bluuebunny/crossref_metadata_2025 huggingface dataset:
MicroGap Area Detector for Stress and Texture Analysis
Authors: He Bob B.
Published: March 2011

Two-dimensional x-ray diffraction is an ideal method for examining the residual stress and texture. The most dramatic development in two-dimensional x-ray diffractometry involves three critical devices, including x-ray sources, x-ray optics and detectors. The recent development in brilliant x-rays sources and high efficiency x-ray optics provided high intensity x-ray beam with the desired size and divergence. Correspondingly, the detector used in such a high performance system requires the capability to collect large two-dimensional images with high counting rate and high resolution. This paper introduces the diffraction vector approach in two-dimensional x-ray diffraction for stress and texture analysis, and an innovative large area detector based on the MikroGap™ technology.
Influence of Residual Stresses on Fatigue Crack Propagation in Pearlitic Cold-Drawn Steel Wires
Authors: Brighenti Roberto , Carpinteri Andrea , Vantadori Sabrina
Published: March 2011

The aim of the present paper is to evaluate the effect of residual stresses, due to cold-drawing process, on the fatigue crack propagation in a pearlitic steel wire with a V-shaped circumferential notch. In order to analyse the effect of the notch severity on the residual stress distribution, three different values of the notch root radius are examined. The residual stress distributions in the reduced cross-section of such wires are numerically evaluated through FE analyses which simulate the material removing operation in the notched region. The stress-intensity factors (SIFs) related to tension loading and residual stresses are computed. Then, the crack propagation under cyclic tension combined with the residual stresses is analysed by taking into account the above SIF values and the actual stress ratio, which is different from that due to cyclic tension only.
Analysis of Residual Stress Effect on Fatigue Crack Propagation in Bonded Aeronautical Stiffened Panels
Authors: Meneghin Ivan , Ivetic Goran , Troiani Enrico
Published: March 2011

The application of adhesively bonded straps made of high-static strength materials on aeronautical stiffened panels to retard the fatigue skin crack growth is currently a topical research subject. The detrimental effect of the residual stress fields induced as a consequence of the dissimilar coefficients of thermal expansion of the skin and strap materials on the fatigue skin crack propagation was investigated. The residual stresses induced in a stiffened panel representative of a pressurized fuselage shell with titanium doublers in the middle of the stringer bays is numerically quantified for two likely operational temperatures. Their effect on the fatigue crack propagation is analyzed by means of a linear elastic fracture mechanics approach. The results show that adhesively bonded straps on the cracked surface can significantly retard the fatigue crack propagation but, in order to achieve reliable and conservative predictions on their performances, the effect of the residual stress fields they introduce must be taken into account.
Hydrogen Accelerated Classical Rolling Contact Fatigue and Evaluation of the Residual Stress Response
Authors: Gegner Jürgen , Nierlich Wolfgang
Published: March 2011

The accelerating effect of absorbed hydrogen on subsurface rolling contact fatigue is studied by bearing rig testing under HF electric current passage. The additional chemical loading enhances dislocation mobility and microplasticity. Structural changes occur in a premature stage, as shown by comparative XRD residual stress analysis. Dark etching regions appear to be a precursor for phase transformation in regular white etching bands. Fatigue crack initiation is demonstrated.
X-Ray Diffraction Determination of Macro and Micro Stresses in SOFC Electrolyte and Evolution with Redox Cycling of the Anode
Authors: Villanova Julie , Sicardy Olivier , Fortunier Roland , Micha Jean Sebastien , Bleuet Pierre
Published: March 2011

Solid Oxide Fuel Cell (SOFC) is a high-performance electrochemical device for energy conversion. Usually, the electrolyte is made of dense YSZ (Yttria Stabilized Zirconia) and the anode is a porous YSZ-Ni composite. The electrolyte is submitted to high stresses mainly due to the thermal expansion coefficient mismatch between components and the volume change associated with the redox cycling of Ni. Because the mechanical integrity of the cell is a major issue during its life time, it is proposed in this study to determine both micro and macro stresses in the electrolyte. Macro stresses in the 10 µm-thick electrolyte were measured using the sin²(Ψ) method after different treatments of the cell : (i) manufacturing, (ii) thermal cycle, (iii) reduction and (iv) re-oxidation of the anode layer. After manufacturing, the electrolyte is under strong biaxial compressive stresses (-690 MPa). These stresses decrease after reduction of the anode. They finally reach tensile stresses and induce the cracking of the electrolyte for full re-oxidation. Micro stresses determinations were performed using the micro-diffraction setup of the BM32 beam line at ESRF (European Synchrotron Radiation Facility). Complete strain-stress tensor and crystallographic orientation determinations have been achieved within 5 µm grains. The accuracy of the method has been improved and is now 2.4 10-4 for strain values. On an average, local measurements are found to be consistent with global ones. Both strain and stress heterogeneities between grains with various orientations have been evidenced.
Integration of Residual Stresses in the Design of Mechanical Parts
Authors: Elgueder Jawhar , Roucoules Lionel , Rouhaud Emmanuelle , Cochennec Florent
Published: March 2011

This paper presents an original approach in mechanical design to integrate the manufacturing constraints in the final CAD model. A specific user-interface is proposed to integrate manufacturing constraints (for example tolerances) and manufacturing consequences (for example roughness or hardening) into the model. One of the important consequences of manufacturing processes is the generation of residual stresses into the part. An appropriate tool has been developed and used as a design tool to manage the global evolution of residual stresses in the mechanical part and to obtain the deformed geometry resulting from the applied manufacturing plan. These results could eventually be used in fatigue simulation. To support the model, a database is used for the integration of residual stresses from stored experimental results, analytical or numerical calculations. An example of a metal sheet, laminated and deformed by shot peening is given, the deformed geometry is rebuilt and compared to the experimental results.
Analytical and Experimental Approach of Residual Stress on Deep-Rolled Crankshafts and Auto-Fretted Diesel Injection Rails. Effect on Fatigue Resistances in Service
Authors: Michaud H. , Sprauel Jean Michel
Published: March 2011

The fatigue resistance of car components such as crankshafts or diesel injection rails is mainly related to fatigue at geometrical singularities. Its understanding requires the simulations of the different steps of the industrial process resulting in residual stresses generation and their evolutions in service. First concerning crankshaft fatigue damage, a complete analytical model of residual stresses generation and shakedown in fatigue is presented. Then a fatigue criterion is established and validated for this application. Finally, for the high pressure diesel injection rail, this approach can be generalized to the holes intersection singularities.
Effects of Brushing and Shot-Peening Residual Stresses on the Fatigue Resistance of Machined Metal Surfaces: Experimental and Predicting Approaches
Authors: Sidhom Naziha , Sidhom Habib , Braham Chedly , Lédion Jean
Published: March 2011

Mechanical brushing of machined AA5083H11 surface, performed in optimized conditions of brush wire hammering, generates distributions of compressive residual stresses. These distributions are controlled by the process parameters such as the pressure of the brush wires on the surface, the speed of rotation or the number of passes. X-ray diffraction (XRD) measurements relative to different surface preparations show that the stresses due to brushing are less deep and that the maximal values in compression are the same as the ones from shallow shot-peening treatment (without defects). Moreover, the bushing provides high quality surface at a microscopic scale (low roughness) and integrity state of the treated surfaces, better for cyclic stability of compressive stresses. The stabilized state of residual stresses resulting from brushing and shot-peening is determined by finite element analysis. These analyses are experimentally validated by XRD using the psi-tilt method on tested fatigue specimens. Fatigue results show that the good surface topography generated by the wire brushing process compensates the reduction of the amplitude and the depth of the compressive residual stress profiles compared to shot-peening so that it could provide an equivalent fatigue improvement rate (20 to 30% of σD2.106cycles) of the AA5083H11.
Experimental and Numerical Analysis of the Distribution of Residual Stresses Induced by Laser Shock Peening in a 2050-T8 Aluminium Alloy
Authors: Hfaiedh Neila , Peyre P. , Popa I. , Vignal Vincent , Seiler Wilfrid , Ji V.
Published: March 2011

Laser shock peening (LSP) is an innovative surface treatment technique successfully applied to improving fatigue performance of metallic material. The specific characteristic of (LSP) is the generation of a low work-hardening and a deep compressive residual stresses mechanically produced by a laser-induced shock wave propagating in the material. The aim of this study is to analyse the residual stress distribution induced by laser peening in 2050-T8 aluminium alloy experimentally by the X-ray diffraction technique (method sin2Y) and numerically, by a finite element numerical modelling. A specific focus was put on the residual stress distribution along the surface of the impacted material.
Calculation of X-Ray Stress Factors Using Vector Parameterization and Irreducible Representations for SO(3) Group
Authors: Benediktovich Andrey , Feranchuk Ilya , Ulyanenkov Alex
Published: March 2011

In the presence of texture, the concept of X-ray elastic constants as well as Sin2ψ law is inapplicable and the X-ray stress factors (XSF) connecting average strain and stress have to be used [1-2]. The SO(3) vector parameterization with smart composition law [3-4] proved to be a powerful tool for handling transformations between reference systems used in XSF calculation. Decomposition of the 4-th rank elastic constant tensor on the SO(3) irreducible representations (IR) allows one to highlight the symmetry properties and to separate isotropic and anisotropic parts. Joint use of the vector parameterization and IR decomposition enables to obtain transparent analytical expressions for XSF in case of textures described by preferred spherical/fiber components.
Unconventional Performance of a Highly Luminous Strain/Stress Scanner for High Resolution Studies
Authors: Seong Baek Seok , Em Vyacheslav T. , Mikula Pavol , Šaroun Jan , Kang Mi Hyun
Published: March 2011

In this paper properties of the dedicated neutron strain/stress diffractometer installed at the beam port ST-1 of HANARO reactor in KAERI which has been optimized at a small monochromator take-off angle, are described. Thanks to the employment of the horizontally focusing bent perfect crystal monochromator and the optimization procedure good resolution can be achieved and namely, the luminosity of the instrument can be considerably increased which permits us to enlarge the range of the material depth for residual strain/stress mapping. Moreover, new alternative of the diffractometer permits also to investigate some kinetic processes in polycrystalline materials running within few seconds.
Residual Stress, Texture, and Phase Investigation of Autogenous Edge Welds Using High Energy Synchrotron Radiation
Authors: Martins René V. , Francis John A.
Published: March 2011

Two autogenously edge welded beams made from SA508 ferritic steel were investigated with the purpose of validating residual stress modelling tools which are relevant for integrity assessment of structural power plant components. The two specimens were welded with two different torch travel speeds. The residual strain and phase distributions were non-destructively determined by high-energy synchrotron X-ray diffraction. Good agreement between numerical and experimental data was found for the specimen welded at fast speed. Furthermore, the texture changes in the specimen welded at slow speed were analysed by the same experimental technique.
Strain Evolution during Mechanical Loading of the Magnesium Base Alloy LAE442 Studied by means of High Energy Synchrotron Diffraction
Authors: Gibmeier Jens , Maier Petra , Fleck Claudia
Published: March 2011

The highly alloyed wrought Mg-base alloy LAE442 is characterized by a relatively high creep resistance due to secondary phases which are thermally stable. In general the elasto-plastic deformation behavior of Mg-base alloys is due to dislocation slip and twinning depending on the local crystallographic texture with respect to the direction of load application. LAE442 exhibits a rather weak influence of the crystallographic texture after extrusion on the mechanical properties resulting in nearly identical compressive and tensile yield strength values. The relatively high strength of LAE442 is based on a high number of small Al-RE (RE = rare earth) -precipitates. In the present investigation, we studied the load distribution between the different phases of LAE442 as well as the evolution of the lattice strains under tensile and compressive loading in order to gain valuable insight into the deformation behavior of the alloy. In-situ deformation experiments coupled with energy dispersive diffraction by means of high energy synchrotron radiation allow this kind of investigation. High energy synchrotron X-ray stress analyses were carried out on cylindrical specimens that were uniaxially loaded. The diffraction experiments were carried out at the EDDI-beamline at BESSY II, Berlin, using a white beam up to energies of 150 keV. Diffraction data were analyzed according to the well known sin²y - method. As a result of the studies the X-ray elastic constant (XEC) ½ s2{hkl}was evaluated for the individual phases.
Advances on NDT Methods and Technologies for Early Stage Diagnosis of Materials
Authors: Berti Giovanni , De Marco Francesco , Aldrighetti S.
Published: March 2011

The early stage diagnoses of material lattices is becoming a crucial requirement where investigation methods and technologies are faced with both aging of components and materials. The mixing effects of wear, fatigue, temperature variation and environment conditions translate into variations of the atomic flux rate and internal rearrangement of grain size and boundaries of lattices. The related lattice measurements (e.g. the d-.spacing is one important among others) become the only one usable for early stage diagnoses of the lattice structural integrity. When such a diagnoses are the base to identify the qualification of material for the use or the re-qualification for the maintenance in the use, new technologies are required, with methods and appropriate concepts shall be used. The authors bid here to describe shortly the historical evolution of methods and techniques since the 70’s, along with the basic tests performed during the early 90’s of the past century. The technological follow up from those tests is reported along with some results which indicate the significant step up of the most recent technology toward the early stage diagnosis of material via on site x-ray diffraction. Further foreseeable development and advances are also mentioned.
Generation of Residual Stresses and Improvement of Surface Integrity Characteristics by Laser Shock Processing
Authors: Trdan Uros , Grum Janez , Hill Michael R.
Published: March 2011

The influence of different parameters of laser shock processing applied to a precipitation-hardened aluminium alloy 6082-T651, on residual stress, surface tophraphy and microhardness was investigated. Processing was performed with an innovative Nd:YLF laser with the power densities of 2 and 4 GW/cm2, with a uniform pulse duration of 18 ns. Laser shock processing experiments were performed with the closed ablation method to ensure a higher shock-wave pressure. In the first phase, the study was focused on an evaluation of surface topography, with the record of the surface roughness profile and with the surface evaluation at a scanning electron microscope JEOL JXA-8600M. Then followed measurement of microhardness HV0.2in the cross section region. In the second phase comparison of residual stresses which were measured using the X-ray diffraction, was performed. Laser shock processing turned out to be a very efficient technique to improve surface properties. On the basis of the micro plastic deformation induced by shock waves, an increased dislocation density in the specimen surface was obtained. The gradient of dislocation piling through the specimen depth improved the variation of microhardness and residual stresses, which, in turn, improves fatigue strength of the material under dynamic loading.
The Effect of Pre-Weld Rolling on Distortion and Residual Stress in Fusion Welded Steel Plate
Authors: Coules Harry E. , Cozzolino Luis D. , Colegrove Paul A. , Wen Shu Wen
Published: March 2011

Local rolling and other mechanical tensioning techniques can be highly effective at reducing residual stress and distortion in thin plate welds prone to buckling. However, the issues of high capital cost and low scalability currently prevent wider adoption of such processes. Pre-weld rolling aims to address these issues and can be applied easily to each component prior to fabrication. The results of an initial trial are presented, and indicate that post-weld distortion can be reduced by an average of 38% when correct rolling parameters are used. Finally, the mechanism by which pre-rolling acts to modify the state of residual stress around a weld line is discussed.
Residual Stresses Induced by Laser Peening of Thin Aluminium Plates
Authors: Burak Toparli M. , Fitzpatrick Michael E.
Published: March 2011

Laser shock peening offers potential advantages over conventional peen technologies in terms of the depth of the residual stresses that can be induced, and improvements in surface roughness. In this study the application of laser peening to thin aluminium plates such as are used in aerospace applications is investigated. Peening of thin plates presents challenges in balancing the peen intensity to prevent overpeening that will actually lower the stress field. Strain profiles for different laser peening parameters were obtained using synchrotron X-ray diffraction at the ESRF, France. Results are presented and discussed of the residual strain profiles in terms of the laser power density and the number of peen passes. When the power density and number of passes are increased the compressive strain magnitudes are also increased, as has been observed in previous studies. However, the strain components longitudinal and transverse to the peen line are not identical to each other, with the transverse component being much less compressive.
Experimental Study of the Micromechanical Behaviour of Duplex Stainless Steel SAF 2507 and the Influence of Nitrogen Content
Authors: Peng Ru Lin , Chai Guo Cai , Stein Tobias , Manns Thorsten , Johansson Sten
Published: March 2011

The deformation behaviour of four super duplex stainless steels of the grade SAF 2507 (UNS S32750) were studied by X-ray diffraction experiment with in-situ uniaxial tensile load. The steels had different nitrogen contents, between 0.2 and 0.33%, and/or different volume fractions of the ferrite, between 37% and 49%, in balance with austenite. The development of phase-specific stresses under external loading up to over 10% tensile strain was followed. The X-ray diffraction measurements revealed that load partitioning between the phases changed with increasing applied load, as the ferrite and austenite exhibited different deformation hardening behaviours. At the onset of macroscopic yielding and low plastic strains, a load transfer from γ to α occurred due to higher yield strength and strain hardening rate of the ferrite but vice versa at larger plastic strains when the austenite hardened more rapidly than the ferrite. It was also concluded that both the yield and tensile strengthen of the steels increased with increasing nitrogen content due to increased strengthen of the austenite by additional solid solution hardening, whereas a higher volume fraction of austenite contributed to higher tensile strength.
Validation of Residual Stresses of Finite Element Simulation of Multi Pass Butt-Welded Plates Using the Contour Method
Authors: Rodríguez Eduardo , Martín Cristina , Cortizo José Luis , Guirao Julio , Sierra José Manuel
Published: March 2011

In this paper a comparison between the results obtained using multi pass welding finite element (FE) simulation and the contour method was made to evaluate the accuracy in residual stresses simulated for plates with different thicknesses. The contour method has been used to measure the residual stresses in multi pass butt-welded plates. Two 316 austenitic stainless steel multi pass Metal Inert Gas (MIG) butt-welded plates of 10 mm thickness were cut using wire Electric Discharge Machining (EDM). The measurements of the cross-section were made with a coordinate measuring machine (CMM) and the points obtained were used to calculate the residual stresses by mean of static analysis of finite elements. A multi pass welding FE simulation of the two plates was made to obtain the residual stresses after time cooling. The simulated results are generally in good agreement with the experimental measurements. Other plates of 25 mm thickness and the same material were multi pass MIG butt-welded to evaluate the behavior with different thicknesses. In this case the number of passes was 11. The same method was applied to obtain the residual stresses. A comparison between different thicknesses was made. The residual stresses validation will allow the finite element simulation to be used for the later simulation of residual stresses relaxation.
The Matrix Method for Data Evaluation and its Advantages in Comparison to the Sin2ψ and Similar Methods
Authors: Ortner Balder
Published: March 2011

This article gives an overview of different methods for data treatment in x-ray stress measurement, and how these methods should be replaced with the matrix method, which in general is more versatile, more accurate and, in most cases, also easier to handle. It also shows how much the accuracy could be improved by replacing the traditional methods with the matrix method.
Developments in the Treatment of Residual Stresses in Welded Components
Authors: Bate Steve K. , Symington Ian , Sharples John , Charles Richard , Toft Adam , James Peter , Hurrell Paul , Jackson Mark
Published: March 2011

A long-term UK research programme on environmentally assisted cracking (EAC), residual stresses [1, 2] and fracture mechanics [3, 4] was launched in 2004. It involves Rolls-Royce plc and Serco Technical Services, supported by UK industry and academia. The residual stress programme is aimed at progressing the understanding of residual stresses and on the basis of this understanding manage how residual stresses affect the structural integrity of plant components. Improved guidance being developed for the treatment of residual stresses in fracture assessments includes the use of stress intensity factor solutions for displacement controlled loading as opposed to the more commonly used load controlled solutions. Potential reductions in crack driving force are also being investigated in relation to (i) utilizing a residual stress field that has “shaken-down” due to operational loads, (ii) introducing a crack progressively as opposed to instantaneously, and (iii) allowing for the fact that a crack may have been initiated during the life of a component as opposed to being present from the start-of-life. This paper describes some of these latest developments in relation to residual stress effects
Welding Residual Stresses Depending on Solid-State Transformation Behaviour Studied by Numerical and Experimental Methods
Authors: Heinze Christoph , Kromm Arne , Schwenk Christopher , Kannengiesser Thomas , Rethmeier Michael
Published: March 2011

