bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Material-Cutting with Electro-Hydraulic Servo Synchronization Control System for Large Band Saw Equipment
Authors: Chen Guo Jin , Ni Jing , Liu Tin Tin , Chen Hui Peng , Xu Ming
Published: March 2013

Aiming at the cutting for various kinds of material, in order to solve the problems that the present large band saw equipment at home is poor in the synchronization of the sawing feed and is lack of the dedicated NC system, the paper introduces the electro-hydraulic servo drive and digital control technologies, researches the synchronous servo drive and cutting force feedback control technologies, and develops the sawing machine’s control system based on the above technologies. The NC system has been applied in the CNC band saw equipment of the large Portal style. The saw frame uses the structure driven synchronously by the dual hydraulic cylinders in order to guarantee the accuracy of the feed motion. The control system driven by the electro-hydraulic servo synchronization detects the implementation of a two cylinders and does the displacement feedback to achieve the movement synchronization on both ends of the portal frame using the synchronous control strategy. That ensures the movement accuracy for the CNC band saw equipment of the large Portal style and improves the cutting accuracy and efficiency of the equipment.
Study the Stability of Bending-Torsional Coupled Vibration of a Rotor System with a Crack and Variable Perturbation Method
Authors: Wang Chang Fa , Wang Feng Lan
Published: March 2013

The differential equations of bending-torsional coupled vibration have been established with a switching crack for a Jeffcott rotor system with a transverse crack as the research object. Variable perturbation method has been used to study the stability of bending-torsional coupled vibration of a rotor system with a crack. The theoretical result shows that, when it is close to the natural frequency of 2 times, 3/2 times and 1 times, unstable vibrations exist and conditions of stable vibration. According to the above order, unstable region becomes narrow. While in 1/4 times, 1/6 times, the system is stable. The conclusions provide valuable theoretical basis for a crack rotor system in the real working conditions when corresponding measures need taking.
Research on Photocatalytic Degradation Kinetics of S-Doped TiO2 to Phenol
Authors: Yu Jun , Shan Min Jie , Qiu Ling Feng
Published: March 2013

S-doped TiO2 nanomaterials were prepared via hydrothermal synthesis method using tetrabutyl titanate. Kinetics of S-doped TiO2 catalyzing phenol was researched by analysising the influence of initial phenol concentration, initial phenol pH value on photochemical catalysis speed. The results indicated that the value of K decreased with the rising of phenol concentration. The influence of initial solution pH was exsiting an optimal value. When pH value was 4, photocatalytic rate was maxium, corresponding K was 0.17983 min-1.
Design of Controller in Electrical and Electronic Engineering Based on Dual Micro Controller Units for a Brushless DC Motor
Authors: Rang Yu Qi , Xiong Hao , Xiang Dong , Wu Qiang , Meng Guang Wei , Yang Zhan Qing
Published: March 2013

The paper presents a design scheme of a BLDC motor control system based on dual MCUs communication for electrical and electronic application, discusses the rotor position detection circuit, drive circuit, protection circuit, velocity measurement circuit, and dual MCU control circuit, and gives the hardware circuit and the block diagram of software program. It is proved that the design is practical and reliable.
A Modified Maximum Power Point Tracking Algorithm under Partial Shading Conditions
Authors: Sun Bo , Zheng Jian Yong
Published: March 2013

Photovoltaic array output characteristics under partial shading conditions have multi local maximum power points, but traditional maximum power point tracking methods failed to identify global maximum power point. Output characteristics of shadowed PV array under different illumination were simulated by Matlab software. The rule between voltage of possible local maximum power point and the open circuit voltage was summarized. According to this rule, a modified algorithm based on the Incremental Conductance method was put forward. Simulations results indicated that the proposed MPPT algorithm can accurately track the global maximum power point under uniform illumination and partial shading conditions. It can improve the efficiency of PV system.
Prediction Model for the Boiler NOx Emission with Material Properties Based on the Artificial Neural Network
Authors: Sun Bao Min , Wang Ding Hui , Yang Bin , Zhang Shou Heng , Kong Ling Yu
Published: March 2013

This paper establishes the prediction model for the NOx emission with Material Properties based on the artificial neural network,and predicts the NOx emission before and after the borler’s combustion reform .First, this paper analyzes the NOx formation mechanism. Then,this paper establishes the prediction model for the NOx emission with Material Properties based on the artificial neural network,which uses the main factors of influencing NOx formation as input variable. At last , this paper trains new samples again,and predicts the boiler NOx emission after the boiler’s low NOx combustion reform.This paper demonstrates that the model is effective for predicting boiler NOx emission before and after the boiler’s low NOx combustion reform.
Situ Testing Study on Jacking Force of Manual Pipe-Jacking with Engineering
Authors: Yang Zhuan Yun , Yi Li Yun
Published: March 2013

Manual rectangle pipe-jacking technology is adopted to jack the pre-fabricated hollow box girder slowly and evenly into the load bearing wall of masonry structure, and then core beam is poured to form a whole, therefore, the constructions will be gradually located at a “tray” with enough rigidity, which solves the structural damage caused by inadequate bearing capacity of foundation soil or unsymmetrical support. In actual masonry structure protection, there have been successful examples where such technology is used, however, till now its related fundamental problems have not been researched yet. In this paper, based on study of on-site actual measurement, its fundamental is introduced, such items as action mechanism of box girder and soil body, calculation of jacking force and its influencing factors, and more, are discussed and empirical formula for calculation of jacking force is presented.
Optimization of a Thermoelectric Air Conditioning Systems
Authors: Machado da Silva Jamir , da Silva Renan Eduardo , Camargo José Rui , Godoy Junior Ederaldo
Published: March 2013

This paper studies the optimization of a thermoelectric cooling system of air. Based on both results obtained experimentally and from a mathematical model, we evaluated the available features of thermoelectric modules and parameters subject to optimization. In the thermoelectric cooling air process based on the effect discovered by Jean Peltier Charles Athanase in 1834, when an electrical current is conducted through a semiconductor junction between two materials with different properties, heat is absorbed and dissipated. Thermoelectric modules are made of semiconductor materials and sealed between two plates. According to the shape of the plate, the current flow cools the one hand and the other is heated. The most important parameters to evaluate the efficiency of the thermoelectric cooling is the coefficient of performance, the rate of heat transfer and temperature difference between the maximum possible to the cold and hot sides of the thermoelectric module. In this evaluation were used thermoelectric modules and heat sinks, commercially available temperature sensors and a software for obtaining, storing and comparing the data. The prototype auxiliary allows the surface temperatures of thermoelectric modules of the hot and cold sides, the air inlet and outlet temperatures of the heat sink sides of the hot and cold air flow, the voltage and the electrical current to be applied to the modules. A simulation is performed using two air flows at a speed controlled for the hot and cold sides of the module and a set of tests for various modules, i.e. one, two, three and four coupled in parallel. Using this system, the performance data is analyzed making it possible to check the power, voltage and electrical current to maximize the coefficient of performance of the system.
Heat Conductivity of Metallic Hollow Sphere Structures: Numerical Simulation and Experimental Validation
Authors: Araújo Manuel António Ferreira , Merkel Markus , Öchsner Andreas
Published: March 2013

Heat conductivity is a well-known energy transfer method and it is here applied to the study of metal foams and laser processing. Metallic hollow sphere structures (MHSS), a relatively new group of advanced composite materials, combine the advantages of cellular metals without major scattering of their material parameters. They are characterised by high geometry reproduction leading to relatively constant mechanical and physical properties.The laser processing technology provides not only a laser cutting but also a laser soldering procedure. Within this work a laser cutting process is applied to MHSS. Laser beam cutting is a highly efficient technique to cut materials, because the relatively small amount of heat affects only a small heating zone.Numerical simulation is used in order to define proper process parameters for a large variety of MHSS. The finite element method based simulation covers material parameters as well as process parameters like the cutting velocity. Heat conduction and convection are taken into account and the phase change from solid to liquid state as well. Within the simulations the concept of representative volume element (RVE) is applied. The temperature distribution is the fundamental result.
Cross-Injection Film Cooling on a Curved Surface with or without a Vortical Flow in the Mainstream
Authors: Wu Pey Shey , Chen Kun Yu , Lin Yi Hung
Published: March 2013

Liquid crystal thermography with steady-state experimental method is used to investigate the effectiveness of two-row, cross-injection film cooling on a concave or convex surface. One leg of vortices of a delta wing is used to realize the interaction mechanism between the vortex generated by the cross-injection coolant and the secondary vortex of the main flow. The secondary flow generated by the delta-wing vortex generator produces upwash or downwash motion when sweeping over the film injection holes. In the experiments, the cooling hole diameter, hole-to-hole distances, and an included angle of 120 degrees are fixed, while the main flow Reynolds number, sense of mainstream vortex, and the coolant-to-main flow blowing ratio are varied. Because the cross-injection coolant generates a counter-clockwise vortex (viewed from upstream), results show that when the mainstream vortex has a sense of rotation opposite to that of the cross-injection vortex (i.e. an upwash mainstream vortex), the effectiveness is increased. On the other hand, same sense of rotation in both vortices (i.e. a downwash mainstream vortex) decreases the effectiveness. Both the convex and concave curvatures hamper the attachment of cross-injection coolant to the surface, resulting in a reduction in film cooling effectiveness. The effect is more influential for the concave surface.
Numerical Analysis of Temperature Profiles in a Hollow Circular Cylinder by Alternative Direction Implicit Method
Authors: de Campos M.D. , Romão E.C. , Mendes de Moura L.F.
Published: March 2013

Several methods for numerical solution of heat transfer process have been developed exploiting various discretization techniques. Among these, the Alternating Direction Implicit Methods have the advantage of being unconditionally stable and only need to solve a sequence of tridiagonal linear systems. In this work, it is used in the heat transfer simulation in one quarter of the hollow circular cylinder in an unsteady state, considering the pre-set inner radius and different discretizations of the mesh. The temperature profiles are presented and the error analysis is carried out.
Effects of Sintering Time and Atmosphere on Mechanical Properties of Injection Molded Tungsten Alloy
Authors: Lamlerttham Jittrabhanu , Wila Pongsak , Morakotjinda Monnapas , Krataitong Rungtip , Vetayanukul Bhanu , Tongsri Ruangdaj , Charoensuk Jaruwat , Saito Yoshio
Published: March 2013

Tungsten is a promising refractory metal suitable for applications in which wear resistance, thermal stability and high weight are needed. In this work, the tungsten feedstock (94wt%W with balance of Ni-Cu-Co alloy) was used to form tensile test specimens by using metal injection molding (MIM) process. The molded specimens were debinded by catalytic debinding technique to convert to the brown specimens. After debinding, the brown parts were sintered under vacuum atmosphere (10-5 bar) with varied sintering times at sintering temperature from 1350 to 1450°C. The specimens sintered at 1450°C for 3 hours provided optimum sintered density and mechanical properties. The results showed that mechanical properties of the specimens sintered at 1450°C dramatically decreased when sintering times were longer than 3 hours. The specimens sintered at 1450°C for 8 hours showed brittleness. Physically, inferior mechanical properties were attributed to wettability and porosity of the binder phase. Chemical analyses were performed with the sintered W-(Ni-Cu-Co) specimens by using energy dispersive spectroscopy with mode of quantitative analysis. The specimens sintered at 1400°C for 3 hours showed high W content (28.95 wt. %) dissolved in the Ni-Cu-Co binder. However, penetration of the liquid binder was incomplete. The specimens sintered at 1450°C for 3 hours showed higher W content (34.28 wt. %) dissolved in the Ni-Cu-Co binder (with lower Cu content). Distribution of Cu was uniform across the whole specimen. Wetting of the liquid binder on W grains was complete without porosity. The specimens sintered at 1450°C for longer than 3 hours showed less W content (< 28.95 wt. %) dissolved in the Cu-depleted Ni-Co binder. Porosity was observed in the binder phase and in W grains. Sintering between W grains was also observed. Effects of different sintering atmospheres were also investigated. It was found that increasing the sintering chamber pressure caused detrimental effects on both physical and mechanical properties of the sintered tungsten specimens. In addition, nitrogen atmosphere gave similar results to those for increased chamber pressure.
Experimental Determination of Isothermal Section at 900°C in the Fe-Nb-V Ternary System
Authors: Liu Chang Jiang , Li Yan Jiao , Guo Zhