Journal of the Society of Materials Science, Japan

Diffraction-Plane Dependence of Elastic Constants of Silicon Nitride for X-Ray Stress Measurement

Keisuke TANAKA, Mitsuyoshi HATTORI, Hiroshi TANAKA

1995 Volume 44 Issue 504 Pages 1110-1114
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1110

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X-ray elastic constants of two kinds of silicon nitride, gas-pressure sintered (EC141) and pressureless sintered (SN1), were experimentally determined for ten different diffractions by using Kα radiations of Cu, Co, Fe, Cr and V. For the stress measurement with high precision, 323 reflection by Cu-Kα₁ radiation, 251 and 232 reflections by Fe-Kα radiation, and 411 reflection V-Kα radiation are recommended. The X-ray compliances, (1+ν)/E and ν/E (E=Young's modulus, ν=Poisson's ratio), change as a second power function of cos²φ (φ=angle between the diffraction plan normal and the c-axis of hexagonal crystal) for both kinds of silicon nitride.

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Diffraction Plane Dependence of Elastic Constants in Ferritic Steel in Neutron Diffraction Stress Measurement

Makoto HAYASHI, Masayuki ISHIWATA, Noriaki MINAKAWA, Satoru FUNAHASHI, ...

1995 Volume 44 Issue 504 Pages 1115-1120
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1115

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Neutron diffraction measurement have been made to investigate the diffraction plane dependence of elastic constants in ferritic steel. The measured diffraction planes were 110, 220, 112, 222 and 200. In the measurement a small tensile specimen was loaded in the tensile test rig specially degsined for a neutron diffractometer. The strains obtained for five diffraction planes increased almost in proportion to the applied stress up to 230MPa nearly equivalent to the yield stress. The mean elastic constants obtained were E=243GPa and ν=0.28 for 110, 220 and 112, 182GPa and 0.31 for softest 200, and 268GPa and 0.30 for stiffest 222, respectively. The bulk elastic constants, E=222GPa and ν=0.29, measured by the strain gauges almost agreed with the mean values for 110, 220 and 112. The Kroner elastic model is found to account for the diffraction plane dependence of Young's modulus and Poisson's ratio of the ferritic steel.

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Effects of Depositing Temperature and Film Thickness on Residual Stress of TiN Coated Materials

Tatsuya MATSUE, Takao HANABUSA, Yasukazu IKEUCHI

1995 Volume 44 Issue 504 Pages 1121-1126
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1121

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Large residual stress is formed in the coating of ceramic material deposited on a metal substrate because of difference in thermal expansion coefficient between the film and the substrate and of some other reasons. The residual stress greatly influences the mechanical properties of the film and the coated material. Therefore, the residual stress is one of the most important factors on evaluating the strength of coated materials.
In the present investigation, we studied the residual stress in TiN film deposited on a substrate of spring steel by a multi-arc method as a function of depositing temperature and film thickness. The residual stress in the substrate layer near the interface was also investigated.
The TiN film exhibited highly {111}-orientation, i.e., [111] of TiN crystals orients parallel to the surface normal of the substrate within ±10 degrees. The residual stress in the TiN film could be evaluated by the two-exposure method with getting the lattice strains for 222 diffraction at φ=0° and 70.5° determined by the relation of crystallographic orientation. The results revealed the compressive residual stress of -5.5--3.5GPa which is very large compared with the thermal residual stress due to the thermal strain mismatch between the film and the substrate. The residual stress value was greatly depended on the depositing temperature; it decreased with increasing temperature, and thickness of TiN film and increased with increasing film thickness. The residual stress in the substrate was compressive and below -30MPa probably due to the implantation of Ti ions into a shallow layer of the substrate.

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Estimation of Grinding Flaw Size of Ground Silicon Nitride Based on Fracture Mechanics

Yoshihisa SAKAIDA, Keisuke TANAKA, Kenji SUZUKI, Hiroshi KAWAMOTO

1995 Volume 44 Issue 504 Pages 1127-1132
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1127

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The surfaces of bending specimens of silicon nitride were ground in two different grinding directions with a diamond wheel. One was parallel and the other was perpendicular to the longitudinal direction of specimens. The Weibull distribution of the bending strength of ground specimens was compared to that of lapped specimens. The average fracture strength normal to the grinding direction fell by about 25% in comparison with the average strength of lapped specimens. The residual stress distribution near the ground surface was measured by the cosφ method of X-ray stress measurement. The stress state was biaxial. One of the pricipal directions of stresses was along the grinding direction. Both of the principal residual stresses, σ₁ and σ₂, were compressive and decreased exponentially with increasing the distance from the surface. The residual stress was diminished at about 30μm in depth. The increment of strength due to compressive residual stresses was determined by calculating the stress intensity factor of a semi-elliptical surface crack in the residual stress field. The size of grinding flaws degrading bending strength was estimated from the relation between the fracture strength and the surface crack size. The depth of grinding flaws parallel to the grinding direction ranged approximately from 40 to 70μm; the deepest point of flaws was out of the zone of compressive residual stresses.

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R-Curve Behavior for Stable Crack Growth from Indentation Cracks in Alumina

Kenji SUZUKI, Keisuke TANAKA, Yoshihisa SAKAIDA, Hiroyuki YAMAGISHI

1995 Volume 44 Issue 504 Pages 1133-1137
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1133

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A new experimental system was developed to record the optical microscopic image of slow crack growth in ceramics together with the applied stress value. The bending stress was applied to pressurelesssintered alumina with Vickers indentation cracks, and the slow crack growth behavior was observed with this new system. The relation between the applied stress intensity factor K_app and P/c^3/2 (P=the indentation load, c=the half crack length) becomes linear with the crack extension. From the linear relation, the fracture toughness K_∞ for long cracks and a χ parameter in equation K_res=χ·P/c^3/2 (K_res=the stress intensity factor due to indentation residual stress) were obtained. The increasing R-curve for small cracks was determined by using the above determined χ parameter. The resistance became constant as the crack extension was longer than 0.15mm, and this constant value was identical to the fracture toughness determined by using a single-edge-precracked beam.

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Single Incidence X-Ray Stress Measurement for All Plane Stress Components Using Imaging Plate of Two-Dimensional X-Ray Detector

Toshihiko SASAKI, Yukio HIROSE

1995 Volume 44 Issue 504 Pages 1138-1143
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1138

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This study was performed to examine the possibility of X-ray measurement by analyzing the whole part of Debye-Scherrer ring. An imaging plate (IP) was used for the detection of X-ray in order to obtain a high degree of accuracy and efficiency. Through the investigation on the Tanaka's method, we proposed new equations for σ_y and τ_xy. We also found that the Tanaka's method involved an assumption that the angle η is constant. So we proposed a new method for the determination of stress from Debye-Scherrer ring without the above approximation on angle η. For the experiment, a new system of processing image data, calculating stresses and a back-reflection Laue camera for IP with a four-point-bending-device was manufactured. The stress applied mechanically with this device was compared to that obtained from the present method. The result showed that it was possible to obtain the stress with the same accuracy as that obtained by the sin²φ method. The advantage of this method is that one can obtain all three components of the stress in a plane stress state from one diffraction ring with single incidence of X-ray beam.

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Microstructural Change of TiAl Intermetallic Compound during Laser Fusion Processing and Mechanical Properties of the Fusion Zone

Akio HIROSE, Yoshihiro ARITA, Kojiro F. KOBAYASHI

1995 Volume 44 Issue 504 Pages 1145-1150
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1145

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Surface melting and fusion welding of a Ti-46 mol%Al-2 mol%Mo intermetallic compound were performed using a 2.5kW CO₂ laser. Microstructures of the laser fusion zones were changed depending upon cooling rate. When the cooling rate at 1390K was above 3000K/s in the laser surface melting, α→γ transformation was suppressed and the fusion zone structure resulted in single phase of α₂. In the cooling rates less than 3000K/s, massive γ phase was seen together with α₂ phase. In the laser welding, whose cooling rates were approximately 80K/s to 1800K/s, the fusion zone microstructure consisted of massive α₂, massive γ and lamellar (α₂+γ) phases. Full lamellar structure was formed in the cooling rates less than 20K/s. The hardness of the fusion zones increased from 315Hv of the base metal hardness to more than 500Hv with increasing cooling rate. While all of the laser surface melted zones included cracking, in the laser welding, crack-free welds could be obtained at traverse speeds below 50.0mm/s and pre-heating temperatures above 673K. In the tensile test, the laser welded specimens without cracking were fractured in the base metal. However, the elongation of the weld metal itself was 1/10 times that of the base metal. The elongation of the weld metal was increased threefold by a heat treatment at 1173K for 0.6ks.

