Journal of the Society of Materials Science, Japan

Fracture Mechanisms of Fretting Fatigue

Yoshiharu MUTOH

1997 Volume 46 Issue 11 Pages 1233-1241
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1233

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Effect of Stress Ratio on Fatigue Strength of Micro Pulse Induction Hardened Steel with Very Thin Case-Hardened Depth

Takeshi HORIKAWA, Hiroshi NAKAMURA, Masahiko KAWAMURA, Kazuhiro KAWASA ...

1997 Volume 46 Issue 11 Pages 1242-1247
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1242

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A new super rapid heating induction hardening technique has superior properties, such as very short heat treatment time, accurate case-hardened depth control and less deformation of hardened parts. Therefore, these properties have been useful for the surface improvement of machine parts.
In this paper, in order to investigate the influence of stress ratio on the fatigue strength of the induction hardened JIS S45C steel with very thin effective case-hardened depth (ECD) of 0.5mm, cyclic uniaxial loading fatigue tests have been conducted at four different stress ratios (R=-1.0-0.1) by using the notched round-bar specimens. Furthermore, the fatigue strength was discussed by fracture mechanics.
The results obtained are summarized as follows: (1) As stress ratio increases from R=-1.0 to 0, the stress range of the “fish-eye” type failure decreased. And, no “fish-eye” appeared under R=0.1. (2) The center of the “fish-eye” was located in accordance with the all case-hardened depth. Either non-metallic inclusion or facet exists at the center of “fish-eye”. (3) In the case of the fatigue crack initiation and propagation from the interior, the fatigue strength was predicted by using the threshold stress intensity factor ΔK_th. (4) In the case of the fatigue crack from notched root surface, the attenuation of residual stress under cyclic stress was considered experimentally. Consequently, the fatigue strength was predicted by the same method.

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Fatigue Crack Propagation in Circumferentially Pre-Cracked Steel Bars under Torsional and Axial Loadings

Keisuke TANAKA, Yoshiaki AKINIWA, Hirofumi NAKAMURA, Atsushi TERADA

1997 Volume 46 Issue 11 Pages 1248-1254
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1248

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The propagation behaviour of a circumferential fatigue crack in a cylindrical bar of medium carbon steel was studied under various combinations of cyclic torsional and axial loadings. The fatigue fracture surface was macroscopically flat under the conditions of excessive plasticity, and the J integral was applied to fatigue crack propagation under mixed mode loading. The propagation rate of fatigue cracks was expressed as a power function of the J integral range for both single and mixed mode cases. When compared at the same J intergal range, the propagation rate was highest for the mode I case and the lowest for the mode III case. The simple addition of the propagation rates of mode I and III gives the lower bound of the propagation rate under mixed mode loading. Striations were observed on the fatigue fracture surface made under mixed mode loading, and their spacing was equal to the crack propagation rate as in the case of mode I loading.

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Effect of Compressive Stress on Fatigue Crack Propagation in Polymers

Tetsuro SHIRAISHI, Hiroyuki OGIYAMA, Hitoshi TSUKUDA

1997 Volume 46 Issue 11 Pages 1255-1260
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1255

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The effects of negative stress ratio and single compressive overload on the fatigue crack propagation rate were investigated in polyvinyl chloride (PVC), polymethyl methacrylate (PMMA) and polyamide (PA). The fatigue crack closure behavior and fracture surface appearance were also examined. The fatigue crack propagation rate, da/dN, was found to increase with decreasing stress ratio in the relationship of da/dN versus the maximum stress intensity factor, K_max, for all polymers tested. This result implies that the compressive stress range in the cyclic loading causes the acceleration of fatigue crack propagation. The crack opening stress level decreased with decreasing stress ratio, and the fatigue crack propagation rate was found to be dominated by the effective stress intensity factor range, ΔK_eff. These facts suggest that such an acceleration for these polymers can be explained on the basis of the plasticity-induced crack closure concept just as for metals. On the other hand, the fatigue crack propagation rate was not affected appreciably by single compressive overload in this experiment.

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Propagation of Short Fatigue Cracks in Notched Specimens of Intermetallic Compound TiAl

Yoshiaki AKINIWA, Keisuke TANAKA, Hidehiko KIMURA, Makoto KOGOSHI

1997 Volume 46 Issue 11 Pages 1261-1267
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1261

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Single-edge-notched specimens of an intermetallic compound TiAl were fatigued under cyclic axial tension compression. The effect of microstructure on the propagation behavior of short fatigue cracks formed at the notch root was investigated. The crack length was measured with the AC potential method and the development of crack closure with crack extension was measured through the compliance method. The crack path is tortuous in lamellagrains, while straight in gamma-grains. When compared at the same non-propagating crack length, the crack opening stress intensity factor at the threshold increases with increasing lamella volume fraction. The relation between the crack propagation rate and the effective stress intensity range for short cracks was identical to that for long cracks. The resistance-curve method was used to predict the fatigue strength of notched specimens. The predicted values of the fatigue limits for crack initiation and for fracture, and the non-propagating crack length agreed well with the experimental results.

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Influence of Microstructure on Fatigue Fracture Characteristics of Al₂O₃

Mitsuo KIDO, Takuji OKABE, Hitoshi HASEGAWA

1997 Volume 46 Issue 11 Pages 1268-1273
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1268

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In order to improve the fatigue fracture characteristics of Al₂O₃, the fracture behavior of two kinds of Al₂O₃, whose microstructure was controlled by sintering additives, was investigated under static and cyclic loading. It was observed that there was a significant difference in fracture behavior between the fine equiaxial grained Al₂O₃ (Material M) and the coarse columnar grained one (Material SC). The examination of fatigue lifetime showed that the fatigue strength of Material SC was higher than that of Material M, but simultaneously a significant decrease by cyclic loading. The crack propagation rate da/dt of Material M made no difference between in air and in water, but that of Material SC accelerated in water. According to the results of an energy dispersive X-ray spectroscopy (EDX) analysis on the fracture surface of Material SC, it was found that the sintering additive components of Si and Ca decreased markedly in SCG region under cyclic loading in water, and it was expected that hydration reaction on the glass phase of grain boundary occurred actively by water. Consequently, the reason why the fatigue strength of Material SC decreased under cyclic loading in water was considered to the significant promotion of stress corrosion cracking at the crack tip which is caused by marked decrease of particle bridging effect (i.e., increase in K_Itip).

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Effect of Grain Size on High-Temperature Strength of Fast Reactor Spec. SUS316

Yukio TAKAHASHI, Shingo DATE, Takanori NAKAZAWA

1997 Volume 46 Issue 11 Pages 1274-1279
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1274

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Low-carbon/medium nitrogen 316 stainless steel called 316FR is a principal candidate for the structural material of a demonstration fast reactor plant. It is thus important to understand various effects on high-temperature strength of this steel. Especially the effect of grain size is important because the material with coarse grains will be used for thick components as well as weldment heat-affected zones. Various kinds of strength tests, including tensile, creep, fatigue and creep-fatigue tests, were conducted and the effect of grain size was investigated for both 316FR and 316 stainless steel with conventional chemical composition. 316FR showed considerably better properties than the conventional 316 with regard to creep and creep-fatigue strength. It was also found that the material with coarser grains have inferior characteristics in tensile, creep, fatigue and creep-fatigue tests. The applicability of Petch's equation was comformed for tensile and creep strengths of 316FR. A creep-fatigue life estimation method incorporating the grain size effect was proposed for 316FR.

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Influence of Microstructure and Notch on Low-Cycle Fatigue Behavior of Ti-6Al-4V Alloy at Elevated Temperature

Kazuaki SHIOZAWA, Seiichi NISHINO, Feng HONG

1997 Volume 46 Issue 11 Pages 1280-1285
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1280

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The influences of microstructure and notch on the low-cycle fatigue behavior of Ti-6Al-4V alloy at elevated temperature were studied. Three kinds of microstructures in Ti-6Al-4V alloy were prepared under different heat treatment conditions; eqiaxed α structure, lenticular α structure and bimodal (mixed structure of equiaxed α and lenticular α) structure. Low-cycle fatigue tests were performed at 773K in air under a stress controlled triangular wave form for the smooth and circumferentially notched specimens. The following conclusions were obtained.
(1) The low-cycle fatigue strength of the smooth specimen depended upon the microstructure. The highest was the bimodal structure and the lowest the lenticular α structure. However, the difference in low-cycle fatigue life among the specimens with different microstructures was not observed for the notched specimens with stress concentration factors of 2.5 and 6.0.
(2) The crack initiation of the smooth specimen was affected by the microstructure, but for the notched specimen the crack initiation occurred at the stress concentrated region and the fatigue life did not depend on the microstructure.
(3) The crack initiation lifetime of the notched specimen was predicted from the stress distribution around notch root obtained from the finite element method.

