bluuebunny/crossref_metadata_2025 huggingface dataset:
Process Performances Evaluation Using a Specific Shape Factor in the Case of Sheet Hydroforming
Authors: Del Prete Antonio , Papadia Gabriele , Anglani Alfredo
Published: March 2009

The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the time required. Accurate simulation results are fundamental for the tooling and the product designs. Many factors can influence the final simulation result like for example a suitable yield criterion [1]. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Currently, industrial goals of the forming simulation can be summarized in three main groups [2]: time reduction, costs reduction, increase of product quality. Many studies have been carried out about: materials, yield criteria [3, 4, 5] and plastic deformation [6, 7, 8], process parameters [9, 10, 11] and their optimization, geometry modification of the stamped part to evaluate if process responses modifications are required, reaching the goal to perform a virtual tryout of the whole deformation process [12]. In this paper proper metal forming numerical model and experimental analysis have been developed in order to foresee process responses in the case of sheet hydroforming technology. The interactions among the process performances and its variables are the most interesting aspects of the research because their knowledge means the possibility to drive the process feasibility which can be represented by the absence of ruptures and/or wrinkles in the stamped component. This paper analyzes the sheet thickness variation during the hydroforming process, according to a specifically defined “shape ratio”, useful to characterize product’s geometry. The latter is an hydroformed product characterized by a rectangular characteristic section with a drawing depth of 150mm, obtained by a hydroforming operation on a blank having a hexagonal shape. The physical and numerical experimentations were carried out on multiple geometries, different each others in punch radius and die radius, and on multiple materials, steel FeP04 (with a thickness of 1mm and 0,7mm) and Aluminum Al6061 (with a thickness of 0,7mm). The numerical simulation, validated by the experimental investigations [13,14], allowed to define a relationship, specific for sheet metal hydroforming, between the defined shape ratio and the key performance indicator, that is the percentage reduction thickness measured on specific areas of the formed part. The development of numerical models with an high level accuracy could give the real possibility to evaluate process feasibility with different combinations of geometrical and materials parameters without, at the first glance, simulation but only analyzing the specific curves (y = percentage reduction thickness, x = shape ratio).
Simulating the UltraSTEELTM Surface Dimpling Process
Authors: Wang Chang J. , Mynors Diane J. , English Martin
Published: March 2009

The UltraSTEELTM process, developed by Hadley Industries Plc (Hadleys), is a novel surface dimpling process used on steel strip prior to cold roll forming. This dimpling process increases the strength of the final rolled products and enhances other product properties such as fire test performance and screw retention.
Reported in this paper are the results of finite element analysis conducted to simulate the application of the spatially distributed dimple pattern to the metal sheet prior to the cold roll forming process.
The model contains a representation of the two rotating rolls that plastically deform, imparting the spatially distributed dimple pattern on the sheet as it moves between them.
The simulation results are compared with industrially processed UltraSTEELTM steel sheet. Consideration is given to the plastic region developed in the dimples and the effect of rolling action on the regions. The dimensional change of the metal sheet is also discussed.
Deep Drawing Process Design: A Multi Objective Optimization Approach
Authors: Di Lorenzo Rosanna , Ingarao Giuseppe , Marretta Laura , Micari Fabrizio
Published: March 2009

In sheet metal forming most of the problems are multi objective problems, generally characterized by conflicting objectives. The definition of proper parameters aimed to prevent both wrinkles and fracture is a typical example of an optimization problem in sheet metal forming characterized by conflicting goals. What is more, nowadays, a great interest would be focused on the availability of a cluster of possible optimal solutions instead of a single one, particularly in an industrial environment. Thus, the design parameters calibration, accomplishing all the objectives, is difficult and sometimes unsuccessful. In order to overcome this drawback a multi-objectives optimization procedure based on Pareto optimal solution search techniques seems a very attractive approach to deal with sheet metal forming processes design. In this paper, an integration between numerical simulations, response surface methodology and Pareto optimal solution search techniques was applied in order to design a rectangular deep drawing process. In particular, the initial blank shape and the blank holder force history were optimized as design variables in order to accomplish two different objectives: reduce excessive thinning and avoid wrinkling occurrence. The steps of the optimization procedure include: 1) application of Central Composite Design (CCD) for the identification of the necessary data over the domain of variation of the design variables; 2) numerical simulations of the samples identified by CCD; 3) development of a response surface model to interpret the final objectives as functions of the design variables; 4) Pareto optimal solution analysis to reach the most performing design variables. The final aim is to develop a predictive tool able to identify a sort of process window for the analyzed process also minimizing the computational effort in particular with respect to mono-objective optimization techniques or traditional trial and error methods. Many possible technological scenarios were investigated by the implemented procedure and a set of reliable solutions, i.e. able to satisfy different design requirements, were obtained.
Ohmic Contact Formation on Silicon-doped Gallium Nitride Epilayers by Low Temperature Annealing
Authors: Tan L.S. , Raman A. , Ng K.M. , Chua S.J. , Wee A.T.S. , Lim S.L.
Published: March 2009

“removed due to double publication”. The original paper: Journal: Semiconductor Science and Technology Create an alertIssue Volume 15, Number 6 Citation: L S Tan et al 2000 Semicond. Sci. Technol. 15 585 doi: 10.1088/0268-1242/15/6/317 can be accesses at IOP: http://iopscience.iop.org/0268-1242/15/6/317
Line Broadening Analysis Using FullProf*: Determination of Microstructural Properties
Authors: Rodríquez-Carvajal Juan , Roisnel Thierry
Published: March 2009

A short account of the methodology used within FullProf to extract average micro-structural properties from the analysis of broadened lines of constant wavelength diffraction patterns is presented. The approach is based on the Voigt approximation and can be combined with the Rietveld method as well as with the profile matching (Le Bail fit) procedure. Both the instrumental and sample profiles are supposed to be well described by Voigt functions. To get
reliable sample parameters a good knowledge of the Instrumental Resolution Function (IRF) is needed. Only a phenomenological treatment, in terms of coherent size domains and strains due to structural defects, is performed.
Microstructural Effects of Electromagnetic Stirring Strength and Casting Speed in Continuous Casting of Al Alloy
Authors: Lee Dock Young , Kim Ki Bae , Lee Ho In , Kim Do Hyang
Published: March 2009

Semi-solid forming usually requires feed stock material in form of cylindrical billets with a uniform, globular and fine grain microstructure. These billets are commonly being produced by continuous casting involving agitation of the solidifying melt. The paper will present the development of a horizontal continuous casting machine using circumferential electromagnetic stirring to generate melt flow and shear rate in the continuous casting mould. The machine has been used to study the influence of various process parameters such as electromagnetic stirring strength and casting speed in the production of Al billet with a diameter of 76mm. In order to establish the quantitative relationship between microstructure and the process parameters, the morphology and primary crystal size of billet were observed according to the casting speed and electromagnetic stirring strength. A depth and distance of surface defect on the billet was decreased with increasing a casting speed and a very good smooth surface without any surface defect appeared on the billet produced at a casting speed of 600mm/min. A thickness of the solidifying shell was decreased with increasing the casting speed and the maximum casting speed without a break-out was 600mm/min in horizontal continuous caster designed in this study. Both the size and the aspect ratio of primary crystal were decreased with increasing the casting speed and electromagnetic stirring strength in the range of this study.
Material Spraying Using Electromagnetically Accelerated Plasma Jet
Authors: Tahara Hirokazu
Published: March 2009

In magneto-plasma-dynamic (MPD) arcjet generators, plasma is accelerated by electromagnetic body forces. The MPD arcjet generator can produce higher-velocity, higher-temperature, higher-density and larger-area plasmas than those of conventional thermal plasma torches. Two types of MPD arcjet generator were developed for applications to mullite, zirconia and titanium-nitride spraycoatings. The MPD spray process could successfully form dense, uniform and hard ceramic coatings. In titanium nitride reactive spraying, plasma diagnostic measurement and flowfield analysis were also carried out. A large amount of N and N+ was expected to be exhausted with a high velocity from the MPD generator. Both the electron temperature and the electron number density were kept high at a substrate position compared with those for conventional low-pressure thermal sprayings. A chemically active plasma with excited particles of N+, Ti, Ti+and Ti2+was considered to contribute to better titanium nitride coatings. All coating characteristics showed that the MPD arcjet generators had high potentials for ceramic spray coatings.
Microstructural Evolution and Mechanical Properties of Ultrafine Grained Commercially Pure 1100 Aluminum Alloy Processed by Accumulative Roll-Bonding (ARB)
Authors: Kim Yong Suk , Lee T.O. , Shin Dong Hyuk
Published: March 2009

The ARB process has been carried out up to seven cycles on a commercial purity 1100 aluminum alloy to obtain ultra-fine grains with the average grain size of 500 nm. Microstructural evolution of the ARB processed aluminum alloy was examined by a transmission electron microscopy as a function of accumulated total strain. Mechanical properties including hardness, tensile property, and sliding wear characteristics of the severely deformed Al alloy were also investigated. Grain boundaries of the ARB processed alloy were diffusive and poorly defined after the initial ARB cycles, however they changed to well-defined high angle boundaries with the increase of the accumulated strain. Though hardness and strength of the ARB processed alloy were enhanced significantly, wear resistance of the processed alloy hardly increased. The mechanical properties were discussed in connection with the microstructure.
Deformation Behaviors of Nb Doped Gamma Titanium Aluminides
Authors: Hashimoto Keizo , Matsumoto Rieko
Published: March 2009