The development of high-strength structural steels with yield strengths up to 1000 MPa results in the requirement of suitable filler materials for welding. Recently designed low transformation temperature (LTT) alloys offer appropriate strength. The martensitic phase transformation during welding induces compressive residual stress in the weld zone. Therefore, the mechanical properties of welded joints can be improved. The present paper illustrates numerical simulation of the residual stresses in LTT-welds taking into account the effect of varying Ms/Mf-temperatures, and therefore different retained austenite contents, on the residual stresses. Residual stress distributions measured by synchrotron diffraction are taken as evaluation basis. A numerical model for the simulation of transformation affected welds is established and can be used for identification of appropriate Ms-temperatures considering the content of retained austenite.
Analysis of Ductile Damage – Comparison between Micromechanical Models and Neutron Diffraction Experiments
Authors: Panicaud Benoit , Cauvin Ludovic , le Joncour Lea , Baczmanski Andrzej , Saanouni Khemais , François Manuel
Published: March 2011

Ductile damage is a consequence of large strains more or less localized. Taking into account damage in constitutive behaviour of metallic materials is necessary to model various engineering problems involved in forming processes (stamping, punching, shearing...). It would lead to accurate predictions introducing microstructural features of materials [1-2]. In the present study, two crystalline plasticity models including damage effects in the framework of scale transition methods are investigated. These models are developed and based on different approaches with direct application to duplex stainless steels. The first approach is a variant of the Berveiller-Zaoui model in which the effect of ductile damage has been introduced. The second one is a generalized Cailletaud model taking into account the ductile damage [3-6]. Because of the microstructural complexity of the chosen materials, some particular developments of the micromechanical approaches are considered. Moreover, continuous damage mechanics is used at grain scale including its effect (or coupling) on plastic or elastic-plastic flow with more or less complex hardenings. The modelling is justified on some previous experimental results in metallic duplex materials [7-8]. The developed models allow then deducing the macroscopic behaviour of the aggregate with damage effects from the grains behaviour.
Microstructure and Mechanical Properties of CP-Ti Processed by 2 ECAP Passes Using a 90° Die at Room Temperature
Authors: Yang Xi Rong , Zhao Xi Cheng , Liu Xiao Yan
Published: March 2011

Equal channel angular pressing (ECAP) deformation for commercial pure titanium (CP-Ti) was successfully conducted using a conventional die with an angle of 90° between the channels at room temperature via route B, in which the billet was rotated 90° along its longitudinal axis between adjacent passes. Each billet was processed for two passes using a ram speed of 26mms-1. The microstructures and mechanical properties of these CP-Ti billets with an initial grain size of ~23μm processed by ECAP were investigated. Experiment results show thin parallel shear bands with a width of 0.3~0.4μm are generated after one ECAP pass, which are composed of large number of dislocation cell blocks. After the two ECAP passes, some various directional bands are generated and the equiaxed and smaller-than-average CBs in local areas begin to appear. In addition, the ultimate strength and microhardness are significantly enhanced to ~725MPa and ~2283MPa, respectively. Meanwhile good elongation of 18.0% to failure is still remained.
Mechanical Properties of Plain Carbon Steels with Ultrafine (α+θ) Microstructures
Authors: Zhu Hai Yan , Li Long Fei , Yang Wang Yue , Sun Zu Qing
Published: March 2011

Mechanical properties of a medium-carbon steel with the ultrafine (α+θ) microstructures obtained by hot deformation of undercooled austenite and annealing were investigated by tensile tests, in comparison with that of a eutectoid steel. The results indicated that in the case of hot deformation of undercooled austenite to strain of 1.61 at 650°C at 0.01s-1 and annealing at 650°C for 30min, the ultrafine (α+θ) microstructures consisting of ultrafine ferrite grains and dispersed cementite particles were similar in the medium-carbon steel and the eutectoid steel, but the mechanical properties of the eutectoid steel were better that maybe be attributed to the relatively coarser size and the higher amount of cementite particles. With the increase of temperature for hot deformation of undercooled austenite to 700°C, the ultrafine (α+θ) microstructure of the medium-carbon steel changed obviously with the presence of some spheroidized pearlite colonies, and demonstrated the best balance of strength and elongation, the yield strength of about 545MPa, the tensile strength of about 635MPa, and the total elongation of about 35%.
Effect of Load Direction on Tensile Yield Properties in Mg-3Al-Zn Alloy
Authors: Liu Ran , Yin De Liang , Wang Jing Tao
Published: March 2011

Deformation anisotropy of samples from rolled sheet and extruded rod of AZ31 alloy was investigated in the present work. A strong basal plane texture is detected formed during rolling and extrusion, and both rolled and extruded samples exhibit similar mechanical behavior: tensile yield strength is the highest in the specimens parallel to the longitudinal direction, and decrease continuously as the specimen orientation departs from the longitudinal direction. Using texture analysis and optical microscopy it has been found that, the obvious anisotropy can be explained by texture and orientation factor during tension and compression. Basal slip and twinning are restricted when tensile load is applied in the rolling and extrusion direction, which results in high tensile yield strength along the two directions.
Compression Superplasticity of Ultrahigh Carbon Steel in Electric Field
Authors: Zhang Ke Ke , Yue Yun , Zhang Z.L. , Ma Ning , Liu S. , Shi Hong Xin , Yu Hua , Wang Yao Li
Published: March 2011

