bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the Coupling of Recovery and Precipitation on the Recrystallization Behavior of Ti-Stabilized Extra Low Carbon Steels
Authors: Na Eun Hye , Choi Jae Young , Sung Baek-Seok , Lee Hu Chul
Published: March 2009

The effect of carbo-nitride precipitation on the recrystallization behavior of Ti-stabilized extra low carbon steels was investigated. The precipitation behavior of titanium carbo-nitride was analyzed using transmission electron microscopy (TEM), a chemical extraction method, and the small angle neutron scattering (SANS) method. The recrystallization temperature was varied from 590°C to 680°C depending on the alloy chemistry and hot rolling process. The total amount of
precipitates in the hot bands did not significantly affect the recrystallization temperature of the alloys. Isothermal annealing treatment showed a plateau in the stress relaxation curves, i.e. a delay in the recovery, when precipitation occurred during the annealing treatment. A model developed to explain the dynamic interaction of the precipitation with the recovery in the microalloyed austenite was successfully adopted to simulate the delay of the recovery during the recrystallization treatment
of the cold rolled Ti-stabilized extra low carbon steels.
Solute Drag and Entropy Production - Two Approaches to the Same Phenomenon
Authors: Hillert Mats
Published: March 2009

The historical development of the two approaches to the interaction between solute atoms and a migrating interface, based on dissipation of Gibbs energy and on solute drag, are reviewed and compared. In the way the solute drag was formulated long ago for recrystallization and grain growth, it does not apply to phase transformations. With a new solute drag equation, which was recently proposed, it turns out that the two approaches are completely equivalent for phase transformations as well as grain boundary migration.
Impact of Coil Cooling Rate on Texture, Special Boundaries and Properties of Hot Rolled Strip
Authors: Slavov V.I. , Chaschin V.V. , Kostylev S.N. , Naumova O.M. , Khlybov O.S. , Puchkov A.V.
Published: March 2009

This paper overviews the current state of development of the structure and properties formation in hot rolled low alloy strip steel after its coiling. To clarify the effect of coil cooling rate on the mechanical behavior, hydrogen content, corrosion , texture and coincidence site lattice industrial experiments were made at a hot strip mill. It is revealed that the texture and CSL has a notable influence on the complex of properties: strength, ductility, toughness and corrosion resistance.
Potentiality of Mean-Field Approaches for Recrystallisation: Characterization of the Deformed State of Polycrystals
Authors: Brenner Rénald , Castelnau O. , Bacroix Brigitte
Published: March 2009

The description of the mechanical state of a polycrystal is presented in the
framework of the mean-field approaches and attention is paid to the fields heterogeneity. For nonlinear behaviours, the importance of the chosen model is emphasized with respect to relevant microstructural parameters for recrystallisation.
Recrystallization in Deformed and Heat Treated PET Polymer Sheets
Authors: Raabe Dierk , Chen N.
Published: March 2009

This is a study on texture, decrystallization, and recrystallization in rolled and heat treated semi–crystalline polymers. Experiments were conducted using wide angle Debye-Scherrer-type X– ray diffraction. Changes in crystallinity were quantitatively monitored as a function of strain and annealing time. It was observed that crystallinity drastically drops during deformation in PET. We suggest that amorphization (decrystallization) is a deformation mechanism which acts as an
alternative to crystallographic slip depending on the orientation of the nanocrystalline lamellae. Heat treatment leads to the recrystallization of amorphous PET material and to an enhancement of the original texture of the deformed crystals observed before the heat treatment. We explain this phenomenon in terms of oriented nucleation where amorphous material crystallizes alongside existing crystalline lamellae.
The Effect of Humidity on Recrystallization and Aging of Plastically Deformed Alkali Halide Crystals
Authors: Borisenko E.B. , Gnesin B.A.
Published: March 2009

The effect of water and temperature on grain growth of plastically deformed doped potassium chloride has been studied. The results of experiments show that it is crucial to avoid contact with saturated water vapor in order to prevent a deformed crystal from decomposing. New grains oriented as twins with respect to the initial single crystals, as well as to the deformed matrix, grow fast in the presence of water vapor. The reasons why the properties of the deformed crystals in contact with water vapor deteriorate with time can conceivably be as follows: at first, strontium chloride hexahydrate forms on grain boundaries, then its particles are dissolved by the salt water solution, forming a liquid layer which affects grain boundaries, making a crystal fall to pieces in the end. A deformed matrix can be preserved for more than a year, given that the sample is placed in vacuum for about a month immediately after deformation and then stored at room temperature in the open air. Though a temperature of storage is not that essential in the range from minus -13 to +25°, some special heat treatment after deformation may be useful to dry a sample and, as a result, to defer recrystallization and, therefore, keep mechanical strength at a high level.
A Coupled Recovery/Recrystallisation Model for Zirconium Alloys. Influence of Hydrogen
Authors: Dunlop John , Bréchet Yves , Legras Laurent
Published: March 2009

During transport of spent Zircaloy-4 fuel rods, cladding temperatures can be
expected to rise well over 400°C for transportation periods longer than 10 days. The kinetics of creep under these conditions will be controlled by both strain hardening and the softening effect of static annealing of cold work and irradiation defects. This paper will focus on the development of a coupled recovery/recrystallisation model for Zircaloy-4 from 400 – 520°C.
Coupled Computer Simulations of Recrystallization in Deformed Polycrystals
Authors: Holm Elizabeth A. , Healey Kristopher J. , Battaile Corbett C.
Published: March 2009

Because both nucleation and growth are local phenomena, recrystallization depends on the spatial distribution of strains in a plastically deformed polycrystal. Using a polycrystal plasticity finite element model, we calculated these distributions for equiaxed polycrystals of copper with a random texture. We incorporated the results into a mesoscale recrystallization simulation with a nucleation model based on subgrain evolution. The coupled simulation results indicate that differences in local structure cause significant differences in recrystallization kinetics and grain size distribution. Furthermore, recrystallization in non-uniformly deformed polycrystals, even those with a random texture, is quantitatively and qualitatively different than predicted by continuum models that assume a uniform distribution of strains. This work highlights the need to examine all length scales relevant to the recrystallization process.
Position Resolved In-Situ X-Ray Observation of Recrystallization and Its Description by Self-Organized Criticality
Authors: Wroblewski Thomas
Published: March 2009

A novel X-ray diffraction method, allowing the position resolved imaging of a polycrystalline specimen using the diffracted radiation, was applied for in situ investigation of recrystallization of cold-rolled copper. A large area of the specimen could be observed simultaneously, yielding information about nucleation and growth of many individual crystallites. The recrystallization process showed a stochastic behavior which can be described by the model of self-organized criticality.
Modeling the Impact of Grain Boundary Properties on Microstructural Evolution
Authors: Rollett Anthony D.
Published: March 2009

Much new knowledge has been gained on the properties of grain boundaries that are relevant to processes of microstructural evolution such as grain growth and recrystallization. For mobility, a combination of experiments and numerical simulation has reinforced many of the classical concepts of special crystallographic types with either exceptionally high or exceptionally low mobilities. At another level, the anisotropy of energy of (especially) mobility has long been assumed to play an important role in both grain growth and recrystallization. The process of “micro-growth selection” is assumed to favor, in fcc metals, the development of cube-oriented nuclei in the early stages of recrystallization. We describe simulations in which initial microstructures with varying degrees of verisimilitude to as-deformed microstructures are used, as well as various assumptions about the grain boundary energy and mobility. From these one it is apparent that the anisotropy does indeed effectively promote the cube component development.
Magnetically Driven Selective Grain Growth in Locally Deformed Zn Single Crystals
Authors: Konijnenberg P.J. , Molodov Dmitri A. , Gottstein Günter
Published: March 2009

In magnetically anisotropic materials a driving force for grain boundary migration
can be induced by an external magnetic ¯eld. It is experimentally shown that annealing of locally deformed Zn single crystals in a suitably directed high magnetic ¯eld results in a growth of new individual grains. Velocities of some solitary moving grain boundaries were measured and their absolute mobilities were estimated at a single temperature. Results are discussed in terms of preferential grain orientation and boundary character.
High Angle Grain Boundary Mobilities in a High Purity Single-Phase Al-0.1 wt% Mn Alloy
Authors: Lens Arnaud , Maurice Claire , Driver Julian H.
Published: March 2009

The migration rates (V) of “random” high angle grain boundaries (HAGB) during annealing of a cold deformed (e=1.3) high purity Al-0.1wt% Mn alloy were determined using a combination of in-situ annealing and EBSD in the SEM at temperatures between 200 and 330°C. The SEM heating stage used for these experiments is described and results on the local recrystallization kinetics of the Al-Mn alloy are presented. For this, the local stored energies (P) were determined by subgrain size and misorientation analyses to give the boundary mobilities (M)
through the standard V = M.P equation. The solute drag “force” was analysed with the atomistic model of Lücke and Stüwe (1971) for a “loaded” boundary and used to estimate the diffusion rates in the above temperature range. The activation energies for boundary migration were found to be consistent with those of solute atoms moving behind the grain boundary, i.e. intermediate between the values for bulk and boundary diffusion of Mn.
Some Features of the Triple Junction Motion in Aluminium
Authors: Protasova Svetlana , Sursaeva Vera G.
Published: March 2009

The migration of the systems of tilt grain boundaries with a triple junction (<100>,
<110> and <111>) in high-purity aluminium are presented. The experimental results demonstrate that the motion of grain boundary systems with triple junctions in Al at low temperature can be controlled by slowly moving triple junctions. In the high temperature range the triple junctions less affected the motion of the systems and the activation enthalpy was smaller than that at low temperature. The experiments revealed a drastic difference between activation enthalpy of grain boundary and triple junction motion at different temperatures. The compensation effect (linear dependence of migration activation enthalpy on preexponential mobility factor) at the migration of the systems with triple junction was observed. The compensation temperature was revealed to be close to the temperature for the triple junction
mobility.
Secondary Recrystallization in Grain-Oriented Silicon Steel
Authors: Ushigami Yoshiyuki , Kumano Tomoji , Haratani Tsutomu , Nakamura Shuichi , Takebayashi Shigeto , Kubota Takeshi
Published: March 2009

Mechanism of Goss secondary recrystallization in grain-oriented silicon steel has been investigated by temperature gradient annealing and by in situ observation utilizing synchrotron x-ray topography. The results support the selective growth theory. Migration of Goss grains is controlled by second phase particles (inhibitor) and sharper Goss grains, which have higher frequency of CSL boundaries to the matrix, start to grow preferentially while the other matrix grains are stagnated by inhibitor. CSL boundaries are supposed to have lower grain boundary
energy, thus suffer lower pinning force from the inhibitor and start to migrate at higher inhibition level. Based on this model, we have made a computer simulation and have found that this model successfully depicts the important features of secondary recrystallization; grain growth behavior of secondary grains, secondary grain size and sharpness of Goss texture.
Grain Growth in Al: First Results from a Combined Study of Bulk and In-Situ Experiments Using a Columnar Structured Al Foil
Authors: Piazolo Sandra , Sursaeva Vera G. , Prior David J.
Published: March 2009

First results from grain growth experiments in a columnar structured Al foil show several interesting features: (a) the grain size distribution remains heterogeneous even after up to 300 min. annealing and (b) the Von Neumann-Mullins relation is not always satisfied. To clarify the underlying reasons for these features, in-situ heating experiments within a Scanning Electron Microscope (SEM) were combined with detailed Electron Backscatter Diffraction (EBSD) analysis. These show that the movement of boundaries can be strongly heterogeneous. For example, the complete replacement of one grain by a neighbouring grain without significant change of the surrounding grain boundary topology is frequently seen. Experiments show that grain boundary energy and/or mobility are anisotropic both with respect to misorientation and orientation of grain
boundary plane. Low energy and/or mobility boundaries are commonly low angle boundaries, twin boundaries and boundaries that form traces to a low index plane of at least one of the adjacent grains. As a consequence the Von Neumann-Mullins relation is not always satisfied.
Static Recrystallization of FeAl in the Presence of Second Phase Particles: Experimental and Modeling Investigations
Authors: Guessasma Sofiane , Suzon E. , Rouag N. , Grosdidier Thierry
Published: March 2009

This paper presents some preliminarily results on microstructure modifications associated with static recrystallization in an ODS alloy. The morphology of the grains issued from static recrystallization is influenced significantly by the alignment of the oxide particles in the as-extruded starting material. Grain growth modeling confirms the effect of particle alignment on the grain morphology and shows significant control of the particle distribution nature and the initial grain size on the grain anisotropy.
Introduction of Second Phase Particle Shape in Monte Carlo Grain Growth Simulation
Authors: Guessasma Sofiane , Rouag N.
Published: March 2009

This paper deals with the study of particle shape effect in grain growth inhibition. As it is difficult to quantify analytically such effect during growth kinetic because of particle distribution variation, computer simulation was implemented. Monte Carlo simulation was chosen to follow grain growth in presence of incoherent particles varying their size, fraction and morphology. Results suggested a correlated effect between particle eccentricity and fraction to control growth inhibition. Moreover, particle size controlled better growth kinetic, as it was possible to inhibit particle shape effect by giving a size advantage to particles having a high symmetry.
Correlating Surface Functionality with Machining Conditions in Precision Machining Processes
Authors: Luo X.C. , Cheng K. , Ward R.
Published: March 2009

This paper attempts to correlate surface functionality generation with machining
conditions by computer simulation and machining trials. The linear and nonlinear machining conditions, such as feed rate, built-up-edge, shear- localized chip formation, regenerative chatter are modelled in the light of their physical features. They are the inputs to the integrated surface topography generation model. The dynamic tool path is calculated through the dynamic cutting force model and surface response model. The surface is generated by transforming the tool profile onto the workpiece surface along the dynamic tool path. All of these models are integrated in a user-friendly Matlab Simulink environment. On the basis of the Simulink model, the dynamic simulation is performed to predict the 3D machined surface topography and its functionality. The simulation results have been validated by precision turning trials. The spectrum analysis of the machining dynamics and surface topography shows that surface generation is highly affected by the nonlinear factors in precision turning process. A case study shows the feasibility of generating some
functional surface for some product/component through controlling machining variables.
Abnormality Detection by Analysis of Cutting Sound
Authors: Chen Lian Yi , Osawa T. , Narita H. , Nakamura Takashi , Fujimoto H.
Published: March 2009

This study deals with the construction of network system for the production site, for the purpose of networking the machine tools as a part of the whole system. The Tele-monitoring for transformation of monitored information was studied. From the point of view of monitoring, the recognition of abnormal is very important in reducing the burden of an operator or for long-time unmanned operations. We then propose a method for the detection of abnormal in cutting process by analyzing the cutting sounds using Fourier transform, filtering, correlation analysis and statistic treatment. For the checking of tool wearing progressing, an experiment was arranged for the
recognition of the sounds from a worn tip in comparison with a new one. On the detection of tipping of the cutter, a new tip is used for a long-time cutting without tool exchanging. The change of worn width and related values were compared with the original standard. It was found that the detection of tipping is possible by continuously sampling the cutting sounds and monitoring their correlation.
Modern Analysis and Design for the Generalized Lubrication System of Internal Combustion Engine
Authors: Liu Ming , Cheng Fang Qi , Fan Xianfeng , Ge Pei Qi
Published: March 2009

More precise analysis and design of generalized lubrication system with the research results of modern lubrication theories are the effective measures to improve the efficiency and reliability of internal combustion engine. Through discussing and summarizing the development status in this field, a set of systematic methods of integrated analysis and design, and general rules are proposed in this paper. Technical measures for lubrication design of internal combustion engine are given. The database of lubrication design and condition monitoring is suggested to found. The best dispose of lubrication system design will be obtained through modeling, deducing control equation, and numerical simulation, improving and optimizing the coupling relationship among the capacity design, structure design, and lubrication design. Such, the modern lubrication design can be combined with strength design at the period of concert design and scheme design period really.
Effect of Whisker Content on Mechanical Properties and Microstructure of Hydroxyapatite-SiCw Composite Bioceramics
Authors: Niu Zong Wei , Zhang Jian Hua , Ren Sheng Feng , Li Li , Xu Min Gang
Published: March 2009

Theory calculation result indicates that the maximal critical content of SiCw in hydroxyapatite-SiCw composite bioceramics is 23.7%. Hydroxyapatite-SiCw composite micropowder was synthesized using in-situ composite method, and hydroxyapatite-SiCw composite bioceramics with different content of SiCw were produced by hot pressing sintering method. The microstructures of the materials were analyzed by SEM, and the mechanical properties were tested. The results show that the mechanical properties of composite material are the best when the whisker content is 20~23.7%.
Development of a Cutting Database System with Prediction and Analysis Functions
Authors: Wan Yi , Liu Zhan Qiang , Ai Xing , Liu J.G.
Published: March 2009

Cutting tool and machining parameters selection are central activity in process planning, which was traditionally performed by numerical control programmers or machine tool operators. The surface integrity has great effect on part quality and the sudden tool failure increases the machining costs greatly. The present paper details the development of a cutting database system with surface integrity prediction and tool failure analysis functions (CUT-P&A). The design and implement of this
system has been presented. The system includes three main modules: cutting database, premature tool failure analysis and surface integrity prediction. The functions of this system include cutting tool selection and machining parameters recommendation, prediction of surface integrity and premature tool wear analysis. A case has been studied to explain the application of the system. The wide application of this system will be helpful for machining tool programmers, the improvement of
machined part quality and the reduction of machine cost.
Tool Geometry Effect on Machined Surface Integrity in Precision Turning High-Strength Spring Steel
Authors: Wang H.X. , Zong Wen Jun , Liang Ying Chun , Dong Shen
Published: March 2009

In this paper, Based on regression analysis of tests, three comprehensive experimental models were presented in precision turning high-strength spring steel, Vicker’s hardness, residual stresses and surface roughness can be predicted utilizing these models. And the influence of tool geometry on machined surface integrity was analyzed systematically. The analytical results show that Vicker’s hardness and compressive residual stress will increase with the decrease of rake angle, clearance angle, cutting edge angle or minor cutting edge angle, surface roughness increases with an increase of rake angle or clearance angle and decreases with an increase of cutting edge angle or minor cutting edge angle.
Pneumatic Proportional Position Control System Based on BP Neural Networks
Authors: Liu Y.J. , Kong X.Z. , Li Z.W.
Published: March 2009

A PID controller based on Back-propagation neural networks is presented and used to the pneumatic proportional positioning system in this paper. A proportional valve-cylinder without rod system for buffering and positioning, which is controlled by microcomputer, is designed and completed in this paper. The experimental results show that the system gains self-adaptability because of the application of this control method. And the buffering and positioning of the cylinder can be implemented under different working conditions.
The Inverse Kinematics Algorithm of Redundant DOF Robot
Authors: Wang Yong , Wang L.
Published: March 2009

A new analytic model for the inverse kinematics of redundant robot is developed based on optimization measure that is defined as a criterion to determine the optimization adaptability. A smoothly continuous function of optimization measure is derived. The redundant seven-DOF robot is kinematically simulated using MATLAB software. Results show that self-motion of joints can vary continuously and the joint angular velocity can be controlled within the smaller range by using the new model for the inverse kinematics of redundant robot.
Balanced Octree for Tetrahedral Mesh Generation
Authors: Au Kin Man , Yu Kai Ming
Published: March 2009

Nowadays, with the advances of Finite Element Analysis (FEA) packages, some of the engineering and design problems such as stress or thermal deformation can be successfully solved. These are convenient for better incorporating the design constraints of various tasks such as injection molded parts, or rapid prototyping and tooling. Mesh generation is the major step of finite element method for numerical computation. Common types of mesh include triangulation or tetrahedralization. During the mesh generation process, we always find difficulty in the formation of a uniform, non-conformal mesh. The undesirable mesh will adversely influence the accuracy and meshing time of the model. This paper will, thus, propose an effective approach to extend to threedimensional (3D) mesh generation by octree balancing method so as to adjust the mesh pattern. In this paper, the implementation of octree balancing will be explained and illustrated with real life example. The proposed method includes three main steps. Problematic unbalanced octants will be
detected and Steiner points will be added as appropriate before the tetrahedral mesh generation. The balanced octree will form good tetrahedral meshes for further analysis. Then the balanced and unbalanced meshes will be compared for efficiency and accuracy for mesh generation.
Research on Surface Quality Control of Moulds Formed by Plasma Arc Spraying
Authors: Deng Qi Lin , Sun K.K. , Zhou G.C. , Song Jian Li , Wang Y. , Hu De Jin
Published: March 2009

Rapid manufacturing moulds by plasma arc spraying is a new kind of plasma arc
machining technology. This technology has many advantages. An experimental apparatus has been set up. The influence of some special factors on the surface quality of work moulds formed by plasma arc spraying have been analyzed and experimentally researched. The micro structure of the interface between master moulds and work moulds shows that work moulds copy geometrically master moulds very well after optimizing processing parameters. Some experimental samples by
plasma arc spraying have been obtained. They show that the surface patterns of work moulds match with the ones of master molds very well.
A Study on Vacuum Brazing Procedure of Plate Heat Exchanger
Authors: Zhang Sheng Sheng , Cheng Y.H. , Cheng L.
Published: March 2009

The effects of work-piece heating temperature, holding time, and vacuity upon the
quality of soldered fittings, when welding stainless heat exchanger (0cr17Ni12Mo2 plate) by vacuum brazing, are discussed in this paper. It also presents an optimized brazing procedure of welding heat exchanger. The processing property of soldered corrosion-resistant plate handled by the brazing procedure are discussed and optimized. Based on the analysis of samples taken from different sections of the welding seams, the paper studies the joint structure of brazing stainless steel.
Finite Element Analysis for Deformation of Toolholder/Spindle Interface System at High Rotation Speed
Authors: Wang D.L. , Li T.H. , Kang D.C.
Published: March 2009

With a significant progress achieved both in new kind of cutting tools and in machine tool design at high cutting speed, one of the weakest parts in the machining system is the toolholder/spindle interface system. In this paper the displacement of the 7/24 tapered tool interface and the HSK tool interface at high rotation speed is analyzed by means of the finite element method. The effects of the centrifugal force on the characteristics of the joints are investigated.
Manufacturability of Fractal Geometry
Authors: Yeung Y.C. , Yu Kai Ming
Published: March 2009

Nowadays more and more aesthetic product developments, assemblage and decoration designs are taking aesthetically appealing forms of natural objects such as rough terrain, ripples on lakes, coastline and seafloor topography. They are mathematical definable via fractal geometry theory and emerge to attract a lot of attention. However, not many methods for manufacturing of fractal objects have been reported in the literature and no previous research papers concern the manufacturability of fractal geometry. The paper will, thus, give a tentative classification and nomenclature of fractal geometry. Then, a state-of-the-art overview of manufacturing techniques is presented. By bridging the gap between fractal geometry and manufacturing, those processes that are promising to manufacture the three dimensional (3D) fractal objects will be highlighted. Afterward, a brief overview of limitation of those processes will be discussed.
Approach to the Improvement of Laser Cutting Accuracy for Laminated Solid Manufacture by Dynamic Compensation
Authors: Wang G. , Liu K.
Published: March 2009

Laser cutting process plays a key role in obtaining accurate parts in Laminated Solid
Manufacture. Conventional laser cutting machine adopts motion control scheme. For further improving the cutting accuracy, dynamic factors are to be taken into account. The dynamic compensation scheme is proposed. The method combines the advantages of close-loop position control and computed torque control. Different from other presented schemes, the method is not model-based. A multilayer neural network is employed to realize the inverse mechanic dynamics. The complicated dynamic parameter identification problem becomes the learning process under
supervision. Experiments have been conducted to verify the proposed method for improving the laser cutting accuracy.
A Surface Modification Method by EDM and Its Application to Cutting Tools
Authors: Zhao Wan Sheng , Fang Yu , Wang Zhen Long , Li L.H.
Published: March 2009

This paper describes a new surface modification method by Electrical Discharge
Machining (EDM) to create a hard ceramic layer on the workpiece. When a kind of metallic material that makes hard carbide is used as an electrode of EDM, hard ceramic layer can be deposited in a certain condition in the process of EDM. In this paper, characteristics of the layer and the application of this method to cutting tools are discussed. First, the principle of this surface modification method is shown. Secondly, the characteristics of the layer are studied in detail. Through the discuss of wear characteristics of the electrode and formation characteristics of the
layer, it can be found that there are some distinct differences between the traditional EDM technology and this new EDM surface modification method. Thirdly, the micro-hardness test of the layer at the different distance from the base metal is carried out. It shows that there is a hard area also under the surface of base metal. At last, as an application of EDM surface modification method, cutting test of cutting tools is done, and it confirms that the life of the cutting tool by EDM surface modification is much longer than that of without layer.
Investigation on Influencing Factors of AFM Micro Probe Nanomachining
Authors: Yan Yong Da , Dong Shen , Sun T.
Published: March 2009

This study aimed to gain an in-depth understanding of the features of AFM micro probe nanomachining. With the aid of the orthogonal test analysis and synthesis method of point rating, factors of influencing the cutting process: the perpendicular load, the feed amount and the cutting speed, were analyzed. The study revealed that the feed amount and the perpendicular load had greater effect on the surface quality and machining efficiency than the cutting speed. The results were also compared with the conventional ultra-precision machining. The optimal machining parameters suitable for two application fields were achieved. This method is a novel and feasible method to perform the nanomachining.
Collision and Determination of Workpiece Location in Parallel Mechanism Type Machine Tools
Authors: Zhao X.M. , Bi Y.Z. , Wang Hai Long
Published: March 2009

This paper uses HexaM made by Toyoda Machine Works Co. as an analytical model of parallel mechanism type machine tools. Much collision may be generated for its complicated structure and working space, using this machine. For example, those collisions are generated between the moving components of the parallel mechanism, between the moving components and a workpiece and between the moving components and the tool storage for automatic changing. In this paper, an
algorithm for detecting and avoiding those collisions is proposed. The method for avoiding the collisions is conducted by readjusting the location of the workpiece without amending the tool path. It is confirmed through experimental works that the proposed algorithm is useful for detecting the collisions and determining the location of the workpiece prior to the actual machining.
Taguchi Methods to Optimize TiN Coating Surface Roughness
Authors: Yim S.L. , Yu Kai Ming , Kwok D. , Lee Tai Chiu
Published: March 2009

Cathodic Arc Physical Vapor deposition (CAPVD) uses a high current, low and negative voltage arc to vaporize a cathodic electrode (cathodic arc) and deposit the vaporized material on a substrate. The vaporized material is ionized in a vacuum chamber and the substrates are usually biased so as to accelerate the ions to the substrate surface. CAPVD provides a very dense film with excellent adhesion to the substrates. Therefore, this technique is mainly used to deposit on cutting tools such as end mills, drills, inserts, plastics and metal molds and high wear resistance tribology components. However, this coating technique will produce unwanted micro particles (droplets) [1] which usually are the target materials that cannot be reacted in coating process. These particles will affect the coating roughness and the surface morphology. To optimize this condition, Taguchi method is introduced to obtain the best experimental parameter settings. In this study, Atomic Force Microscope (AFM) is used to analyze the roughness of the coating for the following factors: bias voltage, arc current, nitrogen pressure and coating thickness.
Study on Process Decision Methodology for Sheet Metal Stamping by Case Based Technology
Authors: Liu W. , Yang Yu Ying , Xing Z.W.
Published: March 2009

More powerful process design methods and tools of sheet metal stamping are needed to help engineers design better products, to reduce lead times and costs, and to increase product performance and accuracy. A novel model for representation of object-oriented case information constitution relationship is
presented, ‘Class-Property’ structure is proposed in order to refine the case representation, multi-types, properties are adopt to describe more detailed information, three hierarchies of index strategy are used to realize case extraction. Furthermore, experts’ knowledge and experience on previous design cases and
forming problems are collected, which can provide designers useful practical experience and data to aid design procedure and to solve the potential problems of sheet metal stamping. In order to illustrate these applications, database technology is used to realize a prototype system of auto body panels, which can be used to integrate process design information and manufacture resources.
Fatigue Crack Growth Tests on Glass Fibre Reinforced Polymer Matrix Composite
Authors: Csomós Zilia , Lukács János
Published: March 2009

E-glass fibre reinforced polyester matrix composite was investigated, which was made by pullwinding process. Round three point bending (RTPB) specimens were tested under quasi-static and mode I cyclic loading conditions. Load vs. displacement (F-f), load vs. crack opening displacement (F-v) and crack opening displacement range vs. number of cycles (ΔCOD-N) curves were registered and analysed. Interfacial cracks were caused the final longitudinal fracture of the specimens under quasi-static and cyclic loading conditions.
Determination of Residual Stresses in Hot Extruded Rod
Authors: Törköly Tamás , Ziaja György , Viczián György
Published: March 2009

The relative low density of aluminum is well known for a long time, but its adaptability is limited by mechanical and thermal expansion properties. These unfavorable properties can be significantly improved by powder metallurgy. The produced material has a non-equilibrium state; it follows from the power metallurgy, so arises the question of the measurement of residual stress. We produced some square rod for our experiment with different tool geometry, thus the deformation histories of this specimens were different too. We measured the residual stress of this specimens by means of strain-gauges.
A Search for New Red and Green Phosphors Using a Computational Evolutionary Optimization Process
Authors: Lee Jae Moon , Yoo Jeong Gon , Kim Ji Sik , Sohn Kee Sun
Published: March 2009

An evolutionary optimization process involving a genetic algorithm and combinatorial
chemistry (combi-chem) was tailored exclusively for the development of LED phosphors. The genetic algorithm assisted combi-chem (GACC) is a well-known, very efficient heuristic optimization method. Therefore the combination of a genetic algorithm and combi-chem would enhance the searching efficiency when applied to phosphor screening. The ultimate goal of our study was to develop oxide red and green phosphors, which are suitable for three-band white light emitting diodes (LED). In this regard, promising red and green phosphors for three-band white LED applications, such as Eu0.14Mg0.18Ca0.07Ba0.12B0.17Si0.32Od and Tb0.01Gd0.02Ce0.04B0.1Si0.83Od, were obtained.
Effect of Nb-Content on Mechanical Properties of (Ni47Ti44)100-xNbx Shape Memory Alloys
Authors: He Xiang Ming , Yan De Sheng , Jiang Zhi Min , Rong Li Jian
Published: March 2009

