bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Stress State of Low-Frequency Vibration Cutting Process Based on Finite Element Simulation
Authors: Gu Li Zhi , Du Wei Wen , Wang Jian Tao , Qu Shao Kui , Huang Yan Hua
Published: May 2014

Proposed a concept, “cutting degree” as one of the parameters indicating the surface characteristics of the machined layer integrity. According to material nonlinearity, geometric nonlinearity, thermal coupling theory, established models of the vibratory cutting simulation, constitutive J-C model, shear model, boundary conditions, made finite element simulation of low-frequency vibration cutting by using software. Accessing to a visualization process, which is the change of material stress state in local area of the workpiece in cutting process. Analyzed the change of material stress states in local area of the workpiece, between low-frequency vibration cutting and non-vibration cutting machining process, other cutting parameters being equal. It is found that the values of cutting degree were apparently different in vibration cutting from those in non-vibration cutting. Contrasting experiments were done and SEM was observed of the machined surfaces. Findings of the experiment supported the simulation and to some extent validated the feasibility of the vision of 'cutting degree' as a term for expression of vibration cutting feature.
Design of an Intelligent Bedsore Treatment System Base on LabVIEW
Authors: Su Liang Yu
Published: May 2014

Bedsore is a common disease for long-term bedridden patients,electronic treatment instruments can effectively prevent the occurrence of bedsore.In this paper,stress sensor and micro-controller are used to sample pressure signal of each part of the body and send the signal to PC by RS232.LabVIEW virtual instrument is designed to analyze the measure pressure data,and estimate the state of every parts of the human body that have been continuously pressed.Then the LabVIEW instrument will send control signals to the corresponding pumps of the mattress.This instrument can prevent human skins being pressed too long in part areas.
Development of Aircraft Used Wires for General Purpose and a Study on the Application
Authors: Liu Cong , Yan Li
Published: May 2014

This paper makes an overview of the development of the wires for general purpose in aircraft,and an introduction of two types of prevalent wires today: XL-ETFE extruded insulated wires and PTFE/PI tape wrapped insulated wires. A performance contrast of these two types of wires is made from electrical, physical, environment resistance and weight aspects. A study on application of these wires in aircraft is also made, and finds the potential of the PTFE/PI tape wrapped insulated wires in weight saving and design optimizing.
Optimization of Double Pivot Suspension Kingpin Axis during Steering
Authors: Shi Tian Ze , Wang Deng Feng , Chen Shu Ming , Dong Hong Liang
Published: May 2014

A double pivot suspension used for in-wheel motor electric vehicle was designed, and the virtual prototype model of the suspension assembly was build. The suspension parameters changed greatly during steering. In order to solve this problem, this paper proposed a non-linear response surface model to fit the relationship of suspension parameters and design variables. An optimization scheme was designed based on the response surface model. The suspension performance was improved significantly using optimized variables.
Research on the EDM Equipment and the Machining Technology of the Precision Micro-Hole
Authors: Cai Yan Hua , Liu Jian Yong , Ding Lian Tong , He Shi Shan , Zhang Shi Fu
Published: May 2014

The main structure and key components of the precision EDM equipment are analyzed and researched in this paper. Key components such as main structure, A-axis, W-axis and R-axis are designed. Aimed to machine several kinds of diameters on a work piece, an on-line electrode milling method is studied. And then test this method on an EDM machine. Based on the test results, the functional relation between diameters and the wears of the electrode is confirmed by the least square method. According to this function, the efficiency of the EDM machining for the precision micro-holes is improved.
Experimental Design for Characteristics of Fiber Temperature and Strain
Authors: Ye Wei Wen , Wang Lu , Shi Qing Guo , Lei Xue Qin , Peng Bao Jin
Published: May 2014

This thesis analyses the problems that exist in the fields of fiber-sensor experiment, and real-time draw the diagram of creating a flat about optics-intervene, using computer and camera to replace the traditional observation which are with the eyes to calculate the number of the moving stripes, and using the combination of temperature sensor and computer to replace the traditional thermometer. At the same time, the computer can collect the temperature and the number of moving stripes, and real-time draw the diagram of the temperature and the number of stripes, or draw the relationship of the tension and the number of moving stripes. Experimental results show that the system is stable and reliable, as well as having an age-feeling much more.
Discussion on the Application of Activity-Based Costing in Virtual Manufacturing Cell Mode
Authors: Lv Jie , Xiong Ling Ling , Han Wen Min
Published: May 2014

As a new development of cell manufacturing mode, virtual manufacturing cell (VMC) has complied with the new production organization requirements of current production efficiency and production flexibility improving synchronously, and it presents new characteristics in terms of cost accounting and cost control. Traditional cost methods present some shortcomings in VMC mode. For these situations, this paper discusses the advantages of activity-based costing (ABC) in VMC mode and improves traditional ABC to better meet the cost accounting requirements of VMC. Finally, an example is used to illustrate the basic use of the improved ABC in VMC mode.
Microhardness Analysis of Laser Cladding CBN Coating on the Surface of Titanium Alloy
Authors: Zhao Shu Guo , Yao Xiao Min , Li Rui
Published: May 2014

The Cubic boron nitride (CBN) coating are prepared by laser cladding on the TC11 surface.The hardness of cladding coating were researched by means of mechanical property testing.The result indicated that the coating micro-hardness increases with increasing laser power when the other parameters are fixed.With the laser power increasing,Injection of energy increases,The reinforced phase increased,microhardness along with it enhancement.With the increase of the scanning speed within chose, the microstructure of the cladding layer changes tiny and uniform,the microhardness were increased,The hardness was increased greatly which after Laser hardening. The maximum values of them are as about five times as that of the substrate.
An Improved Multi-Label Classifier Chain Derived from Binary Relevance
Authors: Guo Tao , Li Gui Yang
Published: May 2014

In multi-label classification, each training example is associated with a set of labels and the task for classification is to predict the proper label set for each unseen instance. Recently, multi-label classification methods mainly focus on exploiting the label correlations to improve the accuracy of individual multi-label learner. In this paper, an improved method derived from binary relevance named double layer classifier chaining (DCC) is proposed. This algorithm decomposes the multi-label classification problem into two stages classification process to generate classifier chain. Each classifier in the chain is responsible for learning and predicting the binary association of the label given the attribute space, augmented by all prior binary relevance predictions in the chain. This chaining allows DCC to take into account correlations in the label space. Experiments on benchmark datasets validate the effectiveness of proposed approach comparing with other well-established methods.
Measuring Influence and Impact by Complex Network
Authors: Zhang Zheng Chang
Published: May 2014

This paper built two kinds of networks:co-author network and competition network and set up a system of influence measurement to determine who is most influential in the network.To evaluate the influence of co-authors, this paper introduced three norms: degree centrality, closeness centrality and betweenness centrality. Then, entropy value method was applied to get the relative weight of norms and establish co-author influence measurement model by the weighted sum of the three norms as influence marks. Meanwhile, the number of times players competed with each other among 10 tennis players in nearly 20 years was chosen to build our network. Because same as the co-author network, the competition network is undirected, we employ same algorithm to rank tennis players and analyze the first three players' competition relationship.
Statistical Analysis of Dynamic Properties of Solid Carbide End Mill
Authors: Yi Yi Kai , Gang Tie Qiang , Zhang Zhi Qiang
Published: May 2014

By three-dimensional milling simulations of Aviation Aluminum 7050-T7451 with metal cutting finite element analysis software AdvantEdge FEM, milling force data was obtained and amplitude-frequency characteristics was achieved through Fourier transformation of milling forces. According to mathematical statistical analysis of milling force data, we illustrates that the high-speed milling is a multi-blade interrupted cutting process and the tool vibration is a random vibration. Correlation functions and power spectral density functions of milling force and displacement were calculated in terms of signal processing discipline.
Surface Roughness Measuring Based on the Theory of Fractal Geometry
Authors: Wu Ding Gui , Gang Tie Qiang , Fan Xian Guang , Wu Jing Lin
Published: May 2014

Conventionally several statistical roughness parameters are used for describing surface roughness. But instruments with different resolutions and scan lengths yield different results of these statistical parameters for the same surface. Due to the limitations of traditional characterizing methods, the fractal characteristic of the rough surface is studied in this paper. A surface roughness measuring instrument is redesigned based on the on theTalysurf5Μ for both hardware and software. The signal conditioning process of the inductance sensor is analyzed. The grinding samples measurements indicate that work-piece surface presents fractal characteristic, and larger roughness level Ra corresponds to larger fractal dimensionDbut smaller characteristic length scaleG. The fractal characterization of surface roughness, to some extent, overcomes the deficiencies of conventional evaluation method, and shows higher sensitivity and accuracy.
Wireless Sensor Networks Based on a New Block Encryption Algorithm
Authors: Wang Hai Yan
Published: May 2014

In the power system for wireless sensor networks special working environment. The net works in special environment, the node, with the characteristics of small bulk, the little memory resource, lower operation and little energy, can not be reused, the wireless network thus has special requirements for the security. Based on the characteristics of wireless sensor networks was proposed based on chaotic key block encryption algorithm. Based on the characteristics of wireless sensor networks was proposed based on chaotic key block encryption algorithm. Chaos expansion algorithm uses integer keys, the improved RC6 encryption plaintext shift operation, use cipher text feedback modify the control parameters to the relevant key and cipher text, effective against plaintext attack. The simulation results show that the security of the algorithm is high and fit for WSN.
Theoretic Analysis on Methods for One-Phase to Three-Phase Power Supply Transformation
Authors: He Guang Quan , Guo Wen Rui , Zhu Yong Qiang , Wen Ya Feng
Published: May 2014

The paper focuses on the review of methods of one-phase to three-phase transformation. Analysis of the demand of one-phase/three phase transformation is conducted. L-C splitting circuit, one-phase to three-phase transformation based on balance transformer, and one-phase to three-phase converter are three common methods of transformation, of which principle analysis and comparison of advantages and disadvantages have been conducted. This paper also discusses problems underlying the existing methods and proposes the possible future development.
Data Conversion from BPA and PSASP to the Third Party Software Based on Template Matching Algorithm
Authors: Ye Qing , Zhu Yong Qiang
Published: May 2014

With the development of electric power system, the use of one single electric power simulation software about large power grid can't meet the needs of the actual research any more. As the data of PSASP, BPA and other software can't be universal, developing a data interface program to realize data file sharing is of great concern. In this paper, based on the template matching method, power system network model and the control model itself of different software are compared and studied, and the template database was designed according to the results of the analysis. Data convert from BPA and PSASP to the third party software is realized.
Product Name Recognition for Informal Text: Exploring Features
Authors: He Tao , Liu Juan
Published: May 2014

