Journal of the Society of Materials Science, Japan
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
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Volume 51, Issue 7
Displaying 1-17 of 17 articles from this issue
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  • Mechanism of Magnetic Domain Refinement on Grain-Oriented Silicon Steel by Laser Irradiation
    Hiroshi SUZUKI, Koichi AKITA, Hiroshi MISAWA, Muneyuki IMAFUKU
    2002 Volume 51 Issue 7 Pages 730-735
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.730
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    The residual stress distributions near the laser irradiation in a crystal grain of an electrical steel sheet were measured by X-ray stress measurement method for single crystal, in order to investigate the causes of the magnetic domain refinement which can apply to decrease the core loss. The specimen which has only one grain was machined from a grain-oriented silicon steel and the laser irradiation was applied on this specimen. The distribution of the residual stress and the half value width (H.V.W.) of diffraction profile, which indicate the level of the plastic strain, near the laser irradiation were measured and its magnetic domain was observed before and after the stress relieving annealing. Before annealing, the H.V.W. was increased near the laser irradiation because of the local plastic deformation occurred by the effect of the peening on laser irradiation and the process of melting, cooling and solidification after laser irradiation. Therefore the tensile residual stresses were concentrated near the laser irradiation. And then, the magnetic domain was refined more than before the laser irradiation. After annealing, the H.V.W. was constant at the initial value and the residual stress was relieved. And then the magnetic domain returned to its original width. Therefore, it was confirmed that the magnetic domain was refined due to the residual stress occurred by the laser irradiation.
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  • Effect of Polarization on Deformation and Fracture of Piezoelectric Ceramics
    Kaori SHIRAKIHARA, Keisuke TANAKA, Yoshiaki AKINIWA, Kenichi MIZUNO
    2002 Volume 51 Issue 7 Pages 736-742
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.736
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    Four-point bending tests were conducted with smooth specimens of poled and unploed lead zirconate titanate (PZT) ceramics with the tetragonal structure. The true stress-strain relations for tensile and compressive deformations were calculated from the relations of load against tensile and compressive surface strains under the Bernoulli's assumption of beam deformation. The relations showed nonlinearity and were different respectively depending on the poling conditions. The nonlinearity of the stress and strain relation comes from domain switching induced by external loading, and the degree of nonlinearity increased with the easiness of domain switching. The fracture strength in terms of the nominal and true stresses follows the Weibull distribution. The mean strength is the largest for NP specimen and is the lowest for PL specimen. The shape parameter takes a large value around 18 to 22 for PT and PS specimens, while it is the smallest around 7 to 8 for PL specimens. NP specimens take a value in between. Domain switching during loading will relieve local stress concentrations of defects within the material, thus increase the strength and the shape parameter. The change in intensity ratio of the 002 to 200 diffractions by X-rays can be used to assess the degree of domain switching caused by external straining.
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  • X-Ray Stress Measurement of Cu/TiN Films
    Tatsuya MATSUE, Takao HANABUSA, Yasukazu IKEUCHI
    2002 Volume 51 Issue 7 Pages 743-748
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.743
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    Residual stresses in a coating film will be influenced by undercoatings in a multi-layered film system. The present study investigates residual stresses as well as crystal textures in a two layer copper (Cu)/titanium nitride (TiN) film on a glass substrate. A TiN film was first deposited by arc ion plating on a glass substrate as an under layer. A Cu film was then deposited by RF sputtering on the TiN film deposited by arc ion plating. The crystal texture and residual stress in the deposited films were investigated by X-ray diffraction as a function of film thickness of each layer.
    Both the Cu film and the TiN film had a strong {111} orientation. The two-exposure method was then used to evaluate residual stresses in the Cu and the TiN films by measuring lattice strains in two directions determined by crystal orientation. The Cu layer had tensile residual stresses of 450-630MPa. These stresses increased with both the film thickness of the Cu layer and the TiN layer. The TiN layer had also in tensile residual stress of 230MPa. Although the texture of Cu and TiN films did not change by annealing at temperatures below 400°C, the residual stresses in Cu layer decreased with the annealing temperatures, whereas those in TiN layer increased.
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  • Mechanism of Decrease in Corrosion Resistance of Cr Plated Parts Due to Heat Treatment and Measures to Prevent Decrease
    Yuichi KOBAYASHI, Jun-ichi NAGASAWA, Toshihiko SASAKI, Yukio HIROSE
    2002 Volume 51 Issue 7 Pages 749-755
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.749
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    The mechanism of decrease in the corrosion resistance of Cr plated parts when they are subjected to a heating process and measures to prevent the decrease are studied. When the post finishing is performed after the Cr plating process, cracks in the Cr layer are closed as a result of plastic flow on the topmost surface layer. When the residual stress in the Cr layer becomes compressive due to the post finishing, the cracks are completely closed, resulting in a high corrosion resistance. The residual stress in the Cr layer changes from compressive to tensile following heat treatment. When the residual stress becomes tensile, the cracks in the Cr layer which were closed during the post finishing open once again, resulting in a decrease in the corrosion resistance. We speculated that the change of residual stress from compressive to tensile is caused by the shrinkage of the Cr layer due to heat treatment, and the difference in the coefficients of thermal expansion between the substrate (steel) and Cr layer, as well as the release of residual stress generated during processing. In order to prevent the decrease of corrosion resistance under heat treatment, it is effective to apply compressive stress, which exceeds the level of change in residual stress due to heat treatment, to the Cr layer during the post finishing, after the Cr plating process.
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  • Residual-Stress Distribution of Shot-Peened Steel Estimated by High-Energy X-Rays from Synchrotron Radiation Source
    Etsuya YANASE, Kouji NISHIO, Yukihiro KUSUMI, Kazuo ARAI, Kenji SUZUKI ...
    2002 Volume 51 Issue 7 Pages 756-763
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.756
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    This paper described a new nondestructive measurement of the in-depth distribution of residual stresses by using monochromatic high energy X-rays from synchrotron radiation source of SPring-8. The measurement was carried out by using the sin2ψ method with the Ψ-diffractometer. It was first proved to have a high accuracy in measuring the loading stress by four-point bending.
    The diffractions with five different penetration depths obtained by X-rays with three energy levels, 30, 60, and 72keV, were adapted to measure the residual stress below the surface of shot peened steels. The residual stress distribution measured by five penetration depths agreed well with the residual stress distribution determined by the conventional Cr-Kα radiation combined with the method of the successive removal of the surface layer by electropolishing. The compressive zone extended 150 and 300μm below the surface depending on the intensity of shot peening.
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  • Influence of Detector Misalignment on the Ω Assembly X-Ray Stress Measurement Using a Position Sensitive Proportional Counter as a Detector
    Toru GOTO, Yu GONG
    2002 Volume 51 Issue 7 Pages 764-770
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.764
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    Recently, the position sensitive proportional counter (PSPC) has been becoming popular as a detector for the X-ray stress measurement. However, little information is available in the literature regarding the effects of systematic errors such as specimen mis-setting, collimator misalignment and detector misalignment etc. on the stress measurement using the PSPC.
    In this paper, the detector misalignment is discussed using a model and a simulation method of the Ω assembly X-ray stress measurement. The stress errors Δσrd, Δσtd and Δσkd due to the translation rd in the direction of goniometer radius, the translation td in the direction of diffraction angle and the rotation kd, respectively, were calculated as the value of measured stress σx subtracted by specimen stress σ and intrinsic stress σc.
    It was found that Δσrd, Δσtd and Δσkd are expressed as a linear relation of rd, td and kd, respectively. The slope of the relation depends on the collimator dimensions, goniometer radius and specimen stress. However, the absolute value of Δσrd, Δσtd and Δσkd were found extremely small for the conditions examined. If the detector is misaligned under the combination of translations and rotation, the stress error is the sum of the errors due to translations and rotation. If the stress is measured under detector misalignment with specimen mis-setting, the stress error is the sum of the errors due to detector misalignment and specimen mis-setting. Under the detector misalignment with collimator misalignment, the stress error is the sum of the errors due to detector misalignment and collimator misalign-ment. It was concluded that the stress error due to detector misalignment is negligibly small when compared with those due to specimen mis-setting and collimator misalignment.
