリーStrong boron fibre-reinforced aluminium matrix composites will be obtained by the hot-pressing technique, if the interfacial conditions are controlled within the range of temperature and time where degradation of fibres due to the interfacial reaction is not caused. On the basis of this idea composite specimens were prepared. It was found that the hot-pressing at 773 K for 1.2 ks under a pressure of 50 MPa gave rise to a strong interfacial bonding but not degradation of the fibres due to the interfacial reaction, yielding high strength composites. The tensile behawiour of the composites with various interfacial conditions were investigated. The effects of interfacial conditions on the deformation and fracture behaviour of the composites were well understood by the experimental results and the results of the computer simulation.抄録全体を表示PDF形式でダウンロード (1560K)
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