bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot Compressive Deformation Behavior of TC4-DT Titanium Alloy
Authors: Li Jing , Zhu Li Wei , Wang Xin Nan , Fei Yue , Shang Guo Qiang , Zhu Zhi Shou
Published: March 2016

Hot compressive experiments of TC4-DT titanium alloy were performed on Gleeble 3500 hot simulator. The influence of hot deformation parameters on high temperature deformation behaviors were investigated, including deformation temperature (938°C~1038°C), deformation degree and strain rate (0.01s-1~10s-1). The results indicated that the peak (σp) and steady-state flow stress (σs) of TC4-DT alloy decreased with the increase of deformation temperature under the same strain rate, especially under a high strain rate. The flow stress increased sharply then decreased and kept invariant finally with the increase of deformation degree. The flow stress increased with the strain rate increasing and exhibited different characteristics in different strain rate range. The optimum conditions obtained based on this investigation of TC4-DT alloy as follows: temperature was 938°C~1008°C, stain rate was 0.01s-1~0.1s-1.
Investigation of Interface in SiC Fiber Reinforced TC17 Titanium Alloy Matrix Composites
Authors: Huang Hao , Li Hu , Wen Mao , Wang Min Juan , Xie Chuan , Huang Xu
Published: March 2016

The investigations were focused on the thermochemical and mechanical properties for interface in continuous SiC fiber reinforced TC17 titanium alloy (nominal composition wt.% is Ti-5Al-2Sn-2Zr-4Mo-4Cr) matrix composites (SiCf/Ti). Scanning electron microscope (SEM), transmission electron microscopy (TEM), and electron probe microanalyzer (EPMA) were applied to observe and analyze the interface reaction product at different heat treatment temperatures. In addition, the reaction rate as well as the relationship between the thickness of reaction layer and time was researched. The interfacial strength at different consolidation temperatures was obtained by means of push-out test, while erosion method was employed to measure the residual stress of composites under different consolidation parameters. The results demonstrate that the thickness of interface reaction layer and heat exposure time is accord with the relationship x=kt1/2+x0, and the interface strength is correlated with the thickness of interface reaction layer, which increases with the intensity of interface reaction. Through the comparison, we find that the inner residual stress of the sample consolidated at 940 °C is higher than that of 920 °C.
Hot-Gas Corrosion Resistance of DD9 Single Crystal Superalloy
Authors: Shi Zhen Xue , Liu Shi Zhong , Wang Xiao Guang , Li Jia Rong
Published: March 2016

The hot-gas corrosion resistance of DD9 single crystal superalloy at 900°Cwas investigated in the present study. The composition and the morphology of corrosion layer were characterized by energy dispersive X-ray analysis spectroscope (EDS) and scanning electron microscopy (SEM). The results show that DD9 single crystal superalloy has excellent hot-gas corrosion resistance and basically obeys parabolic rate law during corrosion test for 100 h at 900 °C. The irregular and prismatic morphology of NiO tightly piles each other on the surface after 100 h corrosion test. The corrosion products possess three layers, outer layer is predominate NiO with a little of Al2O3, middle layer is mixed oxide, and inner layer is sulfide. It was found that flake shaped NiS phase formed in the sulfide layer.
Effect of Microcast-X Fine Grain Casting on the Microstructure and Mechanical Properties of K492M Alloy at 760°C
Authors: Hu Pin Pin , Gai Qi Dong , Li Qing , Tang Xin
Published: March 2016

The effect of Microcast-X fine grain casting on the microstructure and mechnical property K492M alloy at 760°C of was investigated. The results indicated that Microcast-X fine grain casting decreased grain size and dendrite space of γ′ phase and γ/γ′ eutectic. In addition, the element segregation decreased significantly compared to conventional casting technique. Also, the size and distribution of MC carbide were improved. By Microcast-X fine grain casting, the tensile strength increased from 934MPa of conventional casting alloy to 1089MPa and the elongation increased from 1.9% to 5.7%. In addition, the stress-rupture life increased from 28.8h of conventional casting alloy to 72.5h. And the fracture mechanism for the alloys by Microcast-X fine grain casting is trans-granular fracture toughness.
Phase Diagram and Phase Equilibrium Studies on Ultra High Temperature Alloys of Nb-Si-Ti
Authors: Wang Jin San , Kang Yong Wang , Li Chang Rong
Published: March 2016

Due to their high melting temperatures, low densities and excellent high-temperature strengths, Nb-Si-Ti-based ultra high temperature alloys shows great potential for vane materials on the next generation of high thrust-weight ratio aero-engines. In the present paper, the Nb-Si-Ti ternary system was studied, the phase diagram of Nb-Si-Ti and the phase fraction calculated, and the curve of solidification process established. The calculated results provide primary guidance for developing Nb-Si-Ti-X ultrahigh temperature alloys. Moreover, it is very useful as a guide for alloy design and processing development.
Preparation and Properties of HfO2-Y2O3  Composite Coating on the Surface of Iridium Coating
Authors: Zhao Sheng He , Bai Shu Xin , Zhang Hong , Ye Yi Cong , Zhu Li An
Published: March 2016