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  • Progress in the Instrumented Charpy Impact Test
    Toshiro KOBAYASHI
    2002 Volume 51 Issue 7 Pages 771-779
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.771
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  • Fracture and Deformation on (0001) and (1010) in Sapphire Single Crystals with Vickers Indenter
    Shinzo KOBAYASHI, Shinji MASUI, Sei MIURA
    2002 Volume 51 Issue 7 Pages 780-787
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.780
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    Abrasive wear on the contacting surface of machine elements proceeds via penetration or scratch of the sharp asperity tips or wear debris. In order to elucidate the mechanism of wear, it is firstly necessary to have knowledge on the microscopic deformations such as dislocations, minute cracks and slips induced by such penetrations. In the present study, indentation tests using a Vickers indenter were carried out on the (0001) and (1010) crystal faces of Sapphire (Al2O3) single crystals.
    The diagonal of an indenter was oriented in two ways: parallel and 45° against the [1010] direction on the (0001) face, and against the [0001] direction on the (1010) face respectively. The cleaving faces and directions of propagation of the cracks around an indent were estimated. In addition the shape and distributions of etch pits around an indent were examined.
    The results obtained are summarized as follows:
    (1) Radial cracks originate in four directions under comparative lower load of 5.0N, and in six directions under higher load of 10.0N on both of the (0001) and (1010) faces. Raptures that form connections with these cracks are also observed.
    (2) An average length of cracks on the (0001) is longer about 20% in 0° indentation than that in 45° indentation.
    (3) Cracks and edges of an indent are formed in a curved pattern due to the anisotropic crystal deformation.
    (4) Twinnings are observed on the (1010) in both 0° and 45° indentations.
    (5) Noticeable difference in size of indent was not confirmed in 0° between 45° indentation. An average length of the cracks on the (1010) is about 2.0 times as long as that on the (0001).
    (6) The area around an indent on the (1010) is corroded by etching in similar figure to individual etch pit.
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  • Multiaxial Plastic Behavior of Prestrained Mild Steel and Its Analysis by a Subsequent Yield Function of the Sixth Degree
    Takenobu TAKEDA, Zhongchun CHEN, Tomoki NAKAYAMA
    2002 Volume 51 Issue 7 Pages 788-794
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.788
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    The subsequent yield function previously proposed by one of the authors is modified by introducing the fourth rank tensor of anisotropic moduli. This yield function accounts for the effects of the third deviatoric stress invariant and anisotropy and the Bauschinger effect. Multiaxial loading tests are carried out on tubular specimens of mild steel subjected to various amounts of torsional prestrain. Two modes of loading are used to assess the theoretical predictions: one is the combined tension- torsion and the other is off-axis torsion by means of the combined loading of compression, internal pressure and torsion. The equi-strain loci and strain behavior are examined as a function of prestrain at three levels of offset strain ranging from 0.002% to 2.0%. In the tension-torsion stress field, the equi-strain locus specified by a 0.002% offset forms a nose in the prestress direction and flattens on the opposite side. The locus expands with increasing offset strain, so that both the sharpness of nose and the degree of flattening decrease. The deviation between the directions of the principal shear stress and principal shear strain increment is determined from the off-axis torsion test. It rises to a maximum value with a change in the principal shear stress direction and then decreases. The maximum deviation is larger when a smaller offset strain is used, and it increases as the prestrain becomes larger. Such behavioral characteristics can be expressed precisely by the constitutive equation derived from the proposed yield function, hardening law and associated flow rule.
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  • Effect of Microstructure on Fatigue Crack Propagation Behavior in Ultrafine-Grained Steel
    Hidehiko KIMURA, Yoshiaki AKINIWA, Keisuke TANAKA, Jun KONDO, Tadashi ...
    2002 Volume 51 Issue 7 Pages 795-800
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.795
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    Steel plates with surface layers having ultrafine-grained microstructure, called SUF steel, exhibit excellent crack arrestability against brittle crack propagation by forming shear-lips at the surface layers. Although SUF steels have been proven to possess superior fatigue properties as well, the mechanism of the improvement in fatigue properties is not fully understood. In this study, smooth specimens and single-edge-notched specimens were prepared from the ultrafine-grained surface layer and the medium-grained mid-thickness region in the LT and LS directions. The specimens were fatigued under cyclic axial tension compression at room temperature. The effects of the microstructures on the fatigue limits and crack propagation behavior were investigated.