A ternary alloying element Niobium addition to the Ni-Ti shape memory alloy could
optimize transformation temperatures, mechanical properties. In this paper, with the help of ambient tensile test and scan electron microscope observation, the influences of Nb-content on the mechanical properties of (Ni47Ti44)100-xNbx alloys were investigated in detail. The results indicated that both the fracture strength (sb) and the elongation (d) decreased gradually with the increasing of the Nb content. The fracture surfaces showed the fracture character of the alloys was clearly gliding fracture, which is typically transgranular fracture mode.
A New Method to Determine the Activation Energy for Hydrogen Desorption from Steels
Authors: Wei Fu Gao , Tsuzaki Kaneaki , Hara Toru
Published: March 2009

A new method has been developed to determine the activation energy for hydrogen
desorption from steels by means of thermal desorption spectrometry (TDS). This method directly fits the Kissinger’s reaction kinetic formula dX/dt=A(1-X)exp(-Ed/RT) to experimentally measured thermal desorption spectrum and best fit yields the activation energy (Ed) and the value of constant A. It has been proven that this new method is applicable to precise measurement of the activation energy for hydrogen desorption from incoherent TiC particle, coherent TiC precipitate, grain boundary and dislocation in 0.05C-0.20Ti-2.0Ni and 0.42C-0.30Ti steels.
Influence of In-Flight Particle Characteristics on the Forming Quality
Authors: Fang Jian Cheng , Xu Wen Ji , Zhao Zhi Yu , Wang L.
Published: March 2009

There are many technical parameters influencing on the coating quality in plasma spray forming which has become an important technology in materials processing. In this study, the relationships between the melting state, in-flight property of particles injected into plasma jet and the forming quality have been investigated. The experimental results show that the temperature field distributions of plasma jet are mainly affected by plasma generator power though CCD imaging and gray-scale processing. The velocity of in-flight particle is directly determined by the flow rate of
work gas, and the surface temperature of in-flight particle is obviously affected by assisted gas rate. It is clear that the energy coupling and momentum transferring between plasma and particle have a significant influence on deposition efficiency, porosity, microhardness and microstructure of spray-formed parts, and it also provides a good idea to control the forming quality on-line.
Effect of Austenite Grain Size on Martensitic Transformation of a Low Alloy Steel
Authors: Lee Seok Jae , Lee Young-Kook
Published: March 2009

There are many empirical equations for predicting martensite start temperature (Ms) and the kinetics models of martensitic transformation of plain carbon and low alloy steels. The Ms temperature equations are only dependent upon the chemistry, while the martensite transformation kinetics models are based on the degree of undercooling below Ms temperature. However, the prior austenite grain size (AGS) is also expected to influence both Ms temperature and martensite
transformation kinetics as it does in diffusive transformations. In this study, herefore, both Ms temperature and martensite transformation kinetics of a low alloy steel with different austenite grain sizes were investigated using a dilatometer. The new Ms equation and martensite transformation kinetics model including the AGS effect are proposed.
Spatially Resolved Core Level Spectroscopy of Nanotubes
Authors: Sun Yue Kui , Yuan Jun
Published: March 2009

In core-level electron energy loss spectroscopy (EELS) for anisotropic systems, the applied electric field is determined by the momentum transfer vector q, therefore the collection solid angle range for the scattering electrons and sample orientation will affect the measured EELS spectra.. Using the spatially resolved C 1s core excitation in carbon nanotube as an example, we show that the EELS measurement can be understood by a simple dipole theory of anisotropic core loss spectroscopy which decomposes the spectral contribution in terms of orientationelly averaged
isotropic spectrum and linear dichrotic spectrum. In addition, we point out the Magic Angle (MA) conditions that allow the direct determination of the averaged spectra acquired independent of the exact sample orientation.
The Joint Characteristics of Friction Stir Welded Mg-Zn-Y Alloy
Authors: Lee Chang Yong , Lee Won Bae , Yeon Yun Mo , Jung Seung Boo
Published: March 2009

Friction stir welding of similar Mg-Zn-Y alloy was successfully carried out under various welding conditions. The external shape of the joints showed good quality and the weld zone perpendicular to the welding direction didn’t also include any defects. In the weld zone, the strengthening particles were homogeneously dispersed in the Mg matrix. The morphology of these particles was slightly varied with the welding speed and with the location such as SZ, TMAZ, HAZ and BM. The shear band caused by the severe deformation was observed in the TMAZ. SZ had a
higher hardness than that of the base metal. Though UTS of the joints slightly varied with welding speed, it reached the equal value with that of BM.
Electron Beam-Induced Nano-Deposition Using a Transmission Electron Microscope
Authors: Shimojo Masayuki , Mitsuishi Kazutaka , Tanaka M. , Song M. , Furuya Kazuo
Published: March 2009

Nanometre-sized structures were fabricated by electron beam-induced deposition in a scanning transmission electron microscope. A small amount of metal-organic gases, W(CO)6 and dimethyl acetylacetonato gold, were introduced near a substrate in the chamber of the microscope. The gas was decomposed by the irradiation of focused electron beams and nanometre-sized deposits containing W or Au were produced. Moving the beam position enables us to produce structures with a variety of shapes. High-resolution electron microscopy observation revealed that the structures consisted of nano-crystalline and amorphous parts.
Microstructural Differences of Adhered Material in the Tool Edge and Tool Rake Face. Application to the Machining of Al Alloys
Authors: Sánchez J.M. , Sebastián M.A. , González J.M. , Carrilero M.S. , Marcos Bárcena Mariano
Published: March 2009