A “ball milling mixing–low temperature sintering–ball milling smashing” method was applied to produce fine HfO2-Y2O3 composite powders (content of Y2O3 was 7.5 wt.%). The mean diameter of powders was about 0.2μm. By using these powders as raw material, after five cycles of “electrophoresis deposition (EPD)–sintering”, a layer of about 20μm thick HfO2-Y2O3(HYO) composite coating was prepared on the surface of iridium (Ir) coating. The result showed that HYO coating could endure thermal shock for 3 times from 1250°C to 25°C, its emissivity was 0.69 at 400°C and its thermal diffusivity was 0.592mm2/s, which will be a promising candidate applied on the nozzles and wing leading edges of hypersonic vehicles.
Prediction of Ring Rolling Process of PM Ti2AlNb Alloy by Hot Isostatic Pressing Based on Gleeble-3800 and FE Simulation
Authors: Lu Zheng Guan , Wu Jie , Guo Rui Peng , Lei Jia Feng , Xu Lei , Yang Rui
Published: March 2016

Hot workability during hot ring rolling of Ti2AlNb alloy prepared by hot isostatic pressing (HIPing) was studied in this work. Compression results showed that the hot workability of HIP’ed Ti2AlNb was comparable to that of wrought Ti2AlNb. O phase disappeared in compression samples (conducted from 930~1030°C, ~50% total reduction) after deformation which is considered to cause elongation decrease. Finite element method (FEM) was used to predict the temperature/strain distribution during rolling process, and the results indicated that the rolling parameters were very crucial. A sound hot ring rolled billet was successfully fabricated based on an optimized rolling process. Thermal mechanical simulation and FEM are very useful tools for parameters selection during ring rolling.
Microstructure and Mechanical Properties of a New Refractory HfNbSi0.5TiVZr High Entropy Alloy
Authors: Zhang Yan , Liu Yuan , Li Yan Xiang , Chen Xiang , Zhang Hua Wei
Published: March 2016

A new refractory alloy HfNbSi0.5TiVZr was synthesized by induction levitation melting with the aim to achieve an excellent strength and toughness balance of the Hf-Nb-Ti-Zr based alloy. The as-cast alloy with density of ρ=7.75g/cm3 and microhardness of Hv=464 had the microstructure consisting of bcc solid solution with little vanadium rich phase and fine intermetallic phase presented dendritic structure. Mixing entropy and formation enthalpy can explain this behavior. After heat treatment at 1373K for 4 h, no new phase come into being but elements solute more fully. Compressive yield strength of the alloy gradually decreased from 1540MPa at room temperature to 371MPa at 1073K in as-cast state and decreased from 1483MPa at room temperature to 102MPa at 1073K after annealed. Comparing with the similar high entropy alloys, the structure combining silicide and continuous solid phase have a great benefit to the balance of strength and ductility.
Preparation and Welding Performance of Ti–6Al–4V Powder Compact Fabricated by Hot Isostatic Pressing
Authors: Guo Rui Peng , Xu Lei , Wu Jie , Lu Zheng Guan , Yang Rui
Published: March 2016

Powder metallurgy (P/M) Ti–6Al–4V alloy was produced by hot isostatic pressing from pre-alloyed powder in the present investigation. Electron beam welding (EBW) was used for butt joint of P/M Ti–6Al–4V sheets. Microstructure and tensile properties of P/M Ti–6Al–4V welded joint were studied. The results showed that the microstructure of the welded joint had a significant change due to the rapid cooling rate during the EBW process. The microhardness of the fusion zone was higher than that of other areas due to the occurrence of α' martensitic phase. The joint performance (tensile strength) was equal to that of weld matrix, and all of the tensile specimens failed in the base metal. For practical application of P/M Ti-based alloys, the ductility, strength and welding properties of materials could be optimized by proper microstructural design.
Solidification Characterization of K418 Alloy Powders Fabricated by Argon Gas Atomization
Authors: Lu Liang Liang , Zhang Shao Ming , Xu Jun , Sheng Yan Wei , Wang Shan Shan , Zhao Wen Dong , Zhang Jin Hui , Zhao Xin Ming
Published: March 2016

The solidification characterization of K418 alloy powders prepared by argon atomization was studied, and thermal parameters of the alloy powder during solidification process were calculated. The results show that powder morphology is spherical shape, the average diameter of the powder is 55μm, the amount of less 100μm powder is about 90 percent, the solidification microstructure of powders particle surface are dentrite and cellular structure. Decreasing the particle size, the microstructures of particle interior change from dentrite in major to cellular structures, and the structure is more uniformed. The length of secondary dentritic arm and the cooling rate as a function of K418 alloy powders size is established, the cooling rate increases with a decrease of the powder particle size, the cooling rate is in the range of 104K.S-1-106K.S-1.
Flow and Densification Behaviors of Sintered P/F-10C50 Steel under Hot Compression
Authors: Guo Biao , Ge Chang Chun , Xu Yi , Lu Qiu Yan , Zhang Sui Cai
Published: March 2016

The hot deformation and densification behaviors of sintered P/F-10C50 steel were investigated by hot compression tests on Gleeble-1500 thermal mechanical simulator at the temperature ranging from 900 °C to 1000 °C and the strain rate ranging from 0.1 s-1 to 10 s-1. The flow and densification characteristics of the tested specimens at different deformation temperatures and strain rates were studied. The flow stress of the sintered steel persistently increases until the end of the test as the result of matrix and geometric work hardening. The higher deformation temperature and strain rate are conductive to the healing of the pores and promote the densification of the sintered steel, while the higher deformation temperature and lower strain rate impede the densification. The constitutive equation of the sintered steel is established by the means of stepwise regression. The flow stresses predicted by the established constitutive equation are in good agreement with the experimental values, and the correlation coefficient (R) and the average absolute relative error (AARE) are 0.9931 and 3.52%, respectively. These results demonstrate the hot deformation behaviors of the sintered P/F-10C50 steel are excellently predicted by the established constitutive equation.
Analysis of an Axle Failure under Torsional Load
Authors: Li Shu Mei , Yang Jian Jun , Zhang Wei Dong , Chang August , Zhang Cai Xia , Gao Yong Zhan , Wu Ming Liang , Wu Xue Feng , Li Min Xia , Zhang Jian Qi
Published: March 2016

Premature fracture of an axle under torsional load occurred after a tracked military tank had experienced field testing for only 80 kilometers. Visual metallographic examinations were performed with optical microscope (OM) and scanning electron microscope (SEM). The investigation demonstrates that the premature fracture is caused by metallurgical problems inside the axle where the primary and secondary cracks originate, propagate, and eventually result in final catastrophic rupture through torsional fatigue. The failure mechanism is summarized and improvement of the fatigue lifetime for the axle is recommended.
Influence of Surface Conditions on the Fatigue Behavior of A357 Aluminum Alloy
Authors: Jiang Shu Nong , Xu Shi Yuan
Published: March 2016

The influence of surface conditions on the fatigue behavior A357 aluminum alloy was studied in this paper. Four-point bending fatigue tests method were performed to obtain the fatigue strength of A357 cast aluminum alloy specimens with different surface conditions. A joint bearing rig was designed to minimize the experimental error caused by the misalignment associated with a four-point bend test. The results showed that the fatigue strength of specimens with as-cast surfaces was higher those with machined surface roughness of Ra=1.6μm and 3.2μm, while lower than that with Ra=0.4μm. Optical microscope (OM) and scanning electron microscope (SEM) observations, indicating that the fatigue cracks initiate from machined grooves for specimens with roughness of Ra=1.6μm and 3.2μm, while subsurface crack initiates from cast defects inside the specimen with roughness of Ra=0.4. For specimens with as-cast surface, the fatigue cracks initiate from the surface irregularities or cast defects near the surface.
Design and Optimization of the Monochromator for the New Residual Stress Diffractometer
Authors: Liu Xiao Long , Liu Yun Tao , Han Song Bai , Chen Dong Feng , Li Mei Juan , Li Yu Qing , Gao Jian Bo , Yang Lin Feng
Published: March 2016

The monochromator for the new residual stress diffractometer at China Advanced Research Reactor (CARR) was simulated and optimized using SIMRES software. Objected the Fe (211) diffraction peak, the effect of horizontal and vertical curvature of Si (400) monochromator on Figure of Merit was studied to optimize the focusing parameters. With the optimal focusing condition, the influence of wafer thickness, number of wafers, packet height and gap of packets on performance of instrument was calculated consequently and the corresponding geometrical size was fixed. Finally, the design of the monochromator for the new residual stress diffractometer at CARR was completed.
Planning of Energy-Selective Neutron Imaging Instrument at CSNS and its Application Prospect in Materials Science
Authors: Chen Jie , He Lun Hua , Zhang Jun Rong , Wang Fang Wei
Published: March 2016

In order to serve a growing multidisciplinary community beyond the traditional scattering areas, an energy-selective neutron imaging instrument is proposed in the China Spallation Neutron Source (CSNS). The instrument is planned to provide analytical techniques such as state-of-the-art energy-selective neutron imaging, neutron radiography, tomography, polarized neutron imaging, neutron phase contrast imaging, and combined neutron diffraction. Coupled hydrogen moderator (CHM) will be chosen as its neutron source. A flight path of 40 m from moderator to sample will provide good energy resolution better than ~0.4%. Super mirror neutron guide will be used to transport neutron from moderator to aperture selector. Aperture selector with 5 apertures and a set of slits will be used to adjust the neutron beam for different modalities. The best spatial resolution will be 50 μm. Different types of detectors will be needed including high spatial resolution CCD camera, TOF detector, and scintillator detector. With a main emphasis on advanced materials and engineering studies, the instrument will enable 2D/3D mapping of the microstructure, chemical composition, and crystallographic structure (grain size, stress and strain, phase position, texture, and so on). It will also support a broad range of studies in archaeology, biology, biomedicine, geosciences, building technology, manufacturing processes, forensic, and homeland security applications.
Residual Stress Analysis in Quenched Aluminum Alloy Plate Using the Contour Method
Authors: Li Ya Nan , Zhang Yong An , Li Xi Wu , Li Zhi Hui , Wang Guo Jun , Jin Long Bing , Xiong Bai Qing
Published: March 2016

