材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
32 巻 , 357 号
選択された号の論文の17件中1~17を表示しています
  • 井上 達雄
    1983 年 32 巻 357 号 p. 594-604
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 金澤 健二, 山口 弘二, 小林 一夫
    1983 年 32 巻 357 号 p. 605-609
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Cyclic stress-strain curves were obtained by the incremental step method for a carbon steel SB 49 and a chromium-molybdenum steel SCMV 4. The temperature and strain rate dependences of the cyclic stress-strain curves were discussed and the curves were compared with those obtained by the companion specimens method. The conclusions obtained were as follows:
    (1) Cyclic hardening and cyclic softening behaviors were observed for SB 49 and SCMV 4, respectively. The cyclic stress-strain curve lay at the higher stress level side than the monotonic stress-strain curve for SB49; for SCMV 4 it was the other way.
    (2) The cyclic stress-strain curve depended on strain rate. With decreasing strain rate, the stress amplitude for SB49 increased at 200 and 300°C, but decreased at 400 and 500°C. Similar dependences were observed in SCMV 4 steel.
    (3) The cyclic stress-strain curve can be expressed very well by the experimental equation as Δεt/2=(Δσ/2)/E'+{(Δσ/2)/K'}1/n'
    (4) For both materials, the cyclic stress-strain curve obtained by the incremental step method coincided with that obtained by the companion specimens method.
    (5) The cumulative damage against the number of blocks to failure in the incremental step tests ranged from 2 to 1/2 for both materials.
  • 猪狩 敏秀, 瀬戸口 克哉, 山内 雅文
    1983 年 32 巻 357 号 p. 610-614
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper presents the results of the elastic-plastic deformation analysis using a cyclic stress-strain curve with an intention to apply this method for predicting the low-cycle fatigue life.
    Uniaxial plastic cycling tests were performed on 21/4Cr-1Mo steel to investigate the correspondence between the cyclic stress-strain curve and the hysteresis loop, and also to determine what mathematical model should be used for analysis of deformation at stress reversal.
    Furthermore, a cyclic in-plane bending test was performed on a flat plate to clarify the validity of the cyclic stress-strain curve-based theoretical analysis.
    The results obtained are as follows:
    (1) The cyclic stress-strain curve corresponds nearly to the ascending curve of hysteresis loop scaled by a factor of 1/2 for both stress and strain. Therefore, the cyclic stress-strain curve can be determined from the shape of hysteresis loop, for simplicity.
    (2) To perform the elastic-plastic deformation analysis using the cyclic stress-strain curve is both practical and effective for predicting the cyclic elastic-plastic deformation of structures at the stage of advanced cycles. And Masing model can serve as a suitable mathematical model for such a deformation analysis.
  • 池本 喜和, 清水 茂樹, 加納 厳, 鵜戸口 英善
    1983 年 32 巻 357 号 p. 615-619
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper describes the test results on strain concentration behaviour of type 304 stainless steel and 21/4Cr-1Mo steel. Type 304 stainless steel was tested at 600°C under cyclic displacement control and cyclic load control conditions, and 21/4Cr-1Mo steel was tested at 500°C under static creep condition. An improved fine grating method was developed for this study utilizing photo spots in the indentations made by Vicker's hardness tester. The results of stain measurements were compared with the predictions by the equation given in ASME Code Case N-47 and the structural design guide for Japanese fast breader reactor. The equation was proved to give a conservative prediction.
  • 田中 千秋, 大場 敏夫
    1983 年 32 巻 357 号 p. 620-624
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    A series of studies have been conducted on the effect of retightening (reloading) on stress relaxation behavior of high temperature bolts used in steam turbines.
    The present paper describes the results of reloading stress relaxation tests made after relaxed to various specific values of residual stress for 19Cr-9Ni-1.4Mo-1.4W-Nb bolting steel at the test temperature of 650°C. Most of the repeated loadings on the specimens were brought up to rupture.