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Deformation in KCl Single Crystal with Spherical Indenter above Room Temperature

Shinzo KOBAYASHI, Isao NAKATA, Sei MIURA

1995 Volume 44 Issue 504 Pages 1151-1156
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1151

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The microscopic deformation mechanism of KCl single crystals under the indentation with a steel ball was studied under the load range of 0.5N-5.0N in the temperature range 20°C-300°C. Indentations were made on the {100} plane, and using the etch pit detecting technique the dislocation structures were investigated on the indented surface and its cross section.
The results obtained are as follows:
(1) The dislocation structure formed on a {100} plane at room temperature consists of a high-dislocation-density range and a wing-shaped area of comparatively low density extending along the ‹110› and ‹100› directions.
(2) Dislocation activities on the {110}₉₀ and {110}₄₅ planes are more active under the testing temperature at 100°C and 200°C than at room temperature. At these testing temperatures, the deformation is mainly caused by the slip on the {110}₉₀ plane under comparatively high loads, while the deformation under the lower loads is caused in the pattern that the slips on the {110}₉₀ and {110}₄₅ planes have almost equal effect on the formation of the dislocation structure.
(3) At 300°C, the slip activities on the slip system besides the {110} ‹110› are observed. Dislocation structures with a pattern of circle in the neighborhood of indent, and with a wing-shaped pattern along the ‹110› direction in the outer range, are observed.
(4) On the cross section, dislocation activities on the {110}₄₅ plane are detected at all testing temperatures. It is confirmed that the secondary slip activities occur on the {100} plane at 300°C.

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Impact Compressive Strength of Continuous Carbon Fiber-Reinforced Silicon Nitride

Kinya OGAWA, Toshihiko NISHIDA, Akira KURAISHI, Fumiko SUGIYAMA

1995 Volume 44 Issue 504 Pages 1157-1163
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1157

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The compressive strength of continuous carbon fiber-reinforced silicon nitride ceramics was investigated experimentally at low and high rates of strain. The orientation dependence of the strength and fracture characteristics was well rationalized in terms of shear deformation pararell and/or perpendicular to the fiber direction. A significant effect of deformation rate on the strength was clarified in the case of shearing delamination, while there was no effect on the strength in the case of splitting fracture. The specimen loaded along the fiber direction was fractured by splitting at the stress well below the tensile fracture stress. Microstructural inhomogenity and microcracks induced during the fabrication process play an important role on the strength and fracture morphology of the material.

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Statistical Fatigue Properties of Ductile Cast Irons

Norihiko HASEGAWA, Kunio FUKUYAMA, Yuuji NISHIKAWA, Kenji INABA

1995 Volume 44 Issue 504 Pages 1164-1170
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1164

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Rotating bending fatigue tests of smooth specimens were carried out at room temperature on a pearlitic ductile cast iron (PDI) and austempered ductile cast iron (ADI). No significant difference due to sampling position from cast blocks in both materials was found in fatigue limit and fatigue life distribution. Then, the statistical fatigue properties of ferritic (FDI), ferritic/pearlitic (FPDI), pearlitic and austemperd ductile cast irons were investigated. The fatigue life distributions of all ductile irons were well represented by the three parameter Weibull distribution modified by the saturated probability of failure. The shape parameters of FDI, FPDI and PDI were in proportion to σ/σ_w independent on microstructure, while the shape parameters of both stress levels in ADI were smaller than unity. The fatigue strength of ADI was highest, but the scatter of fatigue life was largest among the all cast irons.

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Effects of Cooling Condition on Liquid Zinc Embrittlement Cracking and Plating Performance of Hot-Dip Galvanizing Bolts

Susumu KIKUCHI, Gendai ETOH, Kunio FUNAMI, Hideharu SHIMIZU, Heiji SUG ...

1995 Volume 44 Issue 504 Pages 1171-1176
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1171

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Hot-dip galvanized bolts tend to crack during galvanizing at the under-head fillet or thread root on which stress is concentrated. In this study, we investigated the influence of the temperature of cooling water on the occurrence of cracking. We further examined the plating performances under different cooling conditions. The main results obtained are as follows.
(1) Heating of cooling water to a higher temperature is found effective against cracking.
(2) The shower-cooling method is effective against cracking, with almost no difference from the conventional cooling method in plating performance such as plating microstructure or cramping torque coefficient.

