材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
43 巻 , 494 号
選択された号の論文の20件中1~20を表示しています
  • 小若 正倫
    1994 年 43 巻 494 号 p. 1385-1386
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    A series of conferences are being organized from the viewpoint of continuation of science and technology by the corrosion and prevention committee of the Society of Materials Science, and this is one of the reports presented at a conference to point out the importance of development of new materials.
  • 津留 豊, 関谷 雅紀, 中村 淳一, 斉藤 明夫
    1994 年 43 巻 494 号 p. 1387-1392
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    A micro-electrode consisting of an Ag/AgCl reference electrode was prepared by using the electroplating method on a tungusten wire as a corrosion current sensor for the scanning vibrating electrode technique (SVET), and it was applied to measure the corrosion current profile over a hardfacing alloy after corrosion in 10-3M sodium chloride. A good correlation was observed between the pitting corrosion current profile and the surface morphology of the corroded specimen. The pitting corrosion of the specimen developed in a chromium depleted zone between beads of weld metal, and manganese sulphide inclusions were always found in the pits along the chromium depleted zone.
  • 山口 祐一郎, 野中 英正
    1994 年 43 巻 494 号 p. 1393-1399
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    The fracture behavior of carbon steel was examined by slow strain rate test (SSRT) and the fracture process was analyzed to determine the effect of hydrogen in soil environment. The results obtained are as follows:
    (1) In an overprotective environment, a crack initiated and grew on the external surface of specimen. After growing to a certain size, the crack coalesced with another newly formed crack to form a large crack and final failure occurred. The crack initiation sites were identified on the SEM photograph to be at the quasi-cleavage fracture surface.
    (2) In soil, a crack initiated when the load reached a maximum and the final failure occurred after it elongated to approximately 400μm. The elongation in air from a maximum load point is two or three times greater than that in soil.
    (3) The fracture toughness of the specimen, KIC, was calculated to be 62.2 MPa√m in this experimental condition.
    (4) Hydrogen influenced the mechanical properties such as fracture toughness and elongation, but its effect is considered to be small for non-precracked steel unless load is larger than a maximum value.
  • 井上 博之, 山川 宏二, 福田 望
    1994 年 43 巻 494 号 p. 1400-1404
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Corrosion potential fluctuation of SUS304 stainless steel during stress corrosion cracking (SCC) was observed in a 35 mass% MgCl2 (353K) solution. The potential fluctuation was measured against an Ag/AgCl reference electrode with a digital voltmeter at a sample frequency of 2.56Hz. During the propagation stage of SCC, a trapezoidal potential fluctuation was observed, whose amplitude and frequency were about 1mV and one or a few times each 3.6ks, respectively. When the experiment was carried out without loading, the trapezoidal potential fluctuation was not detected. The effect of solution temperature on the corrosion potential fluctuation was also examined. An amplitude and an occurrence frequency of the trapezoidal potential fluctuation decreased with a decrease in temperature. The critical temperature for the SCC in the chloride solution environment had been reported to be 323K. The trapezoidal potential fluctuation disappeared at the temperature lower than 333K. Therefore, it was estimated that the trapezoidal potential fluctuation was only generated during the propagation stage of SCC.
  • 井上 博之, 山川 宏二, 福田 望
    1994 年 43 巻 494 号 p. 1405-1409
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the previous paper, the trapezoidal potential fluctuation was observed during the propagation stage of stress corrosion cracking (SCC). However, it had not been examined whether this potential fluctuation had a direct relation to SCC phenomenon. In this paper, the source of the trapezoidal potential fluctuation was investigated. A 35 mass% MgCl2 (353K) solution was employed similarly to the previously reported experiment. Potential fluctuation was measured against an Ag/AgCl reference electrode with a digital voltmeter at a sample frequency of 2.56Hz. The correlation between the elongation rate of the specimen and the potential fluctuation was examined. If the trapezoidal potential fluctuation had a direct relation to the SCC phenomenon, the elongation rate and the potential fluctuation should have a negative correlation. However, these two values correlated positively. The potential fluctuation change by unloading during the experiment was measured. Even after unloading, the trapezoidal potential fluctuation generated continuously. The effect of solution stirring on the corrosion potential fluctuation was also examined. The trapezoidal potential fluctuation disappeared when the solution was stirred. It was estimated that the trapezoidal potential fluctuation was caused by a perturbation of the concentration of dissolved oxygen in the proximity of sample surface. Therefore, it was judged that the fluctuation was not directly related to the SCC phenomenon.
  • 内田 仁, 井上 尚三, 森本 一行, 小寺澤 啓司
    1994 年 43 巻 494 号 p. 1410-1415
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    The susceptibility to intergranular embrittlement and stress corrosion cracking (SCC) of cold-rolled commercially pure titanium in a CH3OH/0.4% HCl solution at room temperature was examined fractographically.
    The results obtained from stress-free exposure tests showed a very small weight loss. In the subsequent tensile tests in air, the mechanical properties deteriorated greatly due to intergranular embrittlement though there was less dependent on rolling reduction. The resulting appearance consisted of intergranular and ductile fracture of which the area fraction approximated to a constant value, independently of rolling reduction. The threshold stress to SCC occurrence did not exist essentially, and its potential range corresponded with the active region of anodic polarization diagram. The uneven general corrosion appeared when the potential was moved to the positive direction. The fracture mode changed from an intergranular into a transgranular fracture which was characterized by the fluted pattern. Here, the former are a fraction increased with increasing rolling reduction and the latter inversely disappeared.
  • 杉江 他曽宏, 小舟 正文, 藤井 知, 山本 忠弘
    1994 年 43 巻 494 号 p. 1416-1421
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    The stability of passivation films on SUS304 and SUS316 stainless steels used for the bath container of an electroless nickel plating bath was studied by immersion test and electrochemical polarization method.
    The stainless steel specimens which had been passivated in 32.5% HNO3 for 3h at 313K were simultaneously immersed in the plating bath with a SS41 steel specimen. The concentration of phosphonic acid that was formed by oxidation of phosphinic acid in the bath increased during the immersion with the metal turnover. When the concentration exceeded 2mol·dm-3 in the bath, steady nickel deposition did not occur on SS41 steel.
    The anodic polarization curves of the stainless steels in 1N H2SO4 solution were measured by immersing them in the plating bath after passivation in 32.5% HNO3. The passive current on the polarization curve increased with immersion time and the corrosion potential moved to the positive direction. After the immersion for 60h the SUS304 specimen did not reveal any passivation on the polarization curve, but the SUS316 specimen did it even after the immersion for 144h. This indicates that the passivation film formed on SUS316 in 32.5% HNO3 is more stable than that on SUS304. The concentrations of phosphonic and phosphinic acids seem to be most influencial on the stability and breakdown of passivation films on the stainless steels.
  • 舛形 剛, 藤原 和雄, 梶原 修三, 林 浩一, 高谷 泰之, 稲葉 光晴
    1994 年 43 巻 494 号 p. 1422-1426
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    A heat exchanger for vaporizing liquefied natural gas (LNG) is made of Al alloy tubes and the way of protecting the tubes from corrosion by sea-water is to form a sacrifical anode layer by thermal-spray coating of Al-2 mass% Zn on Al alloy tubes. But in some cases, damage is found in the lower part of heat exchangers which are exposed to low temperature and flowing sea-water.
    In order to understand the corrosion behavior of coated Al-Zn alloy in this environment, the influence of temperature and rotating speed on the polarization behavior was examined by a rotating disk method simulating the flowing sea-water.
    In the case of low temperature and high rotating speed, the limiting current density of oxygen diffusion increased on the cathodic polarization curve. The corrosion reaction on the coated Al-Zn alloy is controlled by the cathodic reaction. Therefore, the corrosion rate increased in this case.
    With the addition of suspended solids, the corrosion potential on the coated Al-Zn alloy shifted to the less noble direction, indicating the removed of passive-film on the coated Al-Zn alloy.
    Therefore, it is concluded that the corrosion damage in this environment is caused by a kind of erosion-corrosion and is accelerated with the addition of suspended solids, such as crushed shell.
  • 小林 俊郎, 山田 伸弥
    1994 年 43 巻 494 号 p. 1427-1436
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
  • 新田 誠司, 木村 雄二
    1994 年 43 巻 494 号 p. 1437-1443
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    By using LPD (Liquid Phase Deposition) method, SiO2 thin film can be formed in H2SiF6 aqueous solution below 50°C. However, in almost all cases, thin films formed by LPD method were on glass substrate. Therefore, in this study, problems concerning the SiO2 film formation process on SUS304 stainless steel substrate were examined by incorporating various electrochemical techniques. From the results of potential and current density measurements under coupling conditions with a Pt counter electrode, the importance of keeping SiO2 supersaturated state of solution and the need of pretreatment and cathodic protection of stainless steel substrate were recognized for preventing the corrosion damage of substrate from the severe environment of H2SiF6 aqueous solution.
    Then, the thin SiO2 film formation process was examined through microscopic observations by SEM and chemical analysis by EPMA. As a result, the progress in the deposition process was recognized with time. However, some defects were recognized in the deposited thin SiO2 film on SUS304 stainless steel substrate. These defects may strongly influence the corrosion resistance of SiO2 thin film coated steel. On the other hand, some acceleration in the thin film formation process was recognized when the deposition was conducted under a cathodically protecting condition at which an aluminum piece was used as a sacrificial anode. It may be brought about by the acceleration in anodic dissolution of aluminun piece and also by the pH increase with H2 gas generation in the electrochemical reaction.
  • 谷口 貞司, 蚊野 敏之, 中村 雅彦
    1994 年 43 巻 494 号 p. 1444-1450
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Cement powders was treated with a high-velocity pneumatic double-stage impactor and the process of becoming globular was quantitatively analyzed by using a shape factor in order to obtain the optimum operation condition of the impactor. The powders used were not only the one-component but also mufti-component ones, and the effect of constituent minerals on the modifying mechanism of the cement particles was investigated. The relationship between the fluctuating characteristics, including the shape change of treated powders, and the operation conditions was examined on the assumption that the coalescence and break-down of cement particles takes place competitively under a high-velocity pneumatic impact.
  • 清木 隆文, 鄭 教〓, アイダン オメル, 市川 康明
    1994 年 43 巻 494 号 p. 1451-1456
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Kinking in rocks is a well-known phenomenon particularly among structural geologists. It is commonly observed in thinly layered sedimentary rocks subjected to folding and metamorphic rocks with well pronounced schistosity, cleavage such as schist, phyllite, slate, etc. The authors got involved with this phenomenon when they tested wooden specimens to obtain their mechanical characteristics. The authors report their experimental results and observations in this article and discuss their implications in rock mechanics. Our conclusions are;
    (1) Kinking always initiates from either a material or imposed mechanical singularity and grows into a band in which the strain is localised.
    (2) The visible kinking develops after the peak strength is exceeded. The orientation of fibers within the band decreases as the straining continues. Furthermore, the length of kining fibers in the band of the wooden specimens grows as the strain increases, while those of the rock specimens are constant as the strain increases.
    (3) However, the global orientation of the kink band with respect to the loading direction remains almost constant throughout the deformation process, provided that the confining pressure is kept constant. The inclination of kink bands is different from that of shear fractures which is predicted from Mohr-Coulomb yield criterion under compression.