Taking 1.4%C and 1.6%C ultrahigh carbon steels (UHCSs) with ultra-fine structures developed through thermo-mechanical processing as research objects, the influences of superplastic deformation conditions and electric field on compression superplasticity were conducted without electric field and with electric field. The experimental results indicate that 1.4%C and 1.6%C UHCSs have respectively superplasticity or electro-superplasticity under the conditions of deformation temperature of 800°C, the initial strain rate of 0.75-3.75×10-4 s-1 and deformation temperature of 780 °C, the initial strain rate of 0.5-5.0×10-4 s-1 and the suitable external electric field. Its strain rate sensitivity are respectively 0.32 and 0.46.When the electric field intensity of 3 kV/cm in the manner of the specimen connected to positive terminal, the steady flow stress of 1.6%C UHCS decreases more than 10.5% as compared with electric field intensity of 0 kV/cm.
Studies of Annealing Process in Severely Cold Drawn Pearlitic Steel Wires
Authors: Liu Shi Feng , Liu Ga , Wang Bo Jian , Ren C.H. , Shi Xiao Li
Published: March 2011

The effects of spheroidizing annealing process on SWRH72B heavily cold drawn pearlite steel wires were studied and the mechanisms of low-temperature spheroidizing annealing were discussed. The results show that, with increasing drawing strain, the spheroidizing annealing temperature and time decreased and uniformity of the spheroidizing increased; the mechanism of low-temperature spheroidizing annealing was different from the traditional one of heavily cold drawn pearlite steel wires. When the true strains were between 2.85 and 5.1, the spheroidizing process of carbide could be divided into two stages: partial dissolution of lamellar carbide, and the precipitation and accumulation of compulsory dissolved cementite. When the true strains were larger than 5.1, the spheroidizing process of carbide was only characterized by precipitation and accumulation of compulsory dissolved cementite.
Microstructure and Properties of Ultrafine-Grained Steel Produced by Warm Compression of Martensite
Authors: Zhao Xin , Yang Xiao Ling , Jing Tian Fu
Published: March 2011

Specimens of medium carbon steel were quenched and warm-compressed on a Gleeble 3500 Machine. The microstructure of the specimens was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that the starting microstructure is lath martensite with a small amount of flake martensite. After 50% compression at 550-650°C, ultrafine grains can be observed in the specimens. The microstructure of the specimens compressed at 600°C is equiaxed ultrafine ferrite grains + nano-carbides and a good combination of strength and ductility is obtained. The tensile strength and total elongation are 861MPa and 19.1%, respectively. The hardness is 233.81Hv.
Erosion Wear Property of Surface Diffusion Alloyed Coatings on Magnesium Alloy
Authors: Ma You Ping , Li Xiu Lan , Yang Lei , He Xi Peng
Published: March 2011

Erosion wear tests under different erosion slurry mediums were carried out to investigate erosion properties of the treated samples of ZM5 magnesium alloy by surface diffusion alloying processing (SDAP).The result indicated that the micro-hardness (HV172) near the surface of alloyed specimen was about twice more than that of its substrate(HV82) after treated at 390°C for 8h.The erosion wear resistance β (0.68×104 mm2/g) of the treated specimen was better than that of untreated specimen (0.48×104mm2/g) under the conditions of erosion slurry of oil and quartz. The difference of erosion wear resistance between them was primary due to cutting wear mechanism. While erosion mediums was changed to the slurry of water and quartz, the wear resistance β of the treated specimen increase up to 0.24×104 (mm2/g), and that of the untreated specimen was only 0.09×104 (mm2/g),the difference between them resulted from corrosion wear mechanism predominating, which worsen the erosion wear resistance β.
Electroactive Organic-Inorganic Layered Perovskite Hybrids: Steric Interaction between Aminopyridine and Trivalent Ferricyanide and Use for Electrochemical Sensing Device
Authors: Wu Jing , Liu Han Xing , Lin Zhi Dong , Cao Ming He , Guo Li Lin , Hao Hua , Yu Zhi Yong
Published: March 2011

Steady organic-inorganic perovskite hybrids with (H22-Ap)3/2Fe(CN)6, (H23-Ap)3/2Fe(CN)6 and (H24-AP)3/2Fe(CN)6 (2-AP = 2-aminopyridine, 3-AP = 3- aminopyridine, 4-AP = 4- aminopyridine) were formed from aqueous solution. Each structure was an unusual layered organic-inorganic structural type. A device was designed to construct electrochemical sensing devices using above organic-inorganic perovskite hybrids. The sequence of redox activity is (H24-Ap)3/2Fe(CN)6 > (H22-Ap)3/2Fe(CN)6 > (H23-AP)3/2Fe(CN)6 and that of electrocatalytical activity is (H22-Ap)3/2Fe(CN)6 > (H23-Ap)3/2Fe(CN)6 > (H24-AP)3/2Fe(CN)6. The variation coefficients (RSD) of successive and interval assays are less than 2.0%. Three electrochemical sensing devices display a remarkable electrochemical sensitivity and stability.
Solidification Structure Characteristics and Mechanical Properties of (Ag-Cu28)-25Sn Alloy Ribbons Prepared by Melt Spinning Method
Authors: Li Liang Feng , Qiu Tai , Yang Jian , Feng Yong Bao
Published: March 2011