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Impact Tensile Properties of Nine Per Cent Nickel Steel

Shinji YOSHIE, Carlo ALBERTINI, Yukio MENTANI

1997 Volume 46 Issue 11 Pages 1286-1292
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1286

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Clarifying material dynamic behavior is of the highest priority for safety evaluation of any structure under an impact problem. Grasping the strain rate dependence of material is necessary for the evaluation of structural integrity. To derive the strain rate dependence, the impact tensile tests should be done in a way that strain rate could be maintained constant. To realize this, two kinds of testing devices have been developed in JRC (Joint Research Centre), Ispra. One is the hydro-pneumatic machine for a medium strain rate range from 0.1 to 100s^-1 and the other is the Modified Hopkinson bar device for a high strain rate range from 100 to 5000s^-1.
In the present study, for nine per cent nickel (9Ni) steel used for LNG (Liquefied Natural Gas) structure, the impact tensile tests were performed at strain rates up to the order of 1000s^-1, and the experimental results obtained are compared with those of carbon steel. The current tests revealed that 9Ni steel could have 50% more safety margin of strain energy even at a strain rate in the order of 1000s^-1 than that for carbon steel.

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Friction and Wear Properties of N⁺ ion-Implanted Silicon Nitride

Tsuneshichi TANAKA, Hideaki NAKAYAMA, Hikaru SEKIYA, Kohei SEKINE, Kaz ...

1997 Volume 46 Issue 11 Pages 1293-1299
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1293

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In order to investigate the effect of surface modification by ion implatation on friction and wear properties of sintered silicon nitride, a series of ball on disc type friction and wear tests was carried out on the non-implanted and ion-implanted silicon nitride. Ion implatation changes the friction and wear properties of silicon nitride depending on the dose of ion implantation. The ion-implanted silicon nitride with low dose (1×10¹⁷ions/cm²) shows slightly low friction coefficient accompanying the oscillation of the coefficient, in comparison with the non-implanted silicon nitride. Also the ion-implanted silicon nitride with low dose shows low wear resistance; the wear volume is greater than that of non-implanted silicon nitride. This suggests that the wear progresses in a weak wear resistance layer, i.e., the irradiation damaged layer. On the other hand, the ion-implanted silicon nitride with high dose (2×10¹⁷ions/cm²) shows extremely low friction coefficient during the early stage of rotation cycles, and in this stage the wear scarcely occurs.

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Thermal Stress and Stress Intensity Factor Considering Temperature Dependent Material Properties

A Circular Disk under Constant Heat Flux

Sawao HONDA, Toshifumi TAKAHASHI, Syouji MOROOKA, Shaowei ZHANG, Tadah ...

1997 Volume 46 Issue 11 Pages 1300-1305
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1300

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An infrared radiation heating method was proposed previously as a new technique for estimating thermal shock parameters directly from electrical power charge. The method uses a thin-circular disk heated by infrared rays at the central area with a constant heat flux. In this report, temperature and stress distributions in the disk are analyzed numerically considering the temperature-dependent material properties of alumina and float glass, namely, temperature-dependent thermal conductivity and thermal diffusivity for the temperature distribution and temperature-dependent thermal expansion for the stress distribution. Furthermore, stress intensity factors are analyzed for a disk with an edge crack subjected to a constant heat flux. These results show that the temperature dependence of material properties has siginificant effects on the temperature and stress distributions.

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Unified Treatment of Analytical Solutions for Uniform Heat Flow Problems of Isotropic Elastic Body with Hole of Arbitrary Shape and Their Numerical Examples

Kazuhisa FUJIKAWA, Ken-ichi HIRASHIMA

1997 Volume 46 Issue 11 Pages 1306-1311
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1306

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Thermal stress and displacement analysis as well as thermal stress intensity facters (TSIF) are given for the cases of an infinite plate (medium) having a free hole or a rigid inclusion of arbitrary shape under steady state heat flow from infinity. The hole whose surface is insulated or fixed at elevated temperature is also considered. Unified treatment of the analytical solutions for the above cases is obtained by use of the power series type of mapping function and complex variable method. Several numerical results are shown by graphical representation.