  • ソーダライムガラスによる実験的検証
    野島 武敏, 杉山 文子, 阪口 健一
    1994 年 43 巻 494 号 p. 1457-1462
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    The present paper aims to verify experimentally the author's previous analytical method on the static fatigue data of brittle materials with an initial crack. The experimental results obtained on a soda-lime glass showed very good agreement with the analysis as follows: (1) the newly defined “normalized time to failure”, (Tf)N=Tf/(W*)/∫1x0{[x0F(x0)]/[xF(x)]}ndx, is very useful to analyze the experimental data; the initial stress-intensity KIi-values for two kinds of specimens (single edge cracked 3 point bending and tensile specimens) with different crack length are well expressed by a unique function of the (Tf)N(Tf; the time to failure, W; the specimen width, x0; non-dimensional initial crack length, F; the specimen's geometry factor and n; a constant), (2) a sharp gap in KI at the Region II on ∈-KI diagram still appears in the KIi-Tf relation (or σa-Tf relation, σa; the applied stress) though it becomes a little gentle, and (3) the existence of the lowest value of KI (the threshold) is experimentally clarified and the Region 0 was found.
  • 小川 哲男, 新川 和夫, 高橋 清, 武部 博倫, 森永 健次
    1994 年 43 巻 494 号 p. 1463-1468
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Zirconia-nickel composite materials were fabricated by powder processing technique and pressureless sintering. A tensile testing machine with a scanning electron microscope was utilized to study the deformation and fracture behaviors of the materials. Tensile tests were performed on dumbbell type specimens in vacuum at temperatures up to 800°C. Stress-strain relationships were determined for the composites as functions of temperature and volume fraction of ZrO2. The result showed that both the tensile strength and elongation to fracture decreased as the test temperature increased. It was also found that the strength increased with increasing volume fraction of ZrO2 up to 50%. To understand such effects, the deformation and fracture behaviors were investigated from microscopic view points through in-situ observation of the specimen surface and the fracture surface examination.
  • 後藤 真宏, 皮籠石 紀雄, 西谷 弘信, 宮川 浩臣, 尾田 安司
    1994 年 43 巻 494 号 p. 1469-1474
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    In order to investigate the scatter characteristic of growth rate for small cracks, rotating bending fatigue tests of smooth specimens were carried out using a normalized 0.21% carbon steel. Fifteen specimens were fatigued at each stress range, and the growth rate of major cracks was calculated from the smoothed growth curve for all the specimens. The growth rate obtained was analyzed statistically. The results show that the growth rate for each crack length can be expressed by three- or two-parameter Weibull distribution. The CV, coefficient of variance, for crack growth rate distribution was calculated, and by using the CV the scatter characteristic of growth rate was investigated. Furthermore, the relation between the average growth rate calculated from the smoothed growth curve and the real growth rate determined from the raw growth data was studied, and the applicability of small crack growth law to the microstructurally small crack was discussed.
  • 菅田 淳, 城野 政弘, 吉村 哲
    1994 年 43 巻 494 号 p. 1475-1481
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Surface fatigue crack growth tests under constant amplitude loading were carried out on three different materials of a medium carbon steel, JIS S38C, namely quenched and tempered material, quenched material and induction surface hardened material. It was found that the crack opening stress at the surface of hardened material was higher than those of the other materials, and the fatigue crack growth resistance in terms of the stress intensity range of surface hardned material was superior to the other materials. These differences resulted from the surface residual stress and there found little difference among three materials in the relationship between fatigue crack resistance and the effective stress intensity range. The higher crack opening stress intensity factor of the surface hardned material, Kop, could be well estimated by considering the actual stress ratio at the fatigue crack tip, R', which is defined as R'=(Kmin+Kr)/(Kmax+Kr), where Kmax and Kmin are the maximum and minimum applied stress intensity factors and Kr is the stress intensity factor induced by residual stress.