In this study, Nb doped γ-TiAl is designed and examined their tensile properties at
elevated temperatures. Small compositional changes cause drastic changes of the mechanical properties at 1273K. In order to clarify the deformation mechanism at elevated temperatures, dislocation structures have been observed using transmission electron microscope (TEM). All of the specimens observed by TEM show that at least two slip systems are operating in each grain. The specimen having relatively lower strength and higher tensile elongations shows more than four operating slip systems in the grains. The specimen having a medium strength shows many super-dislocations and their dissociations that block the other dislocation motions. The specimen having the highest strength shows many deformation twins. These observations suggest that deformation twins become the strong obstacles against moving dislocations at elevated temperatures. The relationships between observed dislocation structures and mechanical properties of γ-TiAl are discussed.
Relationship between Splat Morphology and Property of Plasma Sprayed Alumina Coatings
Authors: Oki Sachio
Published: March 2009

New method for characterization of coating microstructures and for evaluation of coating property by means of surface morphology has been proposed. In this paper, the distribution of shape and dimensions of splat was examined using quantitative analysis of scanning electron microscope images from the surface of spray pattern as well as the surface of coating. Results obtained in this study indicate that it is necessary to analyze the spray pattern as well as the surface morphology in order to estimate the coating property by means of the distribution of splat which composes the coating. Moreover, the splats, which are in the interface between the substrate and the coating, should have the same morphology as those of the coating surface. The relationship between splat morphology and the property of coatings was discussed.
On the Nucleation of Abnormal Grain Growth: A 2D Vertex Simulation
Authors: Weygand D. , Lépinoux J. , Bréchet Yves
Published: March 2009

The conditions for nucleation of abnormal grain growth have been investigated using a 2D vertex simulation allowing for the presence of pinning centers. The topological characteristics of an “almost pinned” structure, compared to the classical grain growth with no pinning force, show a striking correlation between the grain size and the size of the neighbors of this potential abnormal grain. The main finding of this contribution is to stress the crucial importance of pinning particles, and to point to the stochastic nature of the nucleation event in abnormal grain growth.
Dynamic Recrystallization of Zircaloy-4 during Working within the Upper α-Range
Authors: Chauvy Cédric , Barbéris Pierre , Montheillet Frank
Published: March 2009

Compression tests were used to simulate simple deformation paths within the upper a-range of Zircaloy-4 (i.e. 500°C-750°C). The mechanical behaviour reveals two different domains : at low temperatures and large strain rates, strain hardening takes place before flow softening, whereas this first stage disappears at lower flow stress levels. Strain rate sensitivity and activation energy were determined for both domains. Dynamic recrystallization was investigated using the Electron BackScattering Diffraction (EBSD) technique. It appears that the mechanism involved here is continuous dynamic recrystallization (CDRX), based on the increasing misorientation of subgrain boundaries and their progressive transformation into large angle boundaries. At low strains (e £ 0.3), CDRX kinetics are similar whatever the deformation conditions, while higher temperatures and lower strain rates promote recrystallization at large strains.
The Influence of Chemical Composition on the Kinetics of Dynamic Recrystallization of IF Austenite
Authors: Lino Roney Eduardo , Barbosa Ronaldo
Published: March 2009

Dynamic recrystallization, DRX, has become an increasingly important softening mechanism both from fundamental and industrial points of view. During finishing rolling of strips or wire rods, strain is accumulated from pass to pass so that DRX can be triggered. The time need for 50% of material to recrystallize, t50DRX, is strongly dependent on temperature and to a lesser extent on strain rate at which deformation occurs. Few studies report results on the kinetics of DRX and how this softening mechanism can be predicted for a given set of hot deformation conditions, namely strain, strain rate and pass temperature. The purpose of this paper was to investigate how the chemical composition of IF austenite can affect the kinetics of DRX by measuring the apparent activation energy for DRX, QDRX, for alloys with additions of Ti and a combination of Ti-Nb contents. Predicted and measured values of t50DRX, were compared and an empirical expression was proposed to model measured values.
Abnormal Grain Growth in Electrochemically Deposited Cu Films
Authors: Militzer Matthias , Freundlich P. , Bizzotto D.
Published: March 2009

Cu interconnects are essential in advanced integrated circuits to minimize the RC delay. In manufacturing these devices, Cu is deposited electrochemically using a plating bath containing organic additives. The as-deposited nanocrystalline Cu films undergo self-annealing at room temperature to form a micronsized grain structure by abnormal grain growth. Systematic experimental studies of self-annealing kinetics on model Cu films deposited on a Au substrate suggest that the rate of grain size evolution depends primarily on the initial grain size of the asdeposited film. A model for the observed abnormal grain growth process is proposed. Assuming that desorption of the organic additives leads to mobile grain boundaries, the onset of abnormal grain growth is attributed to a sufficiently low additive concentration such that a full coverage of all grain boundaries cannot be maintained. The incubation time of abnormal growth is then a logarithmic function of the initial grain size. The probability to find a growing grain is proportional to the number of grains per unit volume. This assumption is seen to be in good agreement with the experimental observations for subsequent abnormal grain growth rates. The limitations of the
proposed model and the challenges to obtain further insight into the complex microstructure mechanisms during self-annealing are delineated.
A Technique for Real-Time, In-Situ SEM Observation of Grain Growth at Elevated Temperatures
Authors: Fielden I.M. , Rodenburg J.M.
Published: March 2009

We present a novel electron detector and technique permitting orientation contrast images to be generated using back-scattered electron signals. The detector is a modification of the converter plate. It is unaffected by Infra-Red and light photons and invulnerable to the effects of heat. Consequently, the detector is removed as the temperature limiting factor in elevated temperature SEM grain observations. The detector has been successfully applied to an environmental SEM (ESEM) operating in high vacuum mode and has produced good quality video image sequences of hot metal specimens with frame rates between 1 per second and 1 per 30 seconds (largely material dependent). Temperatures attained were up to 850°C, limited by the capability of the hot stage. Although developed for the ESEM the technique is applicable to any SEM provided that adequate measures are taken to manage contamination and heat effects on other microscope components. We
have produced images and short, accelerated video sequences of recrystallisation and grain growth phenomena in steel, aluminium, copper and gold by the new technique. The technique has also successfully imaged phase transformations and high temperature behaviour of microelectronic materials.
In-Situ Observation of Subgrain Evolution during Static Recovery of Cold-Rolled Aluminium
Authors: Gundlach C. , Pantleon Wolfgang , Lauridsen Erik M. , Margulies L. , Doherty R.D. , Poulsen Henning Friis
Published: March 2009

A method for in-situ studies of the dynamics of individual embedded subgrains during
recovery is introduced. The method is an extension of 3DXRD principles for studies of grain dynamics in connection with recrystallisation. It is limited to studies of foils with a sample thickness of 10-100 subgrains due to diffraction spot overlap. The volume evolution during recovery (annealing at 300°C for 181 minutes) of nine individual subgrains in a deformed sample (38% cold rolled Aluminium) is presented.
Microstructural Coarsening during Annealing of Cold Rolled Aluminum
Authors: Xing Q. , Huang X. , Hansen Niels
Published: March 2009

The microstructural evolution during annealing below the recrystallization temperature of a commercial purity aluminum (99wt.% purity) cold rolled to a true strain of 2 has been investigated by transmission electron microscopy concentrating on microstructural and orientational aspects. The deformation microstructure was a typical lamellar structure with extended lamellar boundaries, GNBs (geometrical necessary boundaries), and short interconnecting boundaries, IDBs (incidental dislocation boundaries). The microstructure was divided into regions representing typical rolling texture orientations and regions of other orientations. During annealing the structure coarsened towards an equiaxed structure and it was observed that this coarsening was significantly slower in regions of rolling texture orientations than in regions of other orientations. This difference was discussed based on the characteristics of the deformation structure.
Recrystallization and Texture Development in Hot Rolled 1050 Aluminum
Authors: Alvi Mohammed H. , Cheong Soon Wuk , Weiland Hasso , Rollett Anthony D.
Published: March 2009

The evolution of texture as a function of recrystallization has been characterized for hotrolled AA1050. Samples prepared from hot rolled sheet were annealed isothermally for sufficient time to allow complete recrystallization. The microstructural variation and texture evolution in the samples was observed by automatic indexing of Electron Back Scatter Diffraction (EBSD) patterns in a Scanning Electron Microscope (SEM). The spatial orientation variation within the deformed
microstructure of nucleation, growth and orientations of recrystallized grains was examined. The orientation spread within grains was found to be a useful quantity for partitioning recrystallized and unrecrystallized regions. Also the effect of deformation texture on the evolution and growth of various recrystallization texture components was analyzed. The analysis is aimed at obtaining a correlation between the deformation microstructure, texture development and recrystallization kinetics in the hot-rolled condition. Preliminary results suggest only a weak correlation between the rate of recrystallization and the deformation texture component.
The Effect of Sc on the Extrudability and Recrystallisation Resistance of Al-Mn-Zr-Alloys
Authors: Forbord Børge , Hallem Håkon , Marthinsen Knut
Published: March 2009

As cast and precipitation annealed variants of Al-Mn-Zr-alloys with and without Sc have been extruded in order to study the effect of Sc on the extrudability and the recrystallisation resistance after extrusion and subsequent annealing. Both Zr and Sc form dispersoids, which retard recrystallisation very effectively in many aluminium alloys. However, while Al3Zr often is heterogeneously distributed, a dense and homogeneous distribution of Al3(Sc,Zr)-dispersoids is obtained when Sc is added. This was also the case in these alloys, and the Sc-containing variants consequently displayed a far higher recrystallisation resistance than the Sc-free variants during extrusion and subsequent annealing. Another advantage by adding Sc is that precipitation annealing no longer seems to be necessary in order to obtain a high recrystallisation resistance, as the Sccontaining variants displayed an identical structural stability. The Sc-free alloy, on the other hand, had to be precipitation annealed in order to be able to resist recrystallisation during extrusion. However, an addition of Sc leads to a lower extrudability, as the Sc-containing variants displayed significantly higher extrusion pressures than the Sc-free alloys.
The Effect of Strain Path on the Recrystallisation of an Aluminium Manganese Alloy
Authors: Higginson R.L.
Published: March 2009