Product name recognition refers to locate the name of product in text automatically. We built a conditional random field to recognize product name from forum posts and explored various features to compare their impact on the performance. These features include not only traditional features used for NER but also distributed word representations which are novel features obtained from new area of machine learning.
On Two First Order Reliability Methods for Computing the Non-Probabilistic Reliability Index
Authors: Qiao Xin Zhou
Published: May 2014

The two first order reliability methods (FORM) for computing the non-probabilistic reliability index, namely the mean-value method and the design-point method, are investigated. A performance comparison is presented between these two methods. The results show that: (1) the value of the reliability index of the mean-value method depends on the specific form of the limit state function, whereas the value of the reliability index of the design-point one does not;(2) the design-point method should be preferentially used in structural reliability assessment. The conclusions are verified by a numerical example.
Study on Optimization of Signal Transmission Technology Based on Layered Source with Superposition Coding
Authors: Liu Yue Liang
Published: May 2014

The optimization of wireless multipoint multimedia broadcasting system layered source transmission was studied and analyzed. The introduction of continuous layered source with superposition coding model infinite layer in this article, the optimal inter-layer power distribution function is given by variation method, then an average per user up to speed is obtained. In the simulation, the LSSC which introduces a layered source coding scheme compared with the traditional CB Scheme. LSSC transmit multiple data streams to meet different end user channel conditions is verified by the results. The problem of system performance loss due to channel asymmetry between the center of the cell edge users and users bring have been effective solved.
Design and Implementation of Online Shopping System Based on J2EE
Authors: Hong Ying
Published: May 2014

Shopping online is being a kind of mainstream e-business model with the development of internet. The necessity of establishing an online shopping system was proposed. This paper makes a specific analysis on the key problems and implementation method of online shopping system. A brief introduction of J2EE structure and EJB technique is given in this paper. The method based on J2EE component technique was used in design and implementation of this online shopping system. Because of using J2EE multi-layer architecture technique, this system has a good portability, good scalability and high reliability.
The Application of IBE Encryption Scheme in Grid Environments
Authors: Bai Qing Hai , Zheng Ying , Zhao Lin Na
Published: May 2014

The computing service and security service are separated in current Grid system, but the data transmission of the system has to cross unsafe public channel. This makes the results computing by the Grid system may be stolen or destroyed by artificial or non-artificial factors in transmission process. So the Grid system has secure requirements of confidential communication, data integrity and non-repudiation. For these requirements, this paper puts forward an identity-based encryption scheme and realizes the function of confidentiality, Integrity, Key Update and non-repudiation. To test the security of the proposed scheme, the authors make a detailed analysis in random oracle model and prove the security of the scheme equivalents to the difficulty of the bilinear Diffle-Hellman problem. So our scheme is proved to be correct.
Occurrence of Dynamic Alpha-Phase Nucleation in Ti-5553 during Hot Deformation
Authors: Fall Ameth Maloum , Piot David , Montheillet Frank , Andrieu Sandra
Published: May 2014

This paper discusses the microstructural changes during hot deformation, mainly dynamic nucleation and growth of a precipitates, occurring in the b metastable titanium alloy Ti-5553 (Ti–5Al–5Mo–5V–3Cr–0.5Fe). The effect of process variables on flow response and microstructure evolution during hot working of the alloy with initial bimodal microstructure was established using isothermal hot-compression tests. Testing was conducted at 4 strain rates between 0.001 and 1 s−1 and 5 temperatures between 720 °C and 850 °C, on material with prior b grain size of 450 μm, a nodular size of 3 µm and a known primary a-phase fraction. All flow curves exhibited a peak stress followed by moderate flow softening in the two-phase domain. Flow softening was interpreted in terms of deformation heating and substructure or texture evolutions. The dependence on strain rate and temperature of the kinetics of dynamic a-phase nucleation during straining is complex and appears to be of second-order importance compared to the effects of strain. This suggests that the nucleation and growth of a phase in the temperature range between 720 °C and 990 °C results from a mixed-mode displacive-diffusional transformation, similar to the austenite / ferrite transformation above the Ae3 temperature reported by some authors.
Effect of Plastic Deformation on a Dispersion of Omega-Phase and Mechanical Properties of an Al-Cu-Mg-Ag Alloy
Authors: Gazizov Marat , Zuiko Ivan , Kaibyshev Rustam
Published: May 2014

Effect of cold rolling prior to ageing on a dispersion of secondary phases and mechanical properties at room temperature for an Al-5.6Cu-0.72Mg-0.5Ag-0.32Mn-0.17Sc-0.12Zr (wt. %) alloy, which was solution treated and water quenched initially, was examined. It was shown that cold working leads to significant increase in density of lattice dislocations that induces the formation discrete agglomerates of the θ′-phase on the {100} planes. Strain of 7% provided increased aspect ratio (length to thickness) of plates that leads to moderate increase of strength. Imposing of higher strains leads to increased lattice dislocation density and the formation of deformation-induced boundaries. Precipitation of the coarse particles of secondary phases on these boundaries takes place. The high yield stress (YS) of 535 MPa and ultimate tensile strength (UTS) of 570 MPa, were attained after cold rolling with a reduction of 80% followed by ageing at 190°C for 2 h. The effect of plastic deformation prior to ageing on the precipitation behavior and strengthening of Al-Cu-Mg-Ag alloy is discussed.
Thermomechanical Ageing of Copper-Clad Aluminum Wires Submitted to Creep Test Conditions
Authors: Gueydan Antoine , Hug Eric , Domengès Bernadette
Published: May 2014

Creep tests were performed on copper-clad aluminum wires at 423 K and different stresses to cover potential operating load ranges in automotive industry. The lifetime of the wires is strongly dependent on the existence of an initial heat treatment and on the applied stress. It can be correlated with the formation of the three intermetallics Al2Cu, AlCu and Al4Cu9 identified by TEM diffraction. All results are discussed to understand mechanisms that could lead to the embrittlement of copper-clad aluminum wires by creep.
Determination of Preferred Morphology of Self-Accommodating Martensite in Ti-Nb-Al Shape Memory Alloy Using Optical Microscopy
Authors: Ii Masatoshi , Tahara Masaki , Hosoda Hideki , Miyazaki Shuichi , Inamura Tomonari
Published: May 2014

The preferred morphology of self-accommodation (SA) microstructure in a Ti-Nb-Al shape memory alloy was investigated by the evaluation of the frequency distribution of the habit plane variant (HPV) clusters using in-situ optical microscopy. The observed HPV clusters were classified into two different types; one is the cluster connected by the {111}o type I twin (Type I) and the other is connected by the <211>o type II twin (Type II). The total fractions of the Type I and Type II clusters were 52% and 48%, respectively. The incompatibility at junction planes (JPs) of the two clusters was almost the same among these clusters. However, most of the larger martensite plates (> 50μm) formed Type I cluster at the later stage of the reverse martensitic transformation, i.e., at the early stage of the forward transformation upon cooling. The ratio of the fraction of Type I and II is almost 2:1 at the early stage of the forward transformation.
Compression of Single-Crystal Micropillars of the Γ Intermetallic Phase in the Fe-Zn System
Authors: Inomoto Masahiro , Okamoto Norihiko L. , Inui Haruyuki
Published: May 2014

The deformation behavior of the Γ (gamma) phase in the Fe-Zn system has been investigated via room-temperature compression tests of single-crystal micropillar specimens fabricated by the focused ion beam method. Trace analysis of slip lines indicates that {110} slip occurs for the specimens investigated in the present study. Although the slip direction has not been uniquely determined, the slip direction might be <111> in consideration of the crystal structure of the Γ phase (bcc).
Polymer/Metal Joining with Carbon Fibers with High Resistance to Pull-Out Induced by Huge Friction Force Generated by Extremely Broad Total Interface Area
Authors: Inui Shigehito , Shiraishi Kazuma , Ishii Sho , Kasai Atsushi , Miwa Noriyoshi , Kanda Masae , Nishi Yoshitake
Published: May 2014

Although welding, blazing, rivet connecting and glue are typical joint methods for aerospace materials, they mostly reduced the materials strength. In order to prevent the fracture at joint part between aluminum (Al) and carbon fiber reinforced polymer (CFRP) utilized for airplanes, a new method with extremely large friction force by broad interface of carbon fiber (CF:6 μm-diameter) coated by nickel (Ni) was suggested for a joint (Al/NiCF/CFRP) of CFRP and Al. The Al/CFRP joint method using nickel-coated carbon fiber improved the Charpy impact value, as well as tensile strength.
Investigation of Biodegradable Composite Coated Magnesium Alloy Using Optical Coherence Tomography
Authors: Johnson Ian , Shahidul Islam M. , Park B. Hyle , Liu Hui Nan
Published: May 2014

Optical coherence tomography (OCT) was used to characterize poly (lactic-co-glycolic acid) (PLGA) and nanophase hydroxyapatite (nHA) / PLGA coatings on magnesium (Mg) substrates before and after immersion in revised simulated body fluid (rSBF) under standard cell culture conditions. The OCT images clearly showed: the surface of the coatings, the metallic surface underneath the coatings, the presence of a dispersed phase within the polymer matrix, and defects and structural changes to the coatings. This study demonstrated the potential utility of OCT for performing quality assurance tests and for tracking the physical effects of degradation upon biomedical implants due to its ability to rapidly render easily interpreted images of sub-surface structure in a non-destructive manner.
Thermodynamic Modeling and Experimental Measurement of Precipitation Formation during Dynamic Recrystallization for Magnesium Alloys
Authors: Kabir Abu Syed Humaun , Su Jing , Sanjari Mehdi , Jung In Ho , Yue Stephen
Published: May 2014

Magnesium alloys have low formability at room temperature associated with its hexagonal closed pack structure. Formation of precipitates during deformation may pin the grain boundary and reduce the final grain size, which literally means the improvement of formability. The aim of this study is to design magnesium alloys that are capable of forming precipitate during hot deformation. Thermodynamic modeling software, FactSage, has been used to design Mg-Al-Sn alloys based on forming target Mg2Sn precipitate at hot deformation temperatures between 250 and 350oC. Uniaxial compression at elevated temperatures has been performed to simulate the hot deformation behaviour as well as to enhance the formation of precipitates. Strain rates used in this study were in the range of 1.0 to 0.001s-1 for a constant deformation degree of 90%. It was found that the formation of precipitate depends on deformation temperature and strain rate. Measured amounts of precipitate were compared with the calculated equilibrium results from FactSage.
Tempering of Direct Quenched Low-Alloy Ultra-High-Strength Steel, Part I – Microstructure
Authors: Kaijalainen Antti , Pallaspuro Sakari , Porter David A.
Published: May 2014

The direct quenching of low-carbon steel has been shown to be an effective way of producing ultra-high-strength, tough structural steels in the as-quenched state without tempering. However, in the present study, the influence of tempering at 500 °C has been studied in order to evaluate the possibilities of widening the range of strengths that can be produced from a single base composition. The chosen composition was 0.1C-0.2Si-1.1Mn-0.15Mo-0.03Ti-0.002B. In order to compare direct quenching with conventional quenching, two pre-quench austenite states were studied: a thermomechanically rolled, non-recrystallized, pancaked austenite grain structure and a recrystallized, equiaxed grain structure. Quenched and quenched-and-tempered microstructures were studied using FESEM and FESEM-EBSD. The as-quenched microstructures of the reheated and quenched and direct quenched specimens were fully martensitic and martensitic-bainitic, respectively. In both cases, tempering made the needle-shaped auto-tempered carbides of the as-quenched materials more spherical. In the case of the direct quenched (DQ) material, tempering led to a notable increase in the size of the grain boundary carbides. Prior austenite grain size and effective grain size after quenching were larger in the case of reheated and quenched material (RQ). Tempering had no effect on effective grain size. The crystallographic texture of the DQ material showed strong {112}<131> and {554}<225> components. The RQ material also contained the same components, but it also contained an intense {110}<110> and {011}<100> components. The effects of these microstructural changes on tensile, impact toughness and fracture toughness are described in part II.
Microstructural Evolution of AA5052 Alloy Sheets in High-Speed Rolling
Authors: Kazaoka Toru , Zhou Dan Hua , Kataoka Noriaki , Matsumoto Ryo , Utsunomiya Hiroshi
Published: May 2014

It is known that grain refinement improves balance of strength and ductility of materials. As a technique to obtain fine-grained microstructure, dynamic recrystallization can be used in industrial processes. The authors reported that fine grains appear beneath the surface of Al-Mg alloy sheet by high-speed rolling. In this study, rolling conditions to form fine recrystallized microstructure were investigated. AA5052 alloy sheets were rolled at 500 m/min, 1000 m/min or 2000 m/min with thickness reduction of 30%, 50% or 70% at 473 K, 523 K, 573 K or 623 K. After the rolling, the sheets were water-quenched immediately. It is found that the critical strain for dynamic recrystallization is very large. For example, when the sheets are rolled at 1000 m/min and 623 K, thickness reduction greater than 76% is required for dynamic recrystallization.
Strengthening and Toughening Mechanisms in Martensitic Steel
Authors: Kennett Shane C. , Findley Kip O.
Published: May 2014

Low carbon martensitic steels are often produced by reaustenitizing and quenching (RA/Q). Direct quenching (DQ) has gained interest in the past few decades and requires quenching immediately after working above or below the austenite recrystallization temperature to form martensitic microstructures. In the current study, microalloyed ASTM A514 steel is used to produce martensite from either equiaxed or pancaked prior austenite grain (PAG) microstructures. The equiaxed PAG conditions simulate microstructures produced by RA/Q and the pancaked PAG conditions simulate microstructures produced by controlled rolling (CR) before DQ. Controlled rolling followed by DQ was simulated with double hit compression in a Gleeble® 3500. The prior austenite grain size (PAGS) was varied between 9 and 75 μm prior to controlled rolling. The strengthening and toughening mechanisms are being investigated in the as-quenched (AsQ), low temperature tempered (LTT: 200 °C), and high temperature tempered (HTT: 600 °C) conditions. The equiaxed PAG condition has a Hall-Petch (H-P) relationship between yield strength (or microhardness) and PAGS in the AsQ condition. There is not a H-P relationship between PAGS and microhardness in the CR-DQ conditions. The CR-DQ conditions generally exhibit higher microhardness than the RA/Q conditions with similar PAGS, with the most significant differences in the larger PAGS conditions. Toughness was only measured in the equiaxed PAG conditions. The smallest PAGS has the lowest ductile-to-brittle transition temperature (DBTT) with the highest strength in the AsQ and LTT conditions. The smallest PAGS has the lowest DBTT and the lowest strength in the HTT condition.
Hybrid Structure of TiO2 Nanofiber and Nanoparticle for Dye-Sensitized Solar Cells
Authors: Kim Ji Sun , Shim Seong Cheol , Hwang Tae Hwan , Choi Won Youl
Published: May 2014

