Vol. 6 No. 3 CONTENTS
Special Issue on Microstructure and Mechanical Properties of New Engineering Materials
Regular Articles
Special Issue on Microstructure and Mechanical Properties of New Engineering Materials (Vol.6 No.3)
Preface (Vol.6 No.3)
Preface |
Masataka TOKUDA |
151 |
Review Paper (Vol.6 No.3)
High-Strain-Rate Superplasticity and Its Applications |
 |
Hiroyuki HOSOKAWA and Kenji HIGASHI |
153 |
General Papers (Vol.6 No.3)
The Influence of Tension on the Development of Rolling Textures |
|
Hyung-Joon SHIN, Joong-Kyu AN and Dong Nyung LEE |
161 |
The Evolution of the Goss Texture in Silicon Steel |
|
Dong Nyung LEE |
167 |
Fraction Tensor Measured from Micrographs for Evaluating the Geometrical Orientation of Martensite in TRIP Steel |
|
Takeshi IWAMOTO and Toshio TSUTA |
173 |
Mechanical Properties of TiN Films with the Preferred Orientations by Nano-Indentation Method |
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Akihito MATSUMURO, Tomohiko WATANABE, Toshiyuki HAYASHI, Toshihiko MORI and Yutaka TAKAHASHI |
180 |
Effect of Fiber Surface Treatment on the Interface and Bending Strength of Aramid Short Fiber Composite |
|
A.K.M. MASUD, Kiyoshi ISOGIMI and Jippei SUZUKI |
186 |
Surface Modification by Friction Coating under Water |
|
Jin-Qi LI and Takeshi SHINODA |
193 |
Observation of High Dose H+ Implanted Damaged Layer |
|
Hiroyuki IWATA, Makoto TAKAGI, Yutaka TOKUDA and Toru IMURA |
198 |
Regular Articles (Vol.6 No.3)
General Papers (Vol.6 No.3)
Viscoelastic Behavior of Granite and the Homogenization Analysis |
|
Yong-Seok SEO, Naoki FUJII, Takafumi SEIKI and Yasuaki ICHIKAWA |
203 |
Inverse Analysis Procedure for Identifying Material Parameters of Hypoplastic Constitutive Model for Soils |
|
Piotr DZIADZIUSZKO, Yasuaki ICHIKAWA and Zbigniew SIKORA |
212 |
Effects of Charge/Discharge of Li1-xNi1-yMnyO2 on Their Crystal Structures and Electronic States |
|
Toshihiro MORIGA, Kazuhiro OKAMURA, Kozo WATANABE and Ichiro NAKABAYASHI |
221 |
Short comunication (Vol.6 No.3)
Raman Spectral Changes of Sugi Bark during Thermal Degradation and Carbonization |
Shigeru YAMAUCHI, Yoshinari KIKUCHI and Yasuji KURIMOTO |
227 |
Vol.6 No.3 ABSTRACT
High-Strain-Rate Superplasticity and Its Applications
Hiroyuki HOSOKAWA and Kenji HIGASHI
Abstract:High-strain-rate superplasticity has been observed in many metallic materials such as aluminum alloys and their matrix composites and it is associated with an ultra-fine grained structure of less than about 3 ƒÊm. This high-strain-rate superplasticity is defined in JIS H 7007 by Japanese Standards Association as superplasticity which appears when the rate of strain is 10-2 s-1 or over. These strain rates are considerably higher than the typical forming rate used for the conventional superplastic materials, but rather close to the commercial hot working rates of 10-1 to 10-2 s-1. Its deformation mechanism appears to be different from that of conventional superplastic materials. A new model is considered from the viewpoint of the accommodation mechanism by an accommodation helper such as a liquid or glassy phase. The new mechanism is proposed in which superplasticity is critically controlled by the accommodation helper both to relax the stress concentration resulting from the sliding at grain boundaries and/or interfaces and to limit the build up of internal cavitation and subsequent failure. A few examples of the industrial applications of high-strain-rate superplasticity are demonstrated.
Key Words:Superplasticity, High strain rate, Aluminum materials, Microstructural features, Liquid phase, Cavitation, Near-net-shape
The Influence of Tension on the Development of Rolling Textures
Hyung-Joon SHIN, Joong-Kyu AN and Dong Nyung LEE
Abstract:The texture inhomogeneity during rolling is one of the greatest problems. Especially, shear textures develops more easily during ferritic rolling of steel sheets at high temperatures owing to friction between rolls and the material. In this study, the influence of front and back tension on the texture development during ferritic rolling has been studied. The rolling textures were simulated using the full constraints Taylor-Bishop-Hill model with the strain history obtained from finite element analysis. The calculated textures showed that the back tension rolling could reduce the shear component more effectively than front tension or rolling without tension. However, the experimental results showed that the tension effect was very small compared to the prediction. The results were discussed based on the effects of friction, initial sheet texture, back tension, and flow stress.
Key Words:Ferritic rolling, Inhomogeneous texture, Deformation texture, Tension rolling
The Evolution of the Goss Texture in Silicon Steel
Dong Nyung LEE
Abstract:The Goss orientation, {110}<001>, in about 3% silicon steel has been the subject of speculation from its scientific and technological points of view. The grain oriented silicon steel is made by hot rolling at about 1300Ž, cold rolling, followed by annealing. The Goss texture is formed near the surface layer of a steel sheet when it is rolled in the ƒ¿ phase region at elevated temperatures, because the friction between the sheet and rolls tends to increase with increasing temperature, which in turn increases the shear deformation. The Goss texture remains unchanged even after recrystallization of steel. The Goss texture, which is not stable with respect to plane strain deformation, rotates toward the {111}<112> orientation. The relaxed constraints (RC) model, in which shear strains parallel to the rolling direction may occur, simulates the formation of the {111}<112> orientation. The {111}<112> rolling component is known to lead to the Goss orientation after annealing. The strain energy release maximization model for recrystallization texture advanced by the author predicts the recrystallization texture of {441}<118> from the {111}<112> rolling texture. The {441}<118> orientation yields the Goss orientation when the {441}<118> orientation is expressed by the Gauss type scattering calculated with a half width angle of 12‹. The model also predicts the fact that the Goss texture formed during rolling remains unchanged even after annealing.
Key Words:Si steel, Recrystallization texture, Goss texture, Strain energy release maximization model
Fraction Tensor Measured from Micrographs for Evaluating the Geometrical Orientation of Martensite in TRIP Steel
Takeshi IWAMOTO and Toshio TSUTA
Abstract:There are various kinds of smart materials with a martensitic transformation, such as the shape memory alloy and the tranformation-induced plasticity (TRIP) steel, etc.; their applications to actuators, structural materials, etc., are investigated. The martensitic particles orient against the loading axis in the micro region so that it may be possible to improve their mechanical properties by the control of their orientation like the composite materials. Here, the fraction tensor, which components are the line fractions of the martensite, was defined in order to evaluate the orientation of the martensite. The validity of the the fraction tensor for investigating their orientations is discussed by a comparison of the fabric tensor. Then, the fraction tensors were measured from the micrographs of TRIP steel previously obtained. Furthermore, the orientation of the martensite in the TRIP steel was discussed by a polar diagram of the line fraction and the fraction tensor. Finally, the dependence of the fraction tensor on plastic strain, temperature and stress state was discussed.
Key Words:Strain-induced martensitic transformation, TRIP steel, Line fraction of martensite, Fraction tensor, Geometrical orientation of the martensite
Mechanical Properties of TiN Films with the Preferred Orientations by Nano-Indentation Method
Akihito MATSUMURO, Tomohiko WATANABE, Toshiyuki HAYASHI, Toshihiko MORI and Yutaka TAKAHASHI
Abstract:TiN films with the (111) and (200) preferred orientations were formed on Si(100) and sapphire(0001) substrates by ion-beam-assisted deposition. The difference in the mechanical properties between the (111) and (200) preferred orientation in TiN thin films was clarified by the nano-indentation technique with the trigonal dia- mond tip. The experiments revealed significant differences in hardness H and modulus E* irrespective of the substrate materials. The measured values were H=16 Gpa, E*=316 GPa for the (200) preferred orientation and H=9 GPa, E*=192 GPa for the (111) preferred orientation. The behavior of the plastic deformation in the TiN films was estimated by the cross-sectional SEM observation and the TEM analysis. These microstructural analyses showed significant difference in cross-sectional views of the plastic deformation and the intergranular fracture mechanism.
Key Words:Mechanical properties, TiN film, Preferred orientation, Nano-indentation
Effect of Fiber Surface Treatment on the Interface and Bending Strength of Aramid Short Fiber Composite
A.K.M. MASUD, Kiyoshi ISOGIMI and Jippei SUZUKI
Abstract:Composite materials used in the present study are fabricated by Aramid short fibers and Unsaturated Polyester resin. The bending strength and energy absorption properties of the composite are studied in this paper. From the single-fiber pull-out test it is found that 1 mm fiber is not long enough to reinforce the polyester, thus the strength of the composite made of 1 mm fiber does not increase when compared to that of the resin. But the strength of the composite made of 3 mm fiber starts to increase when compared to that of the resin. The strength and absorbed en-ergy always increases with the length and content of the fiber. Some fiber surface treatments are done in order to in-crease the bonding between the fiber and the matrix.@It is found that these treatments affect the interfacial shear strength and fiber strength simultaneously. As strength is an important property of a new material, the effect of these treatments on the strength is discussed in this paper. The bending strength of the composite is assumed to depend not only on the interfacial shear strength but also on the fiber strength, depending upon the length of the short fibers.
Key Words:Composite material, Bending strength, Pull-out test, Interfacial shear stress, Surface treatment
Surface Modification by Friction Coating under Water
Jin-Qi LI and Takeshi SHINODA
Abstract:The experiments of friction coating under water were carried out in a water bath. A quench hardenable martensitic stainless steel with 1%C-17%Cr was utilized as a coating material and low carbon structural steel as a substrate, using a vertical friction welding machine with a traverse sliding stage. The results showed that the uniform hardness distribution across the transverse section of coatings with refined microstructures had been achieved. The deposition efficiencies of consumable material under water condition were greater than those obtained in air owing to the cooling effect of water. The quenching crack defect had not been observed due to the unique process of friction coating, in which the cooling rate of deposited metals can be adjusted by combination of process parameters. Meanwhile, an attempt had been made to deposit aluminum alloy consumable metals, using the process of underwater friction coating to restrain the formation of upset roll. The sound bounding coatings with substrate had been obtained in a stabilized coating process.
Key Words:Friction coating, Underwater, Hardness, Refined microstructures, Deposition efficiency
Observation of High Dose H+ Implanted Damaged Layer
Hiroyuki IWATA, Makoto TAKAGI, Yutaka TOKUDA and Toru IMURA
Abstract:The fundamental mechanism underlying the hydrogen exfoliation phenomenon at the damaged layer in Si was investigated. We studied the distribution of the defects as a function of implanted hydrogen dose and clarified the key role of defects in the action of exfoliation. A damaged layer formed by high dose hydrogen implantation in a silicon wafer was observed by cross sectional transmission electron microscopy (XTEM). In the damaged layer caused by hydrogen implantation, (100) defects and (111) defects were observed. The density and size of defects were analyzed and compared with the hydrogen profile obtained by second ion mass spectroscopy (SIMS). The defect distribution was in agreement with the hydrogen concentration obtained by SIMS. The density of (111) defects became higher as the area from the surface deepened, and the sizes of (100) defects and (111) defects grew larger. These results indicate that hydrogen in (111) defects moves toward (100) defects at projection range, and the pressure of hydrogen gas caused by annealing leads to the exfoliation.
Key Words:Hydrogen implantation, SOI, Platelet, Silicon, XTEM, Hydrogen exfoliation
Viscoelastic Behavior of Granite and the Homogenization Analysis
Yong-Seok SEO, Naoki FUJII, Takafumi SEIKI and Yasuaki ICHIKAWA
Abstract:Granite is a composite material of rock-forming minerals with discontinuous joints such as grain boundaries and microcracks. Studies of these microstructures are of increasing interest in geophysics and geotechnical engineering relating to underground space development. We first performed uniaxial compressive and relaxation tests for estimating physical properties of discontinuous joints by using three kinds of rocks that consist of quartz, quartz/feldspar and feldspar, respectively. Next a homogenization method is applied to analyze a viscoelastic behavior of granite including these joints.
Key Words:Granite, Relaxation test, Discontinuous joints, Homogenization method, Viscoelastic problem
Inverse Analysis Procedure for Identifying Material Parameters of Hypoplastic Constitutive Model for Soils
Piotr DZIADZIUSZKO, Yasuaki ICHIKAWA and Zbigniew SIKORA
Abstract:In this paper we present an inverse analysis method for material parameter identification applied to the hypoplastic constitutive model for soils. The proposed method is classified as a direct-approach one, since the discrepancy between the material responses, measured and calculated by means of the finite element method is directly minimized. In the presented work this minimization is made up of the modified Levenberg-Marquardt optimization method based on the so-called trust region approach. We provide a numerical example of parameter identification for a triaxial test performed on a sand material, supplemented by the analysis of the influence of the initial guesses of the parameters to be identified, as well as the errors in the measured control data on the identification process.
Key Words:Inverse analysis, Hypoplastic constitutive model, Levenberg-Marquardt optimization algorithm, Finite element method
Effects of Charge/Discharge of Li1-xNi1-yMnyO2 on Their Crystal Structures and Electronic States
Toshihiro MORIGA, Kazuhiro OKAMURA, Kozo WATANABE and Ichiro NAKABAYASHI
Abstract:The variations of structure and electrochemical properties of Li1-xNi1-yMnyO2 (y=0 and 0.2) were studied as lithium was deintercalated from the materials. The LiNi1-yMnyO2 was prepared by easily available LiOH, Ni(OH)2 and ƒÁ-MnOOH under air flow. Exchange of nickel into the lithium site (3(a) site) made it difficult for the lithium ion to move through the lithium layer, and decreased the electrical capacity for cyclic charge/discharge. Partial substitution of manganese for nickel was effective in preventing abrupt changes of the lattice constant c and Ni-O distances as x increases, resulting in suppressing the phase transitions (hexagonal¨monoclinic¨hexagonal). XPS, XANES and ESR analyses suggested that the charge compensation in charge/discharge of Li1-xNi0.8Mn0.2O2 could be attributed to changing valences of nickel.
Key Words:Lithium nickelate, charge/discharge, XRD-Rietveld, XPS, EXAFS, XANES, ESR