The strain path undergone by a material can have a significant influence on the
deformation behaviour, recrystallisation kinetics, grain size and crystallographic texture. To study the influence of strain path, samples of an aluminium-1%manganese alloy have been subjected to a number of strain path changes. These have been achieved using combinations of plane strain and free compression to give strain paths of 0, 90, and 180°. The development of the dislocation substructure resulting from each stage of deformation was studied using Electron Back Scatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Following deformation annealing was carried out to determine the effects of the strain path changes on the recrystallisation kinetics and grain size. Results have shown that the strain path angles cannot be used to satisfactorily describe the material behaviour when mixtures of deformation modes are used.
Texture Development of Ni3Al Thin Foils during Recrystallization and Grain Growth
Authors: Demura Masahiko , Kishida Kyosuke , Xu Ya , Hirano Toshiyuki
Published: March 2009

The texture evolution of 83% cold-rolled Ni3Al foils during recrystallization was examined through heat treatments at 600 °C, 800 °C, and 1000 °C for 30 min. X-ray texture measurements revealed that the texture changed from the as-rolled Goss to a transitional complicated one by primary recrystallization and eventually returned to the Goss texture during grain growth. The SEM-EBSD analysis revealed that the return to the Goss texture was accompanied by the decrease of random boundaries (RBs) and the increase of S1 boundaries. The preferential growth of the Goss-oriented grains was explained by the difference in the grain boundary energy between the RBs and S1, based on the observed grain-orientation maps.
Formation of Grain Boundary Misorientation Spectrum in Alpha-Beta Titanium Alloys with Lamellar Structure under Warm and Hot Working
Authors: Salishchev Gennady A. , Zerebtsov S.V. , Mironov S.Yu. , Semiatin S. Lee
Published: March 2009

Microstructure evolution in alpha-beta Ti-64 alloy samples with lamellar structure deformed to a height reduction of 70% at temperatures between 450 and 800°C has been investigated. The deformation led to a distinctly globularized structure of α- and β-phase in the whole temperature interval. The dependence of globular grain size on deformation temperature is of a linear character up to the temperature of warm deformation at which formation of an SMC structure takes place. Continuous recrystallization was observed in the α-and β-phases. Different types of defects responsible for splitting of α-lamellae such as low and high angle boundaries, shear bands and twins were found. An investigation of boundary misorientation spectra in the α-and β-phases deformed to different strains at 550 and 800°C was carried out. Typical boundary misorientation spectra for single phase metals with the same lattice were obtained. The boundary misorientation spectrum depends weakly on strain and deformation temperature. The results of this study show the importance of transformation of semi-coherent interphase boundaries to non-coherent ones for globularization of lamellar microstructures.
An EBSD Study on Orientation Effects during Recrystallization of Coarse-Grained Niobium
Authors: Sandim Hugo Ricardo Zschommler , Raabe Dierk
Published: March 2009

The recrystallization behavior of coarse-grained niobium depends on the nature of its deformation microstructure. In this regard, a longitudinal section of a high-purity coarse-grained niobium ingot was cold rolled to a thickness reduction of 96% followed by annealing in vacuum at 800°C for 1 h. Metallographic inspection in cold-rolled and annealed specimens was carried out in a field emission gun scanning electron microscope (FEG-SEM). Microtexture was determined by electron-backscattered diffraction (EBSD) coupled to the FEG-SEM. The use this technique has evidenced details of the boundary character and subgrain structure found in partially recrystallized regions. The early stages of primary recrystallization are associated to the presence of high-angle lamellar boundaries found in the cold-worked state. Abnormal subgrain growth has been evidenced as a viable mechanism for nucleation of recrystallization.
Simulation of Spherulite Growth during Polymer Crystallization by Use of a Cellular Automaton
Authors: Raabe Dierk
Published: March 2009

This article introduces a 3D cellular automaton model for the prediction of spherulite
growth phenomena in polymers at the mesoscopic scale. The automaton is discrete in time, real space, and orientation space. The kinetics is formulated according to the Hoffman-Lauritzen secondary surface nucleation and growth theory for spherulite expansion. It is used to calculate the switching probability of each grid point as a function of its previous state and the state of the neighboring grid points. The actual switching decision is made by evaluating the local switching probability using a Monte Carlo step. The growth rule is scaled by the ratio of the local and the
maximum interface energies, the local and maximum occurring Gibbs enthalpy of transformation, the local and maximum occurring temperature, and by the spacing of the grid points. The use of experimental input data provides a real time and space scale.
Anisotropy in Grain Boundary Thermo-Kinetics: Atomic-Scale Computer Simulations
Authors: Upmanyu Moneesh , Trautt Zachary T. , Kappes Branden B.
Published: March 2009

Anisotropy in grain boundary “thermo-kinetics” is central to our understanding of microstructural evolution during grain growth and recrystallization. This paper focusses on role of atomic-scale computer simulation techniques, in particular molecular dynamics (MD), in extracting fundamental grain boundary properties and elucidating the atomic-scale mechanisms that determine these properties. A brief overview of recent strides made in extraction of grain boundary mobility and energy is presented, with emphasis on plastic strain induced boundary motion (p-SIBM) during recrystallization and curvature driven boundary motion (CDBM) during grain growth. Simulations aimed at misorientation dependence of the grain boundary properties during p-SIBM and CDBM show that boundary mobility and energy exhibit extrema at high symmetry misorientations and boundary mobility is comparatively more anisotropic during CDBM. This suggests that boundary mobility is dependent on the driving force. Qualitative observations of the atomic-scale mechanisms in play during boundary motion corroborate the simulation data. p-SIBM is dominated by motion of dislocation-interaction induced stepped structure of the grain boundaries, while correlated shuffling of group of atoms preceded by rearrangement of grain boundary free volume due to single atomic-hops across the grain boundary is frequently observed during CDBM. Comparison of the simulation results with high-purity experimental data extracted in Al indicates that while there is excellent agreement in misorientation dependent anisotropic properties, there are significant differences in values of boundary mobility and migration activation enthalpy. This strongly suggests that minute concentration of impurities retard grain boundary kinetics via impurity drag. Finally, the paper briefly discusses current and future challenges facing the computer simulation community in studying grain boundary systems in real materials where extrinsic effects (vacancy, impurity, segregation and particle effects) significantly alter the microscopic structure-mechanism relations and play a decisive role in determining the boundary properties.
In Situ Investigation of Bulk Nucleation by X-Ray Diffraction
Authors: Larsen A.W. , Gundlach C. , Poulsen Henning Friis , Margulies L. , Xing Q. , Juul Jensen Dorte
Published: March 2009

A new method for in-situ studies of nucleation in bulk metals based on high energy synchrotron radiation is presented. Copper samples cold rolled 20% are investigated. The crystallographic orientations near triple junctions are characterized using non-destructive 3DXRD microscopy before, during, and after annealing for 1 hour at 290°C. This method allows in-situ identification of new nuclei and the deformed material, which spawns the nuclei. Also, since data is acquired during annealing nucleation kinetics can be studied.
Abnormal Grain Coarsening and Its Possible Relationship with Particle Limited Normal Grain Coarsening
Authors: Doherty Roger D. , Hoffman Elizabeth , Hovanec Christopher , Lens Arnaud
Published: March 2009

The prior literature on abnormal grain coarsening (AGC) at low volume fractions (f) of stable second phase particles in high purity Al alloys is reviewed and reanalyzed in the light of developments in modeling particle inhibition of grain boundary migration. With the usual assumptions (i) of incoherent particles that retain their shape on contact with the grain boundaries and (ii) that all the grain boundaries are equally mobile, it appears impossible to account for process of AGC. Normal grain coarsening (NGC) is shown to be less inhibited by the particles than is AGC. This idea is explored using a new but simple model of particle inhibition by curvature removal. The curvature of the smallest grains is always larger than that of the larger grains. Two possible hypotheses to overcome this difficulty are proposed: First the possible change of shape of particles on slowly moving grain boundaries, of grains with near 14 neighbors should, after a small increment of NGC, promote AGC at low values of the volume fraction f. The second hypothesis involves the observed high density of immobile, low angle grain boundaries (LAGBs) found in recent experiments on high purity Al-Fe-Si alloys cast with very coarse grain sizes. These alloys undergo rapid AGC even at higher values of f (> 0.01). These LAGBs are expected to inhibit the shrinkage of many of the small grains, whose loss is the fundamental mechanism of NGC.
Particle Evolution and Grain Growth during Annealing of a Complex Multiphase Al-Sn Triboalloy
Authors: Cerrud Sara M. , Schouwenaars Rafael , Ortiz Armando , Ramírez Edgar I.
Published: March 2009

A fine microstructure stabilised by dispersed particles is an interesting option for increasing the resistance of Al-Sn tribo-alloys without sacrificing ductility. Particle stimulated and continuous recrystallisation allow achieving this goal, but require careful preconditioning of the microstructure to obtain the desired particle distribution. As-cast slabs of Al 12%Sn2%Pb3%Si contain large plates of b-AlFeSi and modified silicon in an aluminium matrix. Sn forms a reticular network which is liquid at conventional annealing temperatures. Experiments show that metastable b-AlFeSi initially coarsens due to Ostwald ripening, but later dissolves and the remainder transforms into FeSiAl12. Silicon partitions to the liquid, allowing the nucleation of numerous small Si-grains.
A New Cooling Nitrogen Gas Generator and Experiments of High Speed Milling of Ti Alloy
Authors: He Ning , Li Liang , Li X.L.
Published: March 2009