Tool adhesion wear can be produced by two different ways. On the one hand, direct
adhesion wear is caused by the incorporation of tool particles to the chips. On the other hand, indirect adhesion wear is caused by the incorporation of fragment of the workpiece material to the tool. When these fragments are removed, they can drag out tool particles causing tool wear. Indirect adhesion can be localised in the tool edge, giving rise to Built-Up Edge (BUE), or in the tool rake face, giving rise to Built-Up Layer (BUL). In this work microstructural differences between both
effects in different machining processes of Al-Cu alloys have been analysed. From these microstructural differences, a model has been proposed for the mechanism of formation of both effects.
Cd1-xMnxS Nanoparticles: Far-Infrared Phonon Spectroscopy
Authors: Romčević N.Ž , Kostić R. , Romčević M.J. , Grujić-Brojčin M. , Čomor M.I. , Vodnik V.V. , Nedeljković J.M.
Published: March 2009

Phonon spectra of Cd1-xMnxS (x = 0; 0.01; 0.05; 0.1; 0.15; 0.3) nanoparticles (d ~ 4.5 nm) have been investigated by far-infrared reflection (FIR) (spectral range 40 - 600 cm-1, temperature range 80 – 300 K) and Raman spectroscopy (100 – 700 cm-1, 300 K). Cd1-xMnxS nanoparticles have been synthesized by using aqueous solution precipitation. We obtained interesting features in FIR spectra: there are expected modes of bulk CdS (240 cm-1, 300 cm-1), new modes connected with nano-size of CdS (130 cm-1, 170 cm-1) and additional mode at 120 cm-1 in Cd1-xMnxS nanoparticles which can be assigned to the presence of Mn. The position of obtained modes is discussed in the frame of the linear chain model with both mass and force constant defects. Raman spectroscopy gives us only the mode at 300 cm-1 and its second harmonic.
Physical Properties of Fluoride Glasses for Ionics
Authors: Trnovcová Viera , Zakalyukin R.M. , Sorokin N.I. , Ležal D. , Fedorov P.P. , Illeková Emília , Škubla Andrej , Kadlečíková M.
Published: March 2009

The ionic conductivity and permittivity of glasses based on ZrF4, BaF2, LaF3, AlF3 and NaF (ZBLAN) or PbF2, InF3, BaF2, AlF3 and LaF3 (PIBAL) are studied. The influence of the glass composition on the glass transition temperature (Tg) and on the crystallization temperature (Tx) is reported. For all ZBLAN glasses the temperature dependencies of the ionic conductivity are close one to another (s500 = 8(2)·10-6 S/cm) and their conduction activation enthalpies are equal to 0.82(1)eV. From the point of view of the ionic conductivity, the best glass compositions are the PIBAL50 (50 m/o PbF2) and PIB45 ( 45 m/o PbF2).
Corrosion Study of Concrete Using PGNAA Technique
Authors: Naqvi A.A. , Nagadi M.M. , Al-Amoudi O.S.B.
Published: March 2009

Monitoring of elemental composition of structural concrete is required to protect
reinforcing steel in concrete against corrosion. Prompt Gamma Neutron Activation Analysis (PGNAA) technique has been used to measure the elemental composition of concrete samples. In this study 2.8 MeV neutron-based PGNAA setup at King Fahd University of Petroleum and Minerals (KFUPM) has been tested for elemental analysis of concrete sample. Later the setup will be used to
measure chloride and sulfate ion concentration in concrete samples. Corrosion of reinforcing steel in concrete is believed to be caused by chloride and sulfate ions.
In the KFUPM PGNAA facility the prompt gamma rays are produced through capture of thermal neutrons in bulk sample. The sample size, to be used with PGNAA setup, is determined through Monte Carlo simulations. In this study, prompt gamma ray yield from calcium and silicon present in the concrete sample was measured for various thickness of the front moderator of the PGNAA setup.
The experimental yield of prompt gamma ray was compared with the results of the Monte Carlo simulations and an excellent agreement has been achieved between the two. The study has shown that the PGNAA technique can be successfully applied for elemental analysis of the concrete samples
Simulation of Thixocasting Processes in Automotive Component
Authors: Forn Antonio , Menargues Sergi , Martín Enric , Chiarmetta G.L.
Published: March 2009

Thixocasting or semi-solid casting is an alternative to the traditional casting processes. A numerical simulation of these methods is useful to define the real process. A new test concept will be presented to determine parameters, such as temperature and rates, as well as the die filling and solidification processes. The simulation tools permit us to understand better the processes, to predict and to eliminate potential defects before they take place. The studied component is a steering knuckle made of an A357 aluminium alloy. The microstructure is characterized by optical microscopy. It has been preceded to the development of a model based on the experimental data, it has been defined to the semi-solid as an homogeneous material with thixotropic properties, and the microstructure is a structural parameter. The results are compared with real tests.