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Phase Relation and Electric Properties of Pb(Li_1/4Nb_3/4)O₃-PbTiO₃-PbZrO₃ Ceramics

Yasushi KAWAMURA, Ken TANABE, Ryoutarou MATSUMURA, Hiromu OHUCHI

1995 Volume 44 Issue 504 Pages 1177-1182
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1177

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Solid solution ceramics in the system xPb(Li_1/4Nb_3/4)O₃-yPbTiO₃-zPbZrO₃ were prepared by the solid state reaction of powder materials. The ceramic, dielectric, and piezoelectric properties and crystal structures of the products were studied. The compositions within the ternary system were sintered much more easily than the end compositions, and a well sintered high density ceramics was obtained for the compositions near the morphotropic transformation. Piezoelectric ceramics with high relative dielectric constants, high radial coupling coefficient and low resonant resistance were obtained for the composition near the morphotropic transformation. The composition Pb(Li_1/4Nb_3/4)_0.2Ti_0.4Zr_0.4O₃ showed the highest radial coupling coefficient.

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Back Analysis of Viscoelastic Rock Masses with Circular or Elliptical Tunnel

Yoshihisa SHIBATA, Ken-ichi HIRASHIMA

1995 Volume 44 Issue 504 Pages 1183-1188
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1183

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A back analytical method for the excavation of a circular or elliptical tunnel in viscoelastic medium under in-plane and out-of-plane loadings at infinity is derived by using the theory of linear elasticity and the correspondence principle. The time-dependent behavior of rock masses with initial displacements is assumed to be represented by Standard model of viscoelasticity. The practical usefulness of the consideration of initial displacements and the back analysis is shown by several graphical representations and by the numerical results applied to some virtual measurment data.

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Fundamental Study on Composite Sensitivity Analysis of Electrode Array System for Resistivity Measurements

Tsuyoshi SUGANO

1995 Volume 44 Issue 504 Pages 1189-1195
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1189

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For the geoelectrical measurements and their inversion analysis, a more accurate and reliable resistivity data aquisition system is needed more than ever. As the direct current resistivity method most commonly used for the exploration and evaluation of the target inhomogeneity is a very useful and practical tool for the electrical imaging technique so-called resistivity tomography, it may be exceedingly important to incorporate a new sensitivity method developed by the author for determining more exactly the earth resistivity target inhomogeneity, for examples, faults, fractures, layers, water bearing zones, and geological structures under various conditions and environments. Especially, no technique has been investigated to interprete the local and lateral resistivity changes of the near surface inhomogeneities and detailed deep massive resistivity structures.
In this paper, by composite analysis of sensitivity distributions, the author has clarified the relation among various surface electrode arrays. The two-electrode system, the four-elctrode systems such as the Wenner, the Eltran and the Staggered electrode configuration (so-called the tripotential system) and the six-electrode system have been discussed. Also an example of the sensitivity composite analysis for the solid electrode array system has been investigated as an aid to analyze the response caused by target inhomogeneity more practically.

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Fiber Optic Method for Detection of Impact Induced Damage in Composite Laminates

Shintarou KITADE, Takehito FUKUDA, Katsuhiko OSAKA

1995 Volume 44 Issue 504 Pages 1196-1200
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1196

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In the present paper, the impact induced behaviors of composite laminates were observed by internal monitoring with the embedded fiber optic sensors. The impact induced damage such as delaminations and cracks were detected by sensing the fracture of embedded optical fibers. To establish methods for independently sensing cracks and delaminations, the embedded directions of the optical fibers were changed in various ways. In the delamination detection, optical fibers were curved and embedded along each reinforcing direction in [0°₄/90°₄]_s laminates. To detect cracks, optical fibers were embedded between 90° layers, perpen-dicularly in the reinforcing direction. First, the delamination detection technique was evaluated by the static indentation tests. The tests were conducted with real-time observation of the damage propagation and the fracture of optical fibers using a CCD camera. As these test results, it was proved that optical fiber was broken when the delamination growth was reached within a certain region of the specimen. Second, the falling weight impact tests were conducted with various impact energies. Two optical fibers were embedded in each specimen; one was for crack detection, another was for delamination detection. As the results of the impact tests, it was found that cracks at the middle layer of specimen occurred at the initial stage of impact loading, and then the delaminations at the lower interfaces propagared.

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Computer Simulation on Deformation of Engineering Materials at High Temperature

III: Application to Structural Analysis

Yukio TAKAHASHI

1995 Volume 44 Issue 504 Pages 1201-1206
Published: September 15, 1995
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.44.1201

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