A plate (30mm thick) of aluminum alloy 7085-T76 was quenched into water at room temperature after solution treated at 470°C. The quenching residual stresses distributions were studied by both experimental measurement and FEM (Finite Element Method) simulation. The experimental measurement was accomplished by using the contour method, and the FEM simulation was carried out to verify the experimental results. The experimental quenching residual stress distributions showed the tensile stresses of 74.8MPa ~109MPa in the center part, and compressive stresses of 29MPa-63.6MPa on the surface. The prediction distributions showed the maximum tensile stress of 98.2MPa in the center and the maximum compressive stress of 50.5MPa on the surface. The experimental quenching residual stresses distributions agree favorably with the prediction results. The deviations of the maximum tensile stress were less than 25MPa in the center. The deviations may be attributed to the accuracy of the contour method and the idealization of the prediction model.
Thermodynamic Re-Assessment of the Mn-La Binary System
Authors: Zhu Chao Fan , Lin Shi Dong , Wang Jiang , Rong Mao Hua , Rao Guang Hui , Zhou Huai Ying
Published: March 2016

In this work, eleven Mn-La alloys were investigated experimentally by means of thermal analysis. The temperatures of the invariant reactions in the Mn-La binary system were determined. To confirm whether the liquid miscibility gap exists in the Mn-La system, one key alloy (Mn72La28) was prepared and then checked by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Microstructure observation and composition analysis indicated the nonexistence of the liquid miscibility gap. Based on the experimental results obtained in the present work and the critical review of the available experimental data in the published literature, a set of self-consistent thermodynamic parameters for the Mn-La system was obtained using the CALPHAD method by thermodynamic optimization of the selected experimental data.
Orientation Effects of CH3NH3+ on CH3NH3PbI3 Stability and Photoelectric Properties
Authors: Zhou Jun , Tang Fu Ling , Xue Hong Tao , Si Feng Juan
Published: March 2016

The orientation effects of the organic functional groups CH3NH3+ along [100], [110], [111] and [210] on the stability and photoelectric properties of CH3NH3PbI3 were investigated using first-principles calculations. The results showed that the system energies when C-N bond was along [100]/[210] directions were lower than those while C-N bond was along [110]/[111] directions. The band gap while C-N bond was along [100]/[210] direction was larger than that while C-N bond was along [110]/111] direction. The system energy changed within the range of 0.8 eV, and the band gap changed within the range of 0.05 eV as CH3NH3+ moving along the same crystal direction. The optical properties of CH3NH3PbI3 with the C-N bond along [100] direction were different from those with the C-N bond along [111] direction, while the differences were not obvious. The change trends of optical properties with CH3NH3+ moving for two structures were in agreement with each other. The optical properties indicate that CH3NH3PbI3 is a good light absorber material for thin film solar cells.
Effect of Deformation Homogeneity on Grain Refinement of AZ31 Magnesium Alloys Based on FEA during ECAP
Authors: Xia Yi Wen , Peng Bi You , Zhou Chao , Pan Ren Yuan , Chen Shi Xiong
Published: March 2016

In this study, the deformation process of AZ31 magnesium alloy during equal channel angular pressing (ECAP) was simulated using the commercial software Deform-3D under different extrusion condition (passes and temperatures). To investigate the effect of temperature and deformation rate on grain refinement, the rules of flow and deformation homogeneity and also the extrusion load during ECAP was discussed. The simulation results indicate that the AZ31 magnesium alloy obtain homogenous and larger strain magnitude after 4 passes ECAP at 250°C~275°C. To verify the 3D finite element simulation results, the microstructure in the cross-section was observed. It shows that the grain of AZ31 magnesium alloy is homogenous refined by finite element method (FEM) results, thus the mechanical property is improved.
Size Dependent Bond Length of Metallic Clusters by Considering Bond Number
Authors: Li Hui , Xiao Hao Jie , Wang Jiang , Zhang Hai Xia , Xuan Hai Cheng , Ma Qing Liang
Published: March 2016

In this study, size-dependent bond length of metallic clusters is established by introducing bond number. This model, free of any adjustable parameters, can be utilized to predict the change rule of bond length with size. If the atomic structure of a cluster is known, the size and shape-dependent bond number are obtained. The cubooctahedral structure is taken for simplicity to describe the shape and geometric characteristics of metallic clusters. It is found that the bond length decreases with the decreased size of metallic clusters, which is due to the structure relaxation and enhanced single bond energy. The theoretical predictions are consistent with the evidences of the simulations for Au and Ag clusters. This confirms the validity of taking cubooctahedron structure, even if the simulated Au and Ag clusters are not cuboctahedron ones. This can be expected to other metallic clusters even with other atomic structures.
Numerical Simulation of Centrifugal Casting Process of Large Thin-Wall Ti Alloy Casting
Authors: Shao Heng , Li Yan , Zhao Peng , Nan Hai , Xu Qing Yan
Published: March 2016

Centrifugal pouring is often used in investment casting of large thin-wall Ti castings to promote filling. Shrinkage defects often appear in a Ti casting produced by centrifugal casting. Numerical simulation indicate that shrinkage is caused by these reasons: improper pouring system and thin-wall structure limited feeding of liquid metal from pouring system, and centrifugal force enlarged the shrinkage defects by strengthen feeding of liquid within the casting. Thus centrifugal casting is replaced by gravity casting and a new pouring system is adopted. Obvious shrinkage defects disappear in the new casting process.
Plastic Deformation and Recrystallization of a Ni-Based Single Crystal Superalloy
Authors: Li Zhong Lin , Xu Qing Yan , Xiong Ji Chun , Li Jia Rong , Liu Bai Cheng
Published: March 2016

Plastic deformation and recrystallization of a Ni-based single crystal superalloy were experimentally investigated. Compression and Brinell Indentation were utilized to cause plastic deformation, and thereafter some deformed samples received heat treatment. Surface topography around the indent confirms the anisotropic plasticity of single crystal superalloys. The influential distance below the indent is much larger than that on the indent surface. Microstructural observation by Electron Back-scatter Diffraction (EBSD) shows that it is easier for nucleation and grain boundary migration in the dendritic arms. In addition, the recovery has almost no effect on preventing recrystallization for deformed samples with small plastic strains (around 5%).
Plasma-MIG Hybrid Welding Process of 5083 Marine Aluminum Alloy
Authors: Cai De Tao , Han Shan Guo , Zheng Shi Da , Yan De Jun , Luo Jiu Qiang , Liu Xiao Li , Luo Zi Yi
Published: March 2016

Plasma-MIG hybrid welding and MIG welding of 5083 marine aluminum alloy was carried out. The influences of parameters of welding process on the weldments morphology were investigated in order to optimize the welding process parameters. The macrostructure, microstructure, tensile and bending properties of the optimized joint were studied. The results show that Plasma-MIG hybrid welding not only has a synergistic effect of Plasma and MIG welding but also has a high welding efficiency. Welding speed, Plasma current and MIG current have a significant effect on welding penetration and welding morphology. Meanwhile, the ductility and strength property of weld joint was qualified though the bending test and tensile test. The average tensile strength of weld joint is about 285MPa at room temperature, about 86% of the base metal.
Development of Semi-Solid Die Casting Process Technology for Aluminium Alloy Clamp
Authors: Chen Song , Li Da Quan , Zhang Fan , He You Feng , Zhu Qiang , Li Yi , Cui Hai Xia
Published: March 2016

Compared with traditional liquid and solid processing methods, semi-solid die casting process can apparently overcome shrinkage cavity and porosity defects in castings and high deformation resistance and high residual stress shortcomings in forging parts. Semi-solid die casting process with advantages such as high efficiency and low cost, will become the optimal process for high quality automobile parts. In this study, using the clamp as an example, the author introduced product structure optimization and die design for semi-solid die-casting process of aluminum alloy in a new product development.The Computer Aided Engineering technology was applied to the product structure optimization according to the stress analysis. The optimal mold structure, including cavity layout, gating system, overflow and vent systems, were confirmed based on the die design criteria for traditional die casting, combining with the characteristics of semi-solid forming and the simulation results. The semi-solid aluminum alloy clamp parts with excellent performances were finally developed successfully by means of product structure optimization, die design, parameters optimization of die casting process, and the mechanical properties test of products.The existing parts were optimized to make them more suitable for semi-solid die casting processing. In addition, a reasonable die design specially for semi solid processing was an important guarantee for a successful semi solid product applied in industry. Computer numerical simulation was applied in product structure design for semi-solid die casting, die design, die-casting process optimization and other aspects, to shorten the development cycle of new product, reduce cost and improve efficiency.
Effects of Ultrasonic Vibration on the Welding Process of Friction Stir Welding
Authors: Liu Ye , Lu Sheng
Published: March 2016

Based on the understanding of Friction Stir Welding (FSW) and the effect of ultrasound, the purpose of the paper is trying to find the effective access to reduce the welding resistance and improve the quality of weld during FSW. The best vibration point was first determined through the vibration test system. Then, the thermal cycling, three-force and torque were tested by using paperless recorder and mechanical sensor in heat-power test bench for 4mm thick AZ31 magnesium alloy. The results showed that the periodic vibration took place at the weld under the excitation of ultrasonic vibration, and the frequency of this vibration was as same as the frequency of ultrasonic vibration. The best tracking distance of ultrasonic vibration was 40 mm, and its optimal incident angle was 45°. By applying ultrasonic vibration to FSW, the forward resistance, the axial force and the torque of the tool can be significantly reduced. In addition, the distribution of temperature field was basically consistent with the two conditions, presenting “asymmetrical, non-linear” distribution characteristic. The heating effect of ultrasonic vibration was not obvious, but it was able to make the temperature field of the welding seam become more uniform.
Fast Preparation of Ultrathin FIB Lamellas for MEMs-Based In Situ TEM Experiments
Authors: Wang Hui , Xiao Shang Gang , Xu Qiang , Zhang Tao , Zandbergen Henny
Published: March 2016

The preparation of thin lamellas by focused ion beam (FIB) for MEMS-based in situ TEM experiments is time consuming. Typically, the lamellas are of ~5μm*10μm and have a thickness less than 100nm. Here we demonstrate a fast lamellas’ preparation method using special fast cutting by FIB of samples prepared by conventional TEM sample preparation by argon ion milling or electrochemical polishing methods. This method has been applied successfully on various materials, such as ductile metallic alloy Ti68Ta27Al5, brittle ceramics K0.5Na0.5NbO3-6%LiNbO3 and semiconductor Si. The thickness of the lamellas depends on the original TEM sample.
Effect of Solution Treatment on Microstructure Evolution and Mechanical Behavior of Cu-20Ni-20Mn Alloy
Authors: Xie Wei Bin , Wang Qiang Song , Xie Guo Liang , Mi Xu Jun , Liu Dong Mei , Gao Xue Cheng , Li Yang
Published: March 2016

The influence of solution treatment on microstructure evolution and mechanical behavior of Cu-20Ni-20Mn alloy was investigated by optical microscopy (OM), X-ray diffraction (XRD) and hardness test. The results revealed that both solution temperature and holding time had effect on the grain growth behavior. The grain growth activation energy was determined by grain size of Cu-20Ni-20Mn alloy for different heat treatment temperatures and periods. With increasing temperature of solution treatment, the second phase is gradually dissolved into the Cu-rich matrix, and the lattice parameter of the matrix solution treated at 1173K for 0.5 h was about 3.668 Å. The hardness of the solution-treated alloy was lower than that of hot forging, and the hardness value decreased with the increase of solution temperature, which may be attributed to grain size. The hardening ability, corresponding to the Hall-Petch relationship, decreased linearly with D-1/2.
Discharge Enhancement Effect of Inorganic Nanometer Spark Plasma Sintering Aid
Authors: Li Hao Feng , Wang Ming Gang , Zhao Zhan Kui
Published: March 2016

CaF2 inorganic nanometer powder particles were used as sintering aid to sintering good conductive Fe-6.5Si alloy. By a physical method, CaF2 inorganic nanopowder particles were made with a granularity of 15-30 nm assembled between micron-sized Fe-6.5Si powder particles prepared by gas atomization. 6.5 % Si high silicon steel were fabricated by spark plasma sintering (SPS) with varying contents of CaF2. The discharge enhancement effect of CaF2 inorganic nanospark plasma aid is confirmed. The initial sintering temperature and the final sintering temperature were decreased by 75 °C and 70 °C respectively with 0.5 % CaF2 inorganic nanopowder aid. In the case of reduced 60 °C, the higher density for the particles with the addition of CaF2 was observed compared with without CaF2. When the nanopowder was 2%, sintering performance decreased. The study indicates that sintering pressure has an enormous effect on the Fe-6.5Si sintering effect.
Investigation on Grain Size Effect of Rolling Texture in Copper
Authors: Jiang Yao , Wang Jing Tao , Wang Yue , Yin Jian
Published: March 2016

Cold rolling (CR) was conducted on coarse grained (CG) and ultrafine-grained (UFG) coppers, obtained by 1 and 8 passes in the equal channel angel pressing (ECAP), to investigate the effect of grain size on rolling texture. The microstructure was refined to UFG (~420 nm) with the ECAP pass increased to 8, while only band-like CG microstructure was observed in the 1 pass processed copper. The influence of the texture before CR could be excluded as the crystallographic texture kept similar for different ECAP pass. Pole figures (PFs) showed that the shear texture introduced by ECAP was replaced by rolling texture after CR. Furthermore, the rolling texture was a kind of classical copper-type for the CG copper, while a brass-type rolling texture was observed in the UFG copper. TEM results confirmed that the deformation nanotwins were only observed in the UFG copper, while the microstructure of CG copper was further compressed and subdivided. It indicated that the observed differences in rolling texture component and density might be contributed to the grain size effect which resulted in different deformation mechanism and grain subdivision behavior.
Residual Strength Analysis of Oil Tubes with Corrosion Defect
Authors: Xia Meng Ying , Duan Qing Quan , Liu Xiao Ben , Zhang Hong
Published: March 2016

Corrosion defect in oil tubes is one main threat for the safety production of oil field. The corrosion defect in the tube will cause stress concentration and even lead to failure. The injection of CO2 widely used during the recent years in oil fields, making the corrosion problems more severe. In this study a finite element model for the residual strength analysis of oil tube with corrosion defect was established by the programing language APDL. Based on the actual data of one oil well in Tahe oil field in China, the sensitivities of the axial length, circumferential width, radial depth of the corrosion defect, the internal pressure and axial force on the residual strength of the tube was examined in detail. The proposed method can be referred in the safety evaluation for oil tubes with corrosion defect.
Semi-Active Method of Motion Stabilization Applied to Mechanical System with the Constant Reaction Force Vibroisolation (CRF) – Model Study
Authors: Dobry Marian Witalis
Published: March 2016

The use of the CRF vibration isolation system with zero natural frequency for machinery and equipment in the Earth's gravity field requires stabilization of motion because of its high susceptibility. For this purpose, an additional spring element with a low elastic coefficient “k1” and a semi-active damper “c (t, x, v, ff)”, was included in the vibration isolation system and parallel-attached to the CRF vibroisolator. Investigation of the effect of the additional element to stabilize the motion of the mechanical system was carried out by a numerical simulation of its motion. The simulation was based on a physical and mathematical model of the system including the spring and the magnetorheological damper (MR). The mathematical model was then used to develop a dynamics simulation program of the system and conduct simulations using sample data in order to study transitional processes and their stability. Simulation results indicate a substantially improved stability of motion in the system. Stability studies of motion were also combined with an analysis of power distribution in the system. The aim of this study was to determine energy efficiency of the system developed, defined as the ratio of the RMS power of the exciting force to RMS power of the elastic force. The resulting energy efficiency of CRF vibroisolation was equal to 5168 for a simulation period of 6 seconds.
Shaping the Dynamic Characteristics of Military Special Vehicles
Authors: Machoczek Tomasz , Mężyk Arkadiusz , Duda Sławomir
Published: March 2016