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Scattering of Plane Wave by an Elastic Fiber with Partially Debonded Interface

Boundary Element Analysis for Shear Wave Polarized Parallel with Fiber

Shiro BIWA, Harunori MIYAMURA, Toshinobu SHIBATA

1997 Volume 46 Issue 11 Pages 1312-1318
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1312

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Scattering of transverse elastic wave by an elastic fiber embedded in an infinite matrix with partially debonded interface is studied for time-harmonic steady cases by the boundary element method. The fiber is presently assumed to be of a right cylindrical shape, and the incident wave polarized parallel with the fiber axis and propagating in the plane normal to the fiber. In this circumstance the problem to be analyzed is two-dimensional and the governing equations reduce to a scalar Helmholtz equation for anti-plane displacements. Two kinds of boundary conditions are employed to describe the partially debonded fiber-matrix interface. In the first case, both the stress and the displacement are assumed to be continuous across certain parts of the interface, while on the rest of the interface the stress is supposed to vanish to simulate partial separation of the interface. In the second case, the notion of equivalent spring is introduced to take into account the presence of interface phase, thus resulting in the analysis of the case where the fiber is bonded to the matrix via an equivalent spring on partial areas of the interface while it is debonded on the rest. As an illustrative example, the total and differential scattering cross sections are computed for a circular cylindrical silicon-carbide fiber in a titanium alloy matrix for various frequencies. The influence of the extent of interface debonding as well as its orientation relative to the incident plane wave on the scattering behavior is discussed in detail.

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Change of Solubility Limit of Pb in Al by High-Pressure Treatments

Iwao KONDO, Masafumi SENOO, Yutaka TAKAHASHI, Shigeo KOTAKE, Akihito M ...

1997 Volume 46 Issue 11 Pages 1319-1322
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1319

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The possibility of changing the increment of solid solubility was investigated in Pb-added Al dilute alloy under the pressure of 5.4GPa. The high-pressure treated specimens were analyzed with X-ray diffraction, optical microscopic and transmission electron microscopic techniques. Their material properties such as density, hardness, elastic modulus and electric resistivity were also measured. A noticeable increase in solubility was not observed contrary to a thermodynamical predication.

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Piezoelectric Behavior of Wood Treated with Liquid Ammonia

Youki SUZUKI, Hironori TANIUCHI, Ryohei TANAKA, Nobuyuki HIRAI

1997 Volume 46 Issue 11 Pages 1323-1328
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1323

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The effects of wood treated with liquid ammonia on piezoelectric, dielectric and elastic relaxation were studied by using x-ray diffraction and measuring the piezoelectric, dielectric and elastic constants at the frequencies of 10, 30 and 100Hz. The relative crystallinity of wood after treatment was improved, so that the intensity of diffraction increased remarkably and the peaks appeared at about 20 and 12 degree.
The piezoelectric relaxation of shinanoki showed that the real part of piezoelectric constant d decreased with increasing temperature against control, but that of hinoki was different from shinanoki. It was supposed that the crystallinity of hinoki was not improved, because the micro-structure of hinoki was more complicated than that of shinanoki so that liquid ammonia was not effective enough to permeate into cell wall.
The piezoelectric relaxation was calculated using the two-phase system model, which consists of piezoelectric and non-piezoelectric phases. The piezoelectric dispersion of the piezoelectric phase appeared at the same temperature as the observed piezoelectric dispersion, and the dispersions of local coefficients L_T and L_E appeared at the same temperature as the observed dielectric and elastic dispersions. The piezoelectric relaxation existed in the piezoelectric phase and a part of non-piezoelectric phase; ie. piezoelectric relaxation was not only in the crystalline region but also in the amorphous region, especially that of oriented molecules.

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A Study on Surface Quality in Laser Machining of GFRP for Printed Wiring Board

Temperature and Damage at Workpiece in Drilling

Toshiki HIROGAKI, Eiichi AOYAMA, Hisahiro INOUE, Tsutao KATAYAMA

1997 Volume 46 Issue 11 Pages 1329-1334
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1329

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This paper describes the relation between the temperature and the damage at the hole wall of GFRP for printed wiring board in laser drilling. First, the temperature is measured by a thermocouple at various positions on the drilled hole wall in laser drilling. Secondly, the width of damage is observed by an optical microscope and SEM after laser drilling. The temperature at thermal damage is clarified by comparing these results. Finally, the thermal transfer model paying attention to the thermal properties of glass fiber is proposed for the laser drilling. From these experimental and calculated results, the practical formula is derived in order to predict the damage width.

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Sensory and Emotional Characteristics of Wood

V: Temperature-Humidity Environment and Wood

Takeo HAISHI, Misato NORIMOTO

1997 Volume 46 Issue 11 Pages 1335-1341
Published: November 15, 1997
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.46.1335

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