    The crack propagatiom rate, when compared at the same stress intensity range, was the lowest in the ultrafinegrained LS specimen. The threshold value of the stress intensity range in the ultrafine-grained LS specimen was higher than that in the medium-grained LS specimen, indicating that the ultrafine-grained specimen exhibited not only higher fatigue limits but also superior crack arrestability against long fatigue cracks. The higher crack arrestabiliy in the ultrafine-grained spesimen is attributed to bifurcation of fatigue cracks.
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  • Atomic Force Microscopic Observation of Initiation and Early Propagation of Small Fatigue Cracks in Ultrafine-Grained Steel
    Hidehiko KIMURA, Yoshiaki AKINIWA, Keisuke TANAKA, Jun KONDO, Tadashi ...
    2002 Volume 51 Issue 7 Pages 801-807
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.801
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    Steel plates produced by an advanced thermo-mechanical control process have two regions: the ultrafinegrained surface layer with the average grain size of less than 2μm and the intermediate region with medium-sized grains. Smooth specimens made of ultrafine-grained and medium-grained regions were fatigued under cyclic axial tension compression at room temperature. The effect of the microstructure on the initiation and the early propagation of small fatigue cracks were investigated by observing the images of specimen surfaces replicated on plastic sheets by atomic force microscopy. In the medium-grained specimens, the fatigue cracks initiated from the simple slip lines. In the ultrafine-grained specimens, complex slip deformation in the shape of irregularities of the specimen surface was observed prior to the initiation of fatigue cracks. The fatigue cracks were nucleated at the grain boundary between the grains containing the complex slip deformation. The crack propagation rate in the ultrafine-grained specimens decreases because of the grain-boundary blocking and crack deflection in an early stage of the propagation.
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  • Initiation and Propagation of Fretting Fatigue Crack in the Very Long Fatigue Life
    Jin-Quan Xu, Satoru SHIRAI, Wei-Ming TAO, Yoshiharu MUTOH
    2002 Volume 51 Issue 7 Pages 808-813
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.808
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    In fretting fatigue, a fatigue crack initiated from the contact edge can be found even in the specimen which survives up to 107 cycles. This fact means that fretting fatigue fracture may occur if the specimen undergoes very long fatigue cycles (more than 107 cycles). To characterize the fatigue properties of very long life fretting fatigue, it is necessary to understand the effect of the singular stress field near the contact edge on the crack initiation and propagation. In this study, fretting fatigue tests below the fatigue limit (corresponding to 107 cycles) were carried out. The fatigue tests were interrupted at 107 cycles, and the fatigue cracks were observed by SEM. Numerical analysis by FEM was also carried out. It was found that the fatigue crack initiation at the contact edge could be evaluated by the stress intensity coefficient of the singular field, and the crack propagation/non-propagation could be estimated. by ΔKθmax in the direction of Δσθmax, with an introduction of an initial crack with the critical length over which the linear fracture mechanics can be applied.
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  • Relationship between Fractal Dimensions of AE Amplitude Distribution and Fracture Patterns of Fatigue-Loaded FRPP
    Sotoaki KIDA, Akihito SERIZAWA, Noriyuki TAKANO, Megumu SUZUKI, Takesh ...
    2002 Volume 51 Issue 7 Pages 814-820
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.814
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    The tensile test was conducted on the fatigue-damaged FRPP specimens, including fiber content in weight of 50% made by direct injection molding method. Fracture patterns were examined by the fractal dimensions from the AE amplitude distributions detected during the fracture process and the strain energy stored to fracture. The fracture patterns of FRPP specimens are mainly dominant at the fiber debonding from the AE frequency analysis obtainedduring the tensile test. The relationship between the normalized fractal dimensions of FRPP and the ratio of cyclicnumbers N/Nf shows the upper convex. It resembles the relationship between the standardized energy release rate at the fiber debonding and the fiber debonding angle in model composite specimen. The fracture patterns are also found on the relationship between the strain energy and N/Nf. These results are compared with those of the fatigue-damaged FRPA specimens.
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  • Impact Fracture of Ceramic Plates Using Extended Distinct Element Method
    Koichi KAIZU, Toshiro SAIKI, Shuji TOMINAGA, Kiyohiko IKEDA
    2002 Volume 51 Issue 7 Pages 821-825
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.821
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    This paper presents an impact fracture analysis of a ceramic plate by the extended distinct element method (EDEM). The EDEM model consists of springs, dampers and sliders between two elements in both the normal and tangential directions. This model has the continuity by introducing the pore-springs, which show the effect of the pore material between elements. The medium composed of the EDEM model becomes gradually discontinuous with the destruction of the pore-springs. The purpose of this study is to confirm usefulness of this method for the analysis of the impact fracture and to examine the effect of the impact velocity on the impact fracture behavior. From numerical results, it is shown that the impact velocity greatly influences in the mode of the impact fracture and the genera-tion of the crack is localized at the collision part with the increase in the impact velocity. It is also found the position of fracture is closely related to the position of the high equivalent stress.
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  • Effect of Pellet Geometry and Water Absorption on Strength of Long Jute Fiber Reinforced Polypropylene
    Kazuhiro SHIMA, Hironori MIZOGUCHI, Kazuya OKUBO, Toru FUJII, Tatsuya ...
    2002 Volume 51 Issue 7 Pages 826-831
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.826
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    Effect of the twisting direction, pellet fiber length and water absorption on the strength was investigated for an ecological jute fiber reinforced polypropylene (JFRP).
    High strength of JFRP is observed if jute fibers are well dispersed in the PP. It is necessary to pre-penetrate the matrix into the jute fiber bundle in producing the pellets for the dispersion of jute fibers, because the injection time should be reduced not to degrade the fiber strength at elevated temperature. For the pre-penetrating the matrix, Jute fibers should be twisted in opposite direction to the screw rotation at extruding the pellets. The interfacial failure is observed for any cases of the fiber lengths in pellet. However, the strength of JFRP has a maximum with respect to the fiber length. When the moderate fiber length encourages the ravels and dispersions of the fibers, high strength of the JFRP is obtained. A devised screw (CMH) is also effective for increasing the strength of JFRP, because it improves fiber dispersion.
    If the JFRP absorbs moisture under high humidity, the strength of it decreases remarkably. The microscopic failure mode, however, is independent of the water absorption, i.e. interfacial failure is observed at all testing conditions. The reduction of fiber strength dominates that of JFRP due to water absorption.
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  • Dispersion of Concentrated Alumina Aqueous Slurry
    Osamu TAKAGI, Kazuyuki YOGO, Masakuni OZAWA, Suguru SUZUKI
    2002 Volume 51 Issue 7 Pages 832-835
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.832
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    The particle dispersion in concentrated alumina aqueous slurry was investigated from colloidal vibration potential (CVP) and viscosity. In the present work, the CVPs of the slurry (40mass%) were measured by an ultra-sonic vibration method as a function of pH and the concentration of organic dispersants, and viscosities were measured with a rotating cylinder viscometer for the slullies containing 0.04-4mass% dispersant at pH 7. The CVP shifted to negative potential side with both increases in pH and the concentrain of dispersant in the range of 0.04-2mass%. The minimum viscosity appeared at with 2mass% dispersant. Moreover, it was found by an elemental analysis that the surface of alumina particles were saturated with dispersant molecules at about 2mass%. From the above mentioned, the CVP measurement thought to be effective in evaluating the particle dispersion in the concentrated alumina aqueous slurry.
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  • Materials Science Toward “Super-” and “Ultra-” High Temperature Technologies
    III: High Temperature Strength of Ni-Based Superalloys and Coatings for Advanced Gas Turbines
    Hiroshi HARADA, Masakazu OKAZAKI
    2002 Volume 51 Issue 7 Pages 836-842
    Published: July 15, 2002
    Released on J-STAGE: June 03, 2009
    DOIhttps://doi.org/10.2472/jsms.51.836
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