The article presents a motion dynamics model of a sample military special vehicle, two suspension control algorithms and the results of three different numerical experiments that have been conducted. The applied measure of appraisal was the comparison of the amplitudes of displacement, speed and acceleration – both linear (in the vertical direction) and angular (in the longitudinal and transverse planes) in time.
Design and Pre-Implementation of Micro-Movements Sensor with Magnetic Shape Memory Material
Authors: Flaga Stanisław , Dominik Ireneusz
Published: March 2016

The paper describe design and built the micro-displacement sensor demonstrator with the use of the active material MSMA. It shows the selection of individual components of the system and its construction. Article presents problems arising during experiments and suggests possible ways of their solution. Shortly characterized other technologies, which are used in commonly used micro-displacement sensors. It also formulated a few comments that may simplify the further development of this project.
Advanced Production System Management for Offshore Gas Condensate Field: Challenges and Successes
Authors: Fadel A. , Safwat H. , Dabbour M. , Belli A. , Darwish H. , Nagy M.
Published: March 2016

The main objective of this paper is to identify any current and future bottlenecks in the production system while honoring operational constraints on wells, production separators, pipelines, and total field gas/liquid processing capacity. It also concerns with identifying any flow assurance issues taking in consideration different field development scenarios for an offshore gas condensate field in the Mediterranean (Abu Qir Field). Liquid loading in gas wells occur when the gas flow rate falls below a critical rate due to reservoir depletion where the accompanying liquids cannot be lifted to surface. Such liquid accumulations at the wellbore can cause the gas well to cease production eventually. Severe slug flow (i.e., terrain-dominated slug flow) was studied. Severe slug flow is characterized by extremely long liquid slugs generated at the base of the vertical riser. This phenomenon occurs at low gas and liquid flow rates and for negative pipeline inclinations.

To evaluate future development options and to provide a monitoring tool and realistic results, a multi-disciplinary Petroleum Engineering study was carried out. Unknown reservoir parameters were estimated using the modern production data analysis method, which was also used as a reliable forecasting tool. Steady state multiphase flow simulator and the forecast from production data analysis and numerical reservoir simulator were used to identify any current and future bottlenecks and also optimize the production taking in considerations field's constraints. Transient multiphase flow simulator was used to identify and mitigate transient flow assurance issues i.e. liquid loading in gas wells and slugs in the pipelines. Other scenarios were also studied include: platform start-up and shutdown; production Ramp up due to the introduced platform; and Hydrates no show time due to any shutdown. This helped us to determine the proper design envelope of the new system.

This integrated workflow helped in optimizing the current operating conditions and decreasing field operating cost by increasing the current gas production rate by 6%. We managed to prevent the decline in reserves by more than 10% in the future caused by production system bottlenecks. Choke size for each well was identified honoring existing constrains (reservoir pressure, flow velocity limits, etc.) to increase field gas production. Outlet pressure of a surface network was maximized in order to minimize operational costs of gas processing while maintaining required gas production level. Different scenarios were carried out to come with procedures to prevent and mitigate production instabilities and also decreasing the deferred production.

This work can subsequently propose an integrated field management workflow on addressing various production issues especially in case of limited data availability and how different domains can co-operate to reach the optimum operating scenarios.
Hybrid Bit Produces Breakthrough Performance in Heterogeneous Formations in China
Authors: Miao S. , Blackman M. , Luo J. , Luo L.
Published: March 2016

During the last seven years in the Changbei gas wells of China, operator utilized heavy-set roller-cone bits in the 8 ½-in.lateral wells because of the hardness and abrasiveness of the rocks. After the project moved from the southern to the northern part of the block, the formation became more heterogeneous, and the ROP of the roller-cone bits dropped 40% on average. This challenged the project economically because 60% of the operating time is spent drilling this interval.

To improve performance in these wells, a hybrid bit combining PDC and roller-cone was proposed. The intention was to improve ROP through the hard-to-drill intervals in the northern block and reduce bit consumption. Claystone and other soft and plastically behaving rocks are drilled farther using PDC bits; hard and abrasive sandstone, meanwhile, are drilled farther using roller-cone bits.

Field trials in Changbei gas wells were very successful. The client saved multiple standard Tungsten Carbide Insert (TCI) runs and drilled 100% farther, achieving a rate of penetration (ROP) two times faster than the best TCI bit run in the same well and area. Stable tool face control was also observed because of the lower torque fluctuations which enabled the operator to reduce the amount of time sliding by up to 15% versus using offset bits. The paper will present an analysis of the drilling data from the field and provide a detailed description of the application's achievement by comparing the performance of the roller-cone, PDC and hybrid bits.

The paper will describe the planning and operational execution of drilling an 8½-in. horizontal lateral with a hybrid bit in a challenging application, and conclude with the technical and economic benefits and the potential of the new drill-bit technology.
Analytical Modeling of Nanofluid Injection to Improve the Performance of Low Salinity Water Flooding
Authors: Yuan Bin , Moghanloo Rouzbeh Ghanbarnezhad , Zheng Da
Published: March 2016

Low salinity water (LSW) has been confirmed as an efficient improved oil recovery technique. Accompanying this technique, however, induced fines migration by chemical environments of low salinity has posed great challenges to well injectivity and productivity. It has been shown that nanoparticles can effectively enhance attractive forces between fine particles and grain surfaces through changing the surface zeta potentials of fine particles, and significantly mitigating formation damage caused by fine particles and clogging pore-throats. In practice, this paper not only provides an analytical model to confirm the feasibility of nanoparticle application to reduce fines migration, but also presents improvement analysis of LSW flooding performance with nanoparticles application.