Hybrid structure of TiO2 nanofiber and nanoparticle as a photoelectrode was very attractive in dye-sensitized solar cells (DSCs) because TiO2 nanoparticle provided a high specific surface area to adsorb the N719 dye and TiO2 nanofiber was a direct path to transfer photoelectron from dye to electrode. TiO2 nanofiber film was prepared with titanium-tetraisopropoxide (TTIP) and polyvinylpyrrolidone (PVP) based precursor by electro-spinning process. To fabricate the hybrid structure, TiO2 nanoparticular paste was screen printed on the TiO2 nanofiber film. Electrospun TiO2 nanofiber film and screen printed TiO2 nanoparticular film were combined in layer by layer method. These films were observed as an anatase phase by X-ray diffraction pattern. Thickness and diameter of TiO2 nanofibers were ~5μm and ~400nm, respectively. Thickness and particle size of TiO2 particles were ~5μm and ~20nm, respectively. Compared to conventional DSCs, higher short circuit current densities (Jsc) of 6.47 mA/cm2 and higher power conversion efficiency of 3.06 % were measured in DSCs having hybrid structure of TiO2 nanofiber and nanoparticle. Electrochemical impedance spectroscopy (EIS) was observed to understand an electron transfer and life time.
Contributions of Grain Boundary Sliding and Solute Drag Creep to High-Temperature Ductility in Fine-Grained Polycrystalline 5083 Alloys
Authors: Mizuguchi Takashi , Ito Tsutomu , Kimura Kota , Tanaka Yasuhiro
Published: May 2014

In this study, the high-temperature ductility of a fine-grained, polycrystalline 5083 solid solution alloy was investigated. The composition of the alloy in mass% was Al–4.5 Mg–0.68 Mn–0.19 Fe–0.13 Si–0.11 Cr. Grain refinement was effectively achieved in the stir zone by a friction stir process, and the grain size could be reduced to 3.7 μm. Tensile tests were performed at temperatures ranging from 643 to 743 K and strain rates ranging from 0.001 to 0.1 /s. The stress–strain curves showed that the flow stress continuously decreased until it reached a maximum value of stress and fractured after the initial strain hardening occurred. The value of elongation-to-failure was more than 100% when temperatures were greater than 693 K. The high ductility observed at this point can be referred to as superplastic-like elongation. This phenomenon has been reported in some Al–Mg alloys. The experimentally determined stress exponent (n value) and activation energy for deformation were about 2.5 and 123 kJ/mol, respectively. These results suggest that the grain boundary sliding, accompanied by solute drag motion of dislocations, was a rate controlling process for deformation.
Approvement of “Tension-Compression” Technique Developed for Physical Simulation of Multistage Metal Plastic Deformation Processing
Authors: Bezobrazov Yuriy A. , Kolbasnikov N.G. , Naumov Anton A.
Published: May 2014

There are a number of techniques for physical simulation of multistage metal plastic deformation processes. Analysis of these techniques in terms of stress-strain state schemes is presented. The purpose of described research is to compare microstructure and mechanical properties of two pipe steels processed by laboratory rolling mill with microstructure and mechanical properties of the same steels processed by thermomechanical simulator Gleeble-3800 with four different mobile convert units (MCU): MaxStrain, Torsion, HydraWedge and Pocket Jaw. Obtained results clearly show that proposed "tension-compression" technique developed for Gleeble Pocket Jaw MCU is theoretically and experimentally proved and can be successfully used for simulation of complex multistage metal plastic deformation processes, such as rolling, forging, stamping, etc.
Effect of Cold Rolling on Microstructure and Mechanical Properties of an Al-Mg-Sc-Zr Alloy
Authors: Kulitskiy Vladislav , Malopheyev Sergey , Kaibyshev Rustam
Published: May 2014

The microstructural evolution and mechanical properties of an Al-5.4Mg-0.4Mn-0.2Sc-0.09Zr alloy subjected to cold rolling with a total strain up to ~1.6 was studied using high resolution EBSD analysis and TEM. It was shown that cold rolling induces elongation of initial grains and the formation of deformation bands along rolling direction in addition to dramatic increase in density of lattice dislocations. Two types of deformation bands evolve. Deformation bands initially bounded by low-angle boundaries (LABs) with misorientation higher than 2o and spacing ranging from 0.8 to 4 μm gradually transform to lamellas delimited by high-angle boundaries (HABs). Thin deformation bands delimited by LABs with misorientation of 2o or less evolve within these coarse bands. First type of deformation bands is subdivided due to mutual intersection with second order deformation bands or shear bands to elongated crystallite evolving to micron scale grains with strain. The thin deformation bands may be also subdivided to nanoscale crystallites. It was shown that the formation of well-defined deformation bands yield very high anisotropy in strength and ductility, while a strong increase in lattice dislocation density with strain diminishes this anisotropy.
Effect of Cold Rolling on Microstructure and Mechanical Properties of a Fe-23Mn-0.3C-1.5Al TWIP Steel
Authors: Kusakin Pavel , Belyakov Andrey , Kaibyshev Rustam , Molodov Dmitri A.
Published: May 2014

Effect of cold rolling on the microstructure and mechanical properties of a Fe-23Mn-0.3C-1.5Al (in wt. %) TWIP steel with an initial grain size of 24 μm was studied. Extensive deformation twinning occurred upon reduction by rolling. The volume fraction of the deformation twins attained about 0.2 at a reduction of 20%. Then, the intensity of deformation twinning gradually decreased with increasing the total rolling reduction. The average twin thickness of about 20 nm remained unchanged, although the distance between twins progressively reduced with increasing strain. The deformation banding was observed after a reduction of 60%. The thickness and volume fraction of microshear bands increased with increasing rolling reduction. The cold rolling led to significant strengthening of the steel that is accompanied by a drop on ductility. The yield stress (YS) increased from 235 MPa in the initial state to 1400 MPa after cold rolling with a reduction of 80%, whereas the elongation to failure decreased from 96% to 4%, respectively.
Phase Transformations of TIMETAL-18 as a New Titanium Alloy with Bimodal Microstructure
Authors: Lebrun E. , Svec Peter , Nowak S. , Denand B. , Millet Y. , Prima Frédéric
Published: May 2014