Gas cooled cutting is an important branch of green machining technology with its
excellent cooling performance and is used more and more widely in field of machining. A new method of developing cooling gas generator using semiconductor refrigeration is presented in this paper. Then the main principle, structure and performance of the generator are introduced. In addition, the experiments of high speed milling of Ti Alloy using cooled nitrogen gas were conducted and satisfactory results were achieved. These researches show that the new cooling gas generator has a series of merits such as simple structure, excellent performance, handy operation, low cost and significant spreading value etc.
Study on Multi-Dimension Integration Technology of CAPP/PDM
Authors: Jiang Zhao Liang , Li Zheng Qiang , Huang Chuan Zhen , Feng Shi Hong
Published: March 2009

Based on the integration research, one multi-dimension integrated mode of CAPP and PDM was proposed including the integration of knowledge store dimension, knowledge transfer dimension and knowledge application dimension. In the integration of knowledge application dimension, an innovated integration method named key control function module was proposed. In knowledge transfer dimension integration, a recursive model of task and workflow between CAPP and PDM was made. In knowledge store dimension integration, the federal database and the virtual
federal database was described.
Symmetric Fuzzy Prediction of Cutting Force Uncertainty Based on Maximum-Minimum and Mean Values
Authors: Wang W.P. , Hu K.S.
Published: March 2009

In this paper, on the basis of the conception of symmetric fuzzy number and linear
planning theory as well as the maximum-minimum and mean values of the measured cutting force, two fuzzy prediction models of cutting force uncertainty are constructed. The test results show that the proposed fuzzy models can validly predict the variation ranges of cutting force uncertainty for the given cutting conditions, and better express the uncertainty of cutting force than the empirical model from the least square regression.
Studies on Exploiting Further the Potential of High Efficiency Grinding
Authors: Fu Yu Can , Xu Hong Jun , Sun Fang Hong
Published: March 2009

Aiming at the existent problems in the application of high efficiency grinding, some
countermeasures are put forward to further exploit its potential, including the topography optimization design for high efficiency grinding wheel and cooling enhancement technology with jet impingement in grinding zone. The optimization model advanced here can be used to optimize the grinding wheel topography for different grinding processes with the minimum specific grinding energy. The cooling enhancement technology employed in creep feed deep grinding experiment of titanium alloy shows remarkable cooling capability. It is able to steadily control the temperature on workpiece surface at an extremely low lever under 100°C,when the workpiece is seriously burn with the conventional coolant supply. Further studies on the combination of these two countermeasures will not only enable us to increase the available material removal rate to a new lever but also solve the workpiece burn problem for those difficult-to-machining materials in high efficiency grinding.
Fabrication of Ultra-Fine Diamond Abrasive Tools by Sol-Gel
Authors: Liu Juan , Xu Xi Peng
Published: March 2009

In this paper, an experimental study was carried out to fabricate a new kind of ultra-fine diamond abrasive tools by means of sol-gel. The physical properties of the new diamond abrasive tools were evaluated in terms of the bulk density and hardness. The ultra-fine diamond tools were then used to polish granite on a vertical spindle grinding machine. SEM and optical microscope were applied to observe the surface morphologies of the diamond tools and granite. No obvious gathering of ultra-fine diamond grains were found in the new diamond abrasive tools, which exhibited a good wear-resistant ability in polishing. The granite surfaces polished by the new diamond tools were found to be basically smooth except few cracks originally existing in the granite.
Simulation Diagnosis for the Bottleneck of Production Lines and Its Application
Authors: Zhou Jun , Liu Zhan Qiang , Huang Pan Ling , Ai Xing , Deng Jian Xin
Published: March 2009

Traditional bottleneck diagnosis of production lines mainly relies on the designer’s
experience, theoretical calculation or data analysis after practical system run. There are some disadvantages of the traditional bottleneck diagnosis for production lines. Using the virtual manufacturing technologies, a novel Simulation Diagnosis methodology about the Bottleneck of Production Lines (SDBPL) has been presented. With the proposed method, an existed production line is modeled, simulated and analyzed. Its bottleneck is quickly diagnosed by some ways such as
visual simulation results, cycle time, machine utilization and labor utilization. Results reveal that SDBPL can find the location of bottleneck in the practical production lines without wasting practical resource because the entire course of the diagnosis for bottleneck is implemented in virtual environment, and SDBPL is quicker than that of traditional methods as well.
Fine-Grained Access Control of PDM and CAPP
Authors: Feng Shi Hong , Jiang Zhao Liang
Published: March 2009

With the development of Information Technolo gy, distributed integrated system of PDM and CAPP has being focused on by many researchers. To enhance the security access control ability of the integrated PDM and CAPP system, an operational model based on attribute certificate with roles was made. It can prevent unknown entity from accessing to the product data in the integrated system. The function framework of security access control system was analyzed in detail. The
function of fine-grained access control system was presented.
The Architecture of Reliability Information System for CNC Machine Tool in Concurrent Engineering
Authors: Zhang Q. , Liu S.J. , Duan C.Y. , Zhu Y.M.
Published: March 2009