    Logarithmic relations between the testing time at each cycle and the number of loading were analyzed numerically by taking the specific value of residual stress as a parameter. The results confirmed the previous empirical equation. As for rupture behavior, the following three terms, the number of loadings, the accumulated testing time, and the accumulated plastic strain, were expressed by power functions of the specific value of residual stress. From these equations obtained for reloading stress relaxation behavior and rupture, the design curves of retightening characteristics of bolts were presented.
  • 財前 孝, 乙黒 靖男, 青木 司郎, 鈴木 克巳, 板東 誠志郎
    1983 年 32 巻 357 号 p. 625-629
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to improve the high temperature properties of austenitic stainless steel weld metals, it is important to clarify the mechanism of formation and growth of brittle structures as well as the relation between brittle structure and fractograph of the creep ruptured specimens.
    The microstructure and the fractograph were determined by transmission and scanning electron microscopies on Tp 308 and Tp 308-V stainless steel weld metals made by GTAW. and SAW. methods. The results obtained are summarized as follows.
    (1) In the early stage of the creep process, dislocations are multiplied in austenite and locked by fine precipitates formed in austenite. Besides, the precipitates formed in δ ferrite grow up to 0.05μ diameter.
    (2) The formation of cell structure in austenite and the growth of precipitates in δ ferrite proceed during the creep process. These microscopic changes are affected by dissolution of the fine precipitates formed in austenite and their reprecipitation in δ ferrite. The addition of V restrains such dissolution and reprecipitation. These effects of V improve the creep rupture properties of Tp 308 stainless steel weld metals.
    (3) Fractograph of GTAW. weld metal of Tp 308V consists of dimple patterns which have similar forms and sizes with δ ferrite network. In the case of submerged arc weld metal of Tp 308V, the dimple patterns are found to be formed by inclusion and δ ferrite network on the fractograph. Both of the elongated dimple patterns formed by precipitated δ ferrite and the small dimple patterns (clearly distinguishable from the elongated one) which have similar forms and sizes with small cell structure in austenite are observed on GTAW weld metal of Tp 308.
  • 佐藤 恭, 車地 隆治, 木村 征二
    1983 年 32 巻 357 号 p. 630-634
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of heat treatment on the creep crack growth properties of 21/4Cr-1Mo steel was determined and then compared with the creep crack behaviour of actual weld joints. The results obtained are summarized as follows:
    (1) Creep crack growth properties are remarkably changed by heat treatment.
    (2) The creep crack growth rate increased with decreasing ductility, in the following order. Simulated HAZ>Water Quenched>Normalized-tempered>Annealed.
    (3) The J-da/dt curve on a high ductility condition is different from that on a low ductility condition even for the same steel.
    (4) Creep cracks advanced in the coarse grain heat affected zone in actual weld joints of 1Cr-1/2Mo steel. Creep crack resistance is improved by reduction of hardness due to stress relieving.
  • 大谷 隆一, 中山 忍
    1983 年 32 巻 357 号 p. 635-639
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    It is expected from the previous researches that the growth of many distributed cracks from the initiation to the size of several grains is the main process of creep fracture in heat-resisting alloys. Such a study on intergranular microcrack growth behaviors is important to clarify the characteristics of creep fracture.
    In this study, a continuous observation of intergranular microcrack growth at the surface of smooth specimens of 304 stainless steel was made during creep tests at 650°C in air and in vacuum. It was found that the effect of environment was different depending upon the stress value. That is, at high stress, the rupture time was shortened by intergranular oxidation, and on the contrary at low stress, it was lengthened by the formed oxide film which has protective and restorative actions. Also it was shown that the microcrack growth behaviors in creep were explainable on the basis of Weibull distribution of crack length.
  • 金澤 健二, 山口 弘二, 鈴木 直之, 佐藤 守夫, 金尾 正雄
    1983 年 32 巻 357 号 p. 640-644
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Stepwise S-N curves have been obtained at 500°C under rotating bending fatigue tests for the notched specimens of a low alloy steel SCM 435. The behavior of crack propagation under such fatigue conditions was examined, and the reason why such stepwise S-N curves appear and the effect of oxide formed at crack surface on the crack propagation were discusseed. The conclusions obtained were as follows:
    (1) On the fracture surface failed at the longer life side in the stepwise S-N curve, a certain region from the root of notch, designated as A region, was covered with thick oxide layer.