The paper introduces an axisymmetric flow model and Method of Characteristic (MOC) to study the effects of nanofluid-slug preflush to improve the displacement performance of low salinity injections. The interplay among nanoparticles, fines, and rocks is described by a physical-chemical reaction model. The maximum retention concentration of fine particles is derived in two-phase flow. A new formulation for fraction flow function considering fines migration in water-phase is introduced. The semi-analytical solutions of low salinity water flooding without/with fines migration and nanofluid pre-treatment are derived and verified by numerical simulations.

The results indicate that: 1) as the low salinity water saturation increases, the detachment of fines attached on rock grains exaggerates. The majority of fines detachment and pressure loss occur in the region near the well; 2) the induced fines migration by low salinity water can delay the time of water breakthrough, and extend the duration of no-water production. However, fines migration can also lead to decline of well injectivity; 3) at the early life of water flooding (before water breakthrough), the recovery factor of conventional water flooding is larger than that of low salinity water flooding. At the late life (after breakthrough), the recovery factor of low salinity water flooding exceeds that of conventional water flooding; 4) nanofluid pre-treatment prior to the injection of low salinity water accelerate the breakthrough of injected water, and decrease the injection pressure drop to improve well injectivity. In this paper, the optimal nanofluid treatment range is 0.1, which takes advantages of low salinity water to enhance oil recovery, and prevent decline of well injectivity as well.
Self-Plugging Technology of Microcrack with Water in Cement Sheath
Authors: Bu Yuhuan , Liu Huajie
Published: March 2016

Cement is the main material used to seal wells which are drilled for the production of oil and gas. However, many well operations could induce cement sheath to crack and hence, lose zonal isolation. The research objectives in this paper are designed to realize the application of superabsorbent polymer (SAP) in well cement to plug the microcrack.

Since SAP is highly reactive with water, if SAP is used directly, the cement slurry will have a too high viscosity for pumping in favorable conditions. Therefore, SAP microspheres which were coated were applied. The method of manufacturing quantitative microcrack was established by using the chisel and transparent plastic tube, and the self-designed instrument was taken to test the self-plugging performance of microcrack. Based on the percolation theory, the percolation analysis of microcrack plane flow was carried out. The distribution model of coated SAP microspheres in cement paste was established, which could ensure SAP microspheres exist in any microcrack plane.

Finally, the gypsum-chitosan-gypsum coated SAP is proposed. Microscopic analysis and percolation theory are combined to research the plugging microcrack mechanism. And according to the exact analytical solution of plane percolation threshold, the dosage threshold of coated SAP microspheres which can realize the self-plugging performance of microcrack is 28.40%. The cement slurry whose basic performance met the demand of cementing engineering was developed to test the self-plugging performance of microcrack with water, and the results show that when the dosage of coated SAP microspheres is higher than the threshold, microcrack could be plugged.

In this paper, the percolation theory was first used to design the cement slurry. The application of coated SAP can effectively seal the microcrack in cement sheath, which is of great significance to guarantee the long-term sealing performance of cement sheath.
Fracture Characterization in Basement Using the Latest Generation of LWD Sonic and Resistivity Image Logs
Authors: Dac The Nguyen , Thien Kim Nguyen P. , Le Duy Cao , Tuan Anh Truong , Dang Khoa Chau , Ahmed Aqil , Taesoo Kim , Rehman Sadu-ur , Thai Ha Phung , Anh Pho Le
Published: March 2016

Today, fractured basement is becoming an important contributor to the petroleum industry. However, drilling into the granitic basement reservoir is challenging because of the severe shocks and vibrations and the high requirement for accurate detection of productive fractures. Logging-while-drilling (LWD) technology has quickly adapted to respond to these challenges. The development of new LWD sonic and electric image tools supports an integrated methodology for reservoir characterization and fluid identification, which are critical for success.

The new methodology takes advantage of the latest technology of LWD resistivity image logs and LWD sonic acquisition; the processed high-resolution resistivity images enable the identification of borehole breakouts, natural or induced fractures, vugs, and dips, and Stoneley measurements from the LWD sonic tool enable analysis of the producibility of fracture system with the sonic fracture technique. The integrated methodology combines the strength of the two independent methods to give a comprehensive characterization of the fracture systems.

Analysis from LWD sonic and resistivity images provide location and characters of faults or fractures (open/closed). Results from the analysis are also important input for the production and perforation planning. The case history in this paper shows excellent results from the integrated fracture evaluation with LWD sonic and resistivity image logs. In this case study, fracture database for well design and field development is updated with the result obtained from the well.

It is the first time of combining latest generation of LWD sonic and LWD resistivity imaging logs in Vietnam, essentially this sets a benchmark in the fractured basement characterization. Numerous basement reservoirs are present in Vietnam and worldwide. This advanced technology opens opportunities for fracture evaluation in basement reservoirs using LWD technology.