  • 欠陥寸法の評価精度および周波数依存性の検討
    金 〓, 庄子 哲雄
    1994 年 43 巻 494 号 p. 1482-1488
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Aiming at nondestructive detection and size prediction of defects with high accuracy and resolution, an Induced Current Focusing Potential Drop (ICFPD) technique has been developed. This technique can be applied for determining the location and size of defects in components with not only simple shape such as plain surface but also more complex shape and geometry such as curved surface and dissimilar joint.
    This paper describes the basic principle of ICFPD and its probe development. In this ICFPD, current was induced in a conductive material by a straight induction wire, which is electrically isolated, placed on it. The benefits of this new technique compared with the conventional ACPD are:
    (1) Current is induced and focused only at an explorating region.
    (2) Applicable to defect detection by scanning the sensor probe in an explorating region.
    (3) Applicable to defect detection in a weld joint of austenitic stainless steel.
    As the results of the innovation in instrumentation and the improvement in evaluation procedure by use of suitable parameters, the existence of defects is clearly observed as the variation of potential drops, and the nondimensional parameter (Vc, max./Vavg.) has a direct correlation with crack depth. Especially, for the depth less than 5mm, the ICFPD shows higher sensitivity than the conventional ACPD at the frequencies of 3, 10 and 30kHz.
  • 黒瀬 雅詞, 津田 政明, 佐々木 敏彦, 広瀬 幸雄, 吉岡 靖夫
    1994 年 43 巻 494 号 p. 1489-1495
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    Recently, the accuracy of stress values by X-rays was highly improved. The reason seems to be the improvement of data processing by computer and equipment. However, it is sometimes difficult to determine the stress value with high accuracy when poor diffraction profiles with scattering noise and distorsion were measured. These profiles often depend largely on the experimental conditions. Thus, it is required to select the most suitable one by use of a certain parameter on the X-ray diffraction.
    On the other hand, fractal geometry is being introduced for an analysis of irregular time series. It may be applicable in the field of X-ray diffraction because the diffraction profile is a kind of irregular time series. So, it is attempted here to obtain a new interpretation about X-ray diffraction profile by the fractal analysis.
    In the present study, it was investigated first whether X-ray profile has the fractal characteristics or not. The result obtained showed clearly the fractal characteristics. The X-ray parameters were compared with the fractal dimension D for each experimental condition, and the condition of the minimum error on the experimental result was obtained. It seems possible to select a most suitable experimental condition by using the fractal dimension as a parameter.
  • 岩永 弘之, 沖 猛雄
    1994 年 43 巻 494 号 p. 1496-1501
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
    This study was intended to develop the alleviation countermeasures against hydrogen embrittlement of an austenitic stainless steel (SUS304). As the first step, the passivation treatment which is recommended to be used for prevention of crevice corrosion in “Method of pitting potential measurement for stainless steel” in JIS was adopted. Slow strain rate tension tests were carried out for the passivation treated specimens under the environment of hydrogen evolution immediately after the specimens were held for various time periods at hydrogen evolution potentials on the cathodic polarization curve which was obtained in 3%NaCl solution. The main results obtained are as follows.
    (1) The pitting initiation potential of the passivation treated specimen showed a more noble potential of 0.087V (vs. S.C.E.) than the untreated specimen. The passivity maintaining current also showed a stable state. Therefore, the passive state film which was formed on the specimen is considered stable.
    (2) The passivation treated specimen immersed for 90 minutes in 30%HNO3 solution at 60°C showed a larger change of mechanical properties, i.e., reduction in area and time to fracture, than the untreated specimen at cathodically charged potential under each setting condition.
    From the SEM observation of fracture surfaces, the fraction of brittle region in the treated specimen, characterized by transgranular fracture including quasi-cleavage fracture, decreased from that of the untreated specimen. The effect of passive state film was well recognized, and the hydrogen embrittlement behavior appeared alleviated.
  • 7. 生体用材料の疲労
    林 紘三郎
    1994 年 43 巻 494 号 p. 1502-1506
    発行日: 1994/11/15
    公開日: 2009/06/03
    ジャーナル フリー
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