To obtain novel intermediate temperature alloy solders with melting temperature of 400~600°C, (Ag-Cu28)-25Sn alloy ribbons were prepared by high frequency induction melting and melt spinning at different quenching linear speed. The effect of the development of solidification structure on melting properties and microhardness of the ribbons were investigated. The XRD results show that the as-prepared alloy ribbons have the same phase composition as the master alloy, which consists of Ag4Sn and Cu3Sn. With the quenching linear speed increasing, the solidification structures are refined and change from dendritic crystals to uniform granular crystals. As the quenching linear speed increases up to 32.25m/s, the grain size of the alloy ribbon has a distribution ranging from submicron to about 2μm. The DSC results indicate that the melting properties of alloy ribbons strongly depend on the solidification structure, and the melting temperature of alloy ribbons decreases with the quenching linear speed increasing. The lowest liquidus points of the alloy ribbon prepared at linear speed of 32.25m/s are located at 473.6°C and 524.7°C, respectively. The refined solidification structure notably increases the microhardness of the alloy ribbons, and the largest hardness value of 396HV is obtained for the alloy ribbon prepared at linear speed of 32.25m/s, which increases 27.0% compared with the master alloy.
Deformation Processing and Mechanical Properties of Cu-10Cr-0.4Zr In Situ Composite Microwires
Authors: Deng Jian Qi , Zhang Xiu Qing , Shang Shu Zhen , Zhao Zu Xin , Ye Yi Fu
Published: March 2011

The Cu-10Cr-0.4Zr in situ composite microwires were prepared by cast and cold drawing procedure. Deformation processing and mechanical properties of Cu-10Cr-0.4Zr composites were investigated. The results showed that the additional 0.4wt. %Zr in the Cu-10Cr in situ composite microwires gave birth to smaller as-cast Cr phases, which led to refined filaments in the matrix at higher drawing strains. As the drawing strains increased, the Cr filaments were constrained to fold or twist (even overlapped together) on longitudinal sections, and the Cr filaments become homogeneity and refinement at the longitudinal sections at the same time. At η=6.2, the thickness of Cr filaments reached 250-300nm, and the ultimate strength of Cu-10Cr-0.4Zr composites reached 1089 MPa. And the predicted strength using Hall-Petch equation was 1037 MPa, which was in reasonably good agreement with the observed strength (1089 MPa).
Microstructure and Mechanical Properties of Austempered Ultrahigh Carbon Steel 1.4%C
Authors: Zhang Zhan Ling , Zhang Ke Ke , Yue Yun , Ma Ning , Xu Zhi Wei
Published: March 2011

An ultrahigh carbon steel alloy containing 1.4 wt pct carbon (UHCS-1.4C) was studied. The steel was processed into ultrafine grain and fully spheroidized microstructure through a controlled rolling and controlled-cooling divorced eutectoid transformation, and was then given austempering treatment to form bainite. The mechanical properties of the heat-treated steel were evaluated by tension tests at room temperature. After austenitized at 850 °C and then austempered at 300 - 350 °C, the microstructure was ultrafine upper bainite, retained austenite, and unsolvable cementite. It was shown that the ultimate tensile strengths of UHCS-1.4C ranged from 1420 to 1830 MPa, elongations to failure from 6 to 14%; the ultimate tensile strength increases with decreasing austempering temperature, while the tensile ductility decreases. The fracture surface of bainitic UHCS-1.4C consists mainly of dimples and voids, which reveal a ductile fracture. The present results indicate that ultrahigh carbon steel can be easily processed to achieve bainitic microstructures and unique properties.
Statins: Cardiovascular Risk Reduction in Percutaneous Coronary Intervention—Basic and Clinical Evidence of Hyperacute Use of Statins
Authors: Morales-Villegas Enrique C. , Di Sciascio Germano , Briguori Carlo
Published: March 2011

Reduction of LDL-cholesterol concentration in serum, blocking the isoprenylation of GTPases and the activation of myocyte-protective enzyme systems are three mechanisms that currently explain the lipid and non-lipid effects of statins. However, the decrease of LDL-cholesterol, the reduction of inflammation biomarkers and even the atheroregresion, as surrogate effects to the mechanisms of action of statins would be irrelevant if not accompanied by a significant decrease in the incidence of cardiovascular events. Statins like no other pharmacological group have proven to reduce the incidence of cardiovascular events and prolong life in any clinical scenario. This article review the basic and clinical evidence that support a new indication for HMG-CoA reductase inhibitors “pharmacological myocardial preconditioning before anticipated ischemia” or hyperacute use of statins in subjects with any coronary syndrome eligible for elective, semi-urgent or primary percutaneous coronary intervention: ARMYDA-Original, NAPLES I-II, ARMYDA-ACS, ARMYDA-RECAPTURE, Non-STEMI-Korean, Korean-STEMI trials.
Ambulatory Blood Pressure Monitoring in Diabetes and Obesity—A Review
Authors: Eguchi Kazuo
Published: March 2011

Diabetes mellitus and obesity are both related to the risk of cardiovascular disease and sudden death. In hypertensive guidelines, diabetes and obesity, especially abdominal obesity, are regarded as high-risk factors. Ambulatory blood pressure monitoring (ABPM) is an established method for the management of hypertension. However, ABPM is not a standard tool for the management of hypertension in diabetes and obesity. In this paper, recent data on the use of ABPM in diabetes and obesity will be discussed. In patients with diabetes, the ambulatory BP level has been shown to be better than clinic BP in predicting cardiovascular events. A riser pattern has been associated with increased risk of cardiovascular disease. White-coat hypertension and masked hypertension in diabetics constitute a moderate risk. A nondipping pattern is very common in obese hypertensive patients. In this paper, we will summarize the findings on the use of ABPM in patients with diabetes and obesity.
Preventing Transmission of Infectious Agents in the Pediatric in-Patients Hematology-Oncology Setting: What Is the Role for Nonpharmacological Prophylaxis?
Authors: Caselli Désirée , Cesaro Simone , Livadiotti Susanna , Ziino Ottavio , Paolicchi Olivia , Zanazzo Giulio , Milano Giuseppe , Licciardello Maria , Barone Angelica , Cellini Monica , Raffaella De Santis , Giacchino Mareva , Rossi Mario Renato , Aricò Maurizio , Castagnola Elio
Published: March 2011