    (2) In the A region, a crack propagated with a very slow rate and the propagation rate scarcely depended on the crack length.
    (3) By examining the change in compliance under rotating bending conditions, it was clarified that the crack opening level was increased by the oxide formed on the crack surface. It is considered that with increasing the crack opening level the effective stress intensity factor range decreases and then the crack propagation rate decreases.
    (4) The stepwise change seems to occur at the boundary where the crack propagation rate slows down by the oxide formation.
  • 岡崎 正和, 白岩 不二男, 服部 一郎, 小泉 堯
    1983 年 32 巻 357 号 p. 645-650
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of strain wave shape on the propagation of strain-controlled low cycle fatigue cracks in Type SUS 304 stainless steel was investigated at 600 and 700°C. It was found that the rate of crack propagation in the cycle-dependent region was successfully correlated with a range of cyclic J-integral, regardless of strain wave shape, frequency and test temperature. It was also shown that the rate of crack propagation gradually increased from a cycle-dependent type to a time-dependent one as frequency decreased and slow-fast strain wave shape became obvious, and that the ratio of the range of creep J-intergral to that of total J-integral was an important factor in such a behavior. Furthermore, the fatigue crack initiation mechanism under strain with slow-fast strain wave shape was studied and it was shown that grain boundary sliding took an important role in it.
  • 岡田 友信, 堀川 武, 中村 宏, 恒成 利康, 武 浩司
    1983 年 32 巻 357 号 p. 651-656
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to establish the fatigue life prediction method for gas turbine blades, the fatigue tests are being conducted under the intermittent strain waveform which is composed of cycling of a large pulsating strain and superposed small strain cycling. In this paper, the results of fatigue tests on Inconel 713 LC under constant amplitude strain cycling, tension hold strain cycling and intermittent strain cycling at 600°C were given.
    The fatigue lives observed under the intermittent strain cycling were compared with those predicted by using the linear cumulative damage concept, and the following conclusions were obtained;
    (1) The observed failure lives under the intermittent strain cycling were shorter than the predicted ones using the linear cumulative damage rule based on the failure life curve under a constant amplitude strain cycling.
    (2) The observed crack initiation lives were in good agreement with those predicted by using the linear cumulative damage rule based on the crack initiation life curves under a constant amplitude and a tension hold strain cycling.
    (3) The crack propagation rate under the superposed small strain cycling was accelerated by the intermittent strain. When this effect of acceleration was taken into account to the fatigue life prediction, the predicted failure lives were in very good agreement with the observed failure lives under the intermittent strain cycling.
  • 桑原 和夫, 新田 明人, 北村 隆行
    1983 年 32 巻 357 号 p. 657-661
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate the characteristics of low cycle fatigue strength of a forged Ni-base superalloy IN 718 at elevated temperatures, strain-controlled fatigue tests were carried out on the smooth specimens and load-controlled fatigue crack propagation tests on the notched specimens. As a result, the failure life for the smooth specimen was found to be sensitive to the fracture mode and to decrease by changing from transgranular to intergranular fracture. It was also found that the failure life was independent of the type of straining in compression. The crack propagation rate in the intergranular fracture mode as well as in the transgranular fracture mode was correlated well with the stress intensity factor, which implied the creep fracture under a small scale creep condition.
  • 北川 正樹, 田村 敬二郎, 大友 暁
    1983 年 32 巻 357 号 p. 662-666
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The materials used in high temperature equipments are often subjected to the cyclic straining at the temperatures where fracture is often controlled by time dependent phenonena. The cyclic fracture at such high temperatures sometimes cannot be evaluated by the conventional creep or creep-fatigue fracture criteria. Therefore, a new fracture criterion utilizing the static and cyclic creep rupture time and static creep rupture ductility is proposed. In the criterion, fracture is considered to occur when the sum of the ductility exhaustion damage (which is proportional to the unidirectionally accumulated strain) and the creep damage (determined by time devided by cyclic creep rupture time) reaches a constant value.