In this work, we have investigated the microstructural evolutions and the phase transformations of a new near-beta alloy with a nominal composition of Ti-5.5Al-5V-5Mo-2.4Cr-0.75Fe-0.15O (weight percent), the TIMETAL 18 [here after called Ti-18]. The complete microstructural state of the Ti-18 during heat treatments, from as quenched metastable state, has been first investigated. The phase transformations have been studied by combination of X-ray diffraction analysis, metallurgical observations and electrical resistivity measurements. From a series of isothermal treatments, the first complete TTT diagram has been then established displaying three C-curves corresponding to different precipitation domains for alpha phase.
Wear Properties of Ti-6Al-4V/Ti-29Nb-13Ta-4.6Zr Combination for Spinal Implants
Authors: Lee Yoon Seok , Niinomi Mitsuo , Nakai Masaaki , Hieda Junko , Cho Ken
Published: May 2014

The wear mechanisms of a conventional titanium alloy, Ti–6Al–4V extra-low interstitial (Ti64), and a new titanium alloy, Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) were studied to investigate the wear properties of a Ti64/TNTZ combination for spinal fixation devices. Balls and discs made of Ti64 and TNTZ were prepared to be used as wear-test specimens. Frictional wear tests of Ti64 and TNTZ discs were carried out against Ti64 and TNTZ balls in air using a ball-on-disc frictional wear testing system. The wear mechanisms were investigated by analysis of worn surfaces and wear debris using scanning electron microscopy. Volume losses of the TNTZ discs were found to be larger than those of the Ti64 discs, regardless of mating ball. Furthermore, the morphologies of wear tracks and debris were found to be different between TNTZ and Ti64 discs. It is considered that the wear mechanism for a Ti64 disc is oxidative wear, whereas that for a TNTZ disc is delamination wear, regardless of mating ball material.
Study of Damage Mechanisms in Cold-Sprayed 316L-Matrix Composite Coatings Using Novel Impact-Sliding Testing
Authors: Maestracci R. , Fabrègue N. , Jeandin M. , Bouvard G. , Messaadi M. , Kapsa P. , Sova A. , Movtchan I. , Coulon J.F. , Malhaire J.M.
Published: May 2014

Cold spray is now well recognized as one of the most powerful and efficient coating process because it is cost-attractive and “green”. However, this process still shows limitations to achieve coatings for highly-demanding service conditions such as those required in certain automotive and/or aircraft applications. Beyond these limitations, cold spray is expected to compete with conventional P/M routes.The present work therefore focussed on the study of damage mechanisms in cold-sprayed AISI 316L and 316L-matrix–Cu composites coatings due to high-loading conditions. Different damage mechanisms could occur depending on the content of Cu particle addition, due to changes in the response of the microstructure to the loading. These mechanisms were studied using the newly-developed “impact-sliding” test. In this test, a steel ball impacts the coating surface at a given frequency, with a fixed angle. The influence of major testing parameters was investigated.Microstructures before and after testing were studied using optical microscopy, scanning electron microscopy (SEM), and microprobe analysis in addition to 3D optical profilometry of impacted areas. Damage mechanisms were seen to be of two types, i.e. plastic deformation and wear. These resulted in decohesion of splats, formation of wear debris and formation of a layer with a tribologically-transformed structure (TTS) at the contact surface.Results showed that cold spray could be claimed to be suitable for the achievement of high-performance coatings for industrial applications provided that the coating microstructure can be controlled. This could be done using a composite approach to the coating composition.
Morphology of Edge Cracks of Rolled Magnesium Alloy Sheet
Authors: Manabe Sho , Utsunomiya Hiroshi , Sakai Tetsuo , Matsumoto Ryo
Published: May 2014

Magnesium alloys show low deformability at low temperature because of hcp structure and inactiveness of basal slip. Manufacturing of thin sheet is difficult in industries. Some approaches, such as small-draft multi-pass rolling, intermediate annealing, isothermal rolling and high-speed rolling were proposed to overcome the deformability. However, small edge cracks are still formed on the sheet.
In this study, rolling speed of 1000m/min was employed to warm-roll AZ31B magnesium alloy in a single pass at different temperatures. The edge cracks formed after the rolling were classified into three main groups: minor, regular and zigzag edge cracks. ‘Crack contact length’ are introduced to explain the morphology of edge cracks. The results show that the critical reduction for crack initiation depends on the pre-heating temperature. The spacing between edge cracks increases linearly with the crack contact length regardless of roll diameter, speed and reduction. It is suggested that this approach is useful to understand the formation mechanism of edge cracks and to evaluate the rollability of magnesium alloys.
Magnetic Pulse Spot Welding: An Innovative Approach
Authors: Manogaran Arun Prasath , Manoharan Prabu , Priem Didier , Marya Surendar , Racineux Guillaume
Published: May 2014

The magnetic pulse welding is a rapid process (takes place within few micro seconds) that joins both homogeneous and heterogeneous materials in the solid state. The process involves applying variable high current on an inductor to generate Lorentz forces on to the conductive primary part (flyer). To realize the weld it is necessary to accelerate the flyer to impact on to the secondary stationary part (base material) at a very high velocity attained over the distance, called air gap, between the parts. It is typically possible to perform welding of tubes and sheets provided there is an optimized air gap between the parts to be welded. As part of our work we have developed an innovative approach (Magnetic Pulse Spot Welding-MPSW) that eliminates the delicate task of maintaining the aforementioned air gap between the plates. The proposed method opens better viable perspectives for heterogeneous assembly of automotive structures or connecting batteries in a quasi-cold state. The developed approach has been validated on the heterogeneous assembly Al/Fe by tensile tests (quasi-static and dynamic) that attested the quality of welds.
Finite Element Analysis of Material Flow and Characterization of Tube Dimensions of Indirectly Extruded Tailored Aluminum Tubes
Authors: Negendank Maik , Müller Sören , Reimers Walter
Published: May 2014

In this work the extrusion of tailored aluminum tubes is investigated. Therefore, a stepped mandrel was applied and moved in axial direction in order to vary the tube’s wall thickness. Since surface irregularities were observed on the tube’s surface in transition areas between the different wall thicknesses, the material flow was analyzed by FEM in order to clarify the origin of the surface defects. It was revealed that the inwardly directed material flow in combination with the lack of inward resistance when the mandrel step is moving in the region of the die bearing causes the geometric inhomogenities.
Effect of Zn/Mg on Age Hardening Behavior in 7000 System Al Alloys
Authors: Nishi Masatomo , Miura Naoya , Watanabe Katsumi , Ikeno Susumu , Yoshida Tomoo , Murakami Satoshi , Matsuda Kenji
Published: May 2014

7000 System Al has been known as one of the aluminum alloys with the good age hardening ability and the high strength among commercial aluminum alloys. [1]In this study, hardness measurement, tensile test, SEM observation and TEM observation have been performed in order to understand the effect of Zn/Mg ratio on age hardening behaviour in Al-Zn-Mg alloys .
It can be seen from hardness measurement that the alloy containing higher Zn and Mg contents became hard.
Tensile test was performed for the samples of peak aged condition. It can been seen that the alloy containing higher Zn and Mg increases the tensile strength of the alloy though decrease of the elongation were observed a typical intergranular fracture.
TEM observation was performed for peak aged samples. The size of precipitates became finer and the number density increased with increasing Zn and Mg contents.
Microstructural Control of Ductile Crack Propagation in TMCP HSLA Pipeline Steels
Authors: Carretero Olalla Victor , Sanchez Mouriño N. , Thibaux Philippe , Kestens Leo A.I. , Petrov Roumen
Published: May 2014

Control of ductile fracture propagation is one of the major concerns for pipeline industry, particularly with the increasing demand of new control rolled steel grades required to maintain integrity at high operational pressures. The objective of this research is to understand which microstructural features govern crack propagation, and to analyse the effect of two of them (average grain size, and volume fraction of pearlite). The main disadvantage during classical Charpy test was to discriminate the crack initiation and propagation energy during fracture of a notched sample. The initiation appears to be caused by the stress state in the neighbouring of Ti-containing precipitates or pearlite particles (no presence of M/A constituents or MnS inclusions was detected in the evaluated grades), propagation-arrest of the crack is assumed to play the main role concerning the control of fracture. Our approach to characterize the fracture resistance is to measure the energy absorbed during the crack propagation stage by means of load-displacement curves obtained via instrumented Charpy test. It was observed that the energy absorbed during crack propagation is not influenced by the average grain size but by the fraction and the morphological (banded-not banded) distribution of second pearlitic phase. This suggests that a different approach to characterize the heterogeneities in grain size clustering might be followed to correlate the energy measured during crack propagation and the morphological features of the steel.
High Temperature Oxidation Behavior of CM-247LC Nickel Base Superalloy
Authors: Chiou Mau Sheng , Yeh An Chou , Jian Sheng Rui , Kuo Chen Ming
Published: May 2014

The effects of Aluminum addition on the oxidation behavior of CM-247LC Nickel base superalloy were investigated under high temperature isothermal oxidation test at 1000°C in the dry air. In this study, we explored the difference and observed the micro-structure of oxides, gamma matrix as well as gamma prime precipitate, and further studied the impact of high temperature oxidation behavior and phase stability analysis. Results showed that by adding small amount of Al in CM-247LC superalloy, protective oxides could form more easily, and a more regular morphology of gamma prime in the base material microstructure could be retained, which in-directly reduced the rate of outward diffusion and prevented further oxidation.
Effect of Heat Treatment Condition on Texture in Ti-Mo-Al-Zr Shape Memory Alloy
Authors: Sasaki Tomoya , Hiramatsu Katsunori , Tahara Masaki , Hosoda Hideki , Miyazaki Shuichi , Inamura Tomonari
Published: May 2014

Effect of solution-treatment condition on texture of a Ti-Mo-Al-Zr shape memory alloy was investigated by X-ray pole figure measurement. Ti-Mo-Al-Zr alloy is a Ni-free and β-Ti based biomedical shape memory alloy. Unlike Ti-Nb system alloys, {110}β <001>β recrystallization texture was developed by the solution-treatment above β-transus as the reduction rate increases. However, this texture disappeared by the solution-treatment below β-transus and {531}β <134>β recrystallization texture was strongly developed. It was found that precipitation of hcp α phase has a significant effect on recrystallization texture in this alloy.