Based on the functional requirement analysis of the compute-aided reliability information system, some concepts are proposed, such as the distributed progressive reliability analysis and the functional decomposition and reconstitution for CNC machine tool. At the same time, the architecture of the CARNC-CE (Computer Aided Reliability Numerical Control for Current Engineering) including physical layer, foundational layer, executive layer, applied layer and illustration layer, is introduced, which provides the general guidance and the frame to realize CNC machine tool reliability analysis system in concurrent engineering.
Structure Dynamic Modification and Optimization for High-Speed Face Milling Cutter
Authors: Tang Wei Xiao , Ai Xing , Wu H.Y. , Zhang Song , Jiang H.
Published: March 2009

Due to the complexity of high-speed milling process by high relative speed and
interrupted cutting, the face milling cutters possess the multi-order modes and the vibrating displacements of the cutting edges under each modes affect adversely both the surface roughness and the life of machine/tool system worse than other structures. In order to improve the stability of milling process, this work focuses on the influence of the variables such as structure geometries and constraint conditions on the eigenfrequencies and modeshapes of cutter. As an example, the
dynamic characteristics of several face cutters are analyzed and optimized by structural dynamic modification (SDM) techniques.
Study and Development of Appliances Recycling Management Information System
Authors: Wang J.Y. , Liu Z.F. , Lv Y.
Published: March 2009

How to dispose and recycle the waste appliances properly and correctly is widely considered to be the focus in modern society. As to this case, in the paper, recycling methods, recycling processes, recycling apparatus and the integration of appliance recycling information have been studied according to different kinds of waste appliances, and finally an integrated appliances recycling management information system (ARMIS) is established based on the ideas studied. The system is an applied software, which is the integration of product information management, recycling process management and recycling product data management, and its purpose is to help recycling enterprises overcome the deficiency of information and management experience in the course of recycling, improve the recycling efficiency of the waste appliances and set a guideline for the operation and management of recycling enterprises.
A Study on the Failure Procedure of the Film-Substrate Interface Based on the Laser Scratch Testing Technique
Authors: Feng Ai Xin , Zhang Yong Kang , Xie H.K. , Cai Lan
Published: March 2009

The interfacial adhesion between thin film and substrate is often the predominant factor and chief target in determining the performance and reliability of thin film/substrate system. A new technique of laser scratch testing technique has been presented by the authors of the article to characterize the interfacial adhesion between film and substrate, which synthesizes the advantages of traditional scratching technique and laser measure technique. The failure procedure is studied
detailedly in the article. On different failure step of the film/substrate system, there are different characteristic s of stress and strain, as well as the characteristic of thermal lensing effect, which can be used as the distinguishing rule of the bonding state of the film/substrate system.
Comparative Experiments for Different End Mills of Indexable Inserts with 3-D Chip Breaker
Authors: He Y. , Yao Zheng Qiang
Published: March 2009

End mills are very widely used in machining metal. In this paper, based on analysis of three different end milling indexable inserts with 3-D chip breaker, the influence of different chip breaker on cutting force, chip deformation and machined accuracy are studied by comparative experiments. The results show that the cutting effect of end mills with indexable inserts can be improved by optimization of 3-D chip breaker and suitable for different machining condition.
An Investigation into Surface Roughness of Burnished Hypereutectic Al-Si Alloy Based on the Taguchi Techniques
Authors: Han Li Fa , Xia Wei , Li Yuan Yuan , Chen Wei Ping
Published: March 2009

This paper presents an investigation on the surface roughness of burnished hypereutectic Al-Si alloy ¾ a widely used light-weight and wear resistant material in automobile, electric and aircraft industries. Based on the techniques of Taguchi, an orthogonal experiment plan with the analysis of variance (ANOVA) is performed and a second-order regressive mathematical model is established. Meanwhile, the influence of process parameters on surface roughness and its mechanism are discussed. From the experiments, it is found that burnishing process is effective to decrease surface roughness of hypereutectic Al-Si alloy components, in which, all input parameters have a significant effect on the surface roughness. To achieve a small surface roughness, the optimum process parameters are recommended.
Process Analysis on a Special Projection Welding with Coupled FEM
Authors: Luo A.H. , Chen Guan Long
Published: March 2009

Projection welding is a variation of electric resistance welding with the dynamic changes of the flow paths for heat and electrical properties with changing temperature caused by the large plastic deformation with collapse of projection. The common standards of projection welding are AWS, IIW and Harris& Riley which have been established and in use for some time. All these standards have the slots located under the projection. However, the standard proposed in this paper
researches on is a special one with the slots designed on the two sides of the projection. A comprehensive thermal-electrical-mechanical analysis was performed to quantitatively simulate the projection welding of the special standard by a coupled finite element method. The electrical, thermal and mechanical aspects of the projection welding processes such as the projection collapse mechanism, the nugget formation process and the effects of different electrode forces were discussed in this paper.