    The criterion was successfully applied to the life prediction of the inscale fracture model of a high temperature heat exchanger made of Inconel 617 alloy. Furthermore, the strain rate dependency of cyclic life under various saw tooth waves was proved to be explainable by the same criterion if the local strain behavior was examined.
  • 服部 博, 北川 正樹, 大友 暁
    1983 年 32 巻 357 号 p. 667-671
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to study the effects of vacuum environment on high temperature low-cycle fatigue properties of Inconel 617, a set of strain controlled fatigue tests were carried out at 1000°C in air and vacuum environments.
    The fatigued specimens were metallographically examined by means of optical and scanning electron microscopies and electron probe microanalysis.
    The following conclusions were obtained:
    (1) The low-cycle fatigue life decreased as follows; in air<in poor vacuum (≅1.3Pa)<in vacuum (≅2×10-2Pa).
    (2) The difference of fatigue lives in air and in vacuum environments tended to become smaller for the specimen with coarser grains.
    (3) The environmental dependence of fatigue life can be explained based on the property of oxide scale, decarburization and internal oxidation behaviors, and the crack propagation rate.
  • 恒成 利康, 堀川 武, 岡田 友信, 武 浩司, 宮下 卓也
    1983 年 32 巻 357 号 p. 672-677
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effects of frequency and temperature- and strain-waveform on thermal fatigue strength were examined by conducting out-of-phase and in-phase thermal fatigue tests with three kinds of temperature-waveforms (fast heating and fast cooling, slow heating and slow cooling, slow heating and fast cooling) under temperature cycling between 350-650°C and by isothermal low-cycle fatigue tests at 650°C under cyclic frequencies of 0.5∼0.039cpm. The following results were obtained.
    (1) The effect of frequency on fatigue life in out-of-phase thermal fatigue was as small as in isothermal low-cycle fatigue, whereas in in-phase thermal fatigue it was much greater and the fatigue life reduction was more remarkable in low frequency.
    (2) The effect of temperature-and strain-waveform on thermal fatigue life was still smaller than the effect of frequency on out-of-phase thermal fatigue life.
    (3) The fracture mode of out-of-phase thermal fatigue was the transgranular type even at the lowest frequency tested, but that of in-phase thermal fatigue changed to the intergranular type at low frequency.
    (4) Out-of-phase and in-phase thermal fatigue data obtained at the test condition of such an extremely low frequency as 0.039cpm were found to coincide well with ΔεPC-NPC andΔεCP-NCP relations, respectively.
  • 岩永 省吾, 榊原 雄二, 三由 武, 猿木 勝司
    1983 年 32 巻 357 号 p. 678-682
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    This paper describes that the difference between out-of-phase and in-phase thermal fatigue lives of gray cast iron results from the difference in maximum tensile stress between two phases, which is caused by the unsymmetry in the stress-strain relation of gray cast iron.
    Thermal fatigue tests were performed in the temperature range, 150∼500°C, in which the growth of cast iron was negligibly small, under strain controlled conditions. The results obtained in this study are summarized as follows;
    (1) The life of in-phase thermal fatigue, in which tensile stress appears at the high temperature side, was about 30 times longer than the life of out-of-phase thermal fatigue, in which compressive stress appears at the high temperature side.
    (2) In the hysteresis loop of the first cycle, the maximum tensile stress in in-phase thermal fatigue was smaller than that in out-of-phase thermal fatigue. This fact is considered to result from that the unsymmetry of the stress-strain relation of gray cast iron, in tensile and compressive sides, is emphasized further by the disparity in temperature at which the maximum tensile stress appears.
    (3) The ratio of this tensile stress to tensile strength at the maximum temperature in in-phase, was also smaller than the ratio at the minimum temperature in out-of-phase. Therefore, the former life was longer than the latter life. And, after Nf/2 strain cycles, this tendency became more remarkable.
  • 中山 淳, 阿部 弘
    1983 年 32 巻 357 号 p. 683-689
    発行日: 1983/06/15
    公開日: 2009/06/03
    ジャーナル フリー
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