The most intensive chemotherapy regimens were used in the past for leukemia patients who were the main focus of trials on infections; today there are increasing numbers of children with solid cancer and considerable risk of infection who do receive intensive stand ard-dose chemotherapy. Despite a continuous will to protect the immune-compromised child from infections, evidence-based indications for intervention by non-pharmacological tools is still lacking in the pediatric hematology-oncology literature. Guidelines on standard precautions as well as precautions to avoid transmission of specific infectious agents are available. As a result of a consensus discussion, the Italian Association for Pediatric Hematology-Oncology (AIEOP) Cooperative Group centers agree that for children treated with chemotherapy both of these approaches should be implemented and vigorously enforced, while additional policies, including strict environmental isolation, should be restricted to patients with selected clinical conditions or complications. We present here a study by the working group on infectious diseases of AIEOP.
Five Methods of Breast Volume Measurement: A Comparative Study of Measurements of Specimen Volume in 30 Mastectomy Cases
Authors: Kayar Ragip , Civelek Serdar , Cobanoglu Murat , Gungor Osman , Catal Hidayet , Emiroglu Mustafa
Published: March 2011

Background

To compare breast volume measurement techniques in terms of accuracy, convenience, and cost.

Methods

Breast volumes of 30 patients who were scheduled to undergo total mastectomy surgery were measured preoperatively by using five different methods (mammography, anatomic [anthropometric], thermoplastic casting, the Archimedes procedure, and the Grossman-Roudner device). Specimen volume after total mastectomy was measured in each patient with the water displacement method (Archimedes). The results were compared statistically with the values obtained by the five different methods.

Results

The mean mastectomy specimen volume was 623.5 (range 150–1490) mL. The breast volume values were established to be 615.7 mL (r = 0.997) with the mammographic method, 645.4 mL (r = 0.975) with the anthropometric method, 565.8 mL (r = 0.934) with the Grossman-Roudner device, 583.2 mL (r = 0.989) with the Archimedes procedure, and 544.7 mL (r = 0.94) with the casting technique. Examination of r values revealed that the most accurate method was mammography for all volume ranges, followed by the Archimedes method.

Conclusion

The present study demonstrated that the most accurate method of breast volume measurement is mammography, followed by the Archimedes method. However, when patient comfort, ease of application, and cost were taken into consideration, the Grossman-Roudner device and anatomic measurement were relatively less expensive, and easier methods with an acceptable degree of accuracy.
Scale-by-scale analysis of probability distributions for global MODIS-AQUA cloud properties: how the large scale signature of turbulence may impact statistical analyses of clouds
Authors: de la Torre Juárez M. , Davis A. B. , Fetzer E. J.
Published: March 2011

Abstract. Means, standard deviations, homogeneity parameters used in models based on their ratio, and the probability distribution functions (PDFs) of cloud properties from the MODerate resolution Infrared Spectrometer (MODIS) are estimated globally as function of averaging scale varying from 5 to 500 km. The properties – cloud fraction, droplet effective radius, and liquid water path – all matter for cloud-climate uncertainty quantification and reduction efforts. Global means and standard deviations are confirmed to change with scale. For the range of scales considered, global means vary only within 3% for cloud fraction, 7% for liquid water path, and 0.2% for cloud particle effective radius. These scale dependences contribute to the uncertainties in their global budgets. Scale dependence for standard deviations and generalized flatness are compared to predictions for turbulent systems. Analytical expressions are identified that fit best to each observed PDF. While the best analytical PDF fit to each variable differs, all PDFs are well described by log-normal PDFs when the mean is normalized by the standard deviation inside each averaging domain. Importantly, log-normal distributions yield significantly better fits to the observations than gaussians at all scales. This suggests a possible approach for both sub-grid and unified stochastic modeling of these variables at all scales. The results also highlight the need to establish an adequate spatial resolution for two-stream radiative studies of cloud-climate interactions.
Determining the wavelength of Langmuir wave packets at the Earth's bow shock
Authors: Krasnoselskikh V. V. , Dudok de Wit T. , Bale S. D.
Published: March 2011

Abstract. The propagation of Langmuir waves in plasmas is known to be sensitive to density fluctuations. Such fluctuations may lead to the coexistence of wave pairs that have almost opposite wave-numbers in the vicinity of their reflection points. Using high frequency electric field measurements from the WIND satellite, we determine for the first time the wavelength of intense Langmuir wave packets that are generated upstream of the Earth's electron foreshock by energetic electron beams. Surprisingly, the wavelength is found to be 2 to 3 times larger than the value expected from standard theory. These values are consistent with the presence of strong inhomogeneities in the solar wind plasma rather than with the effect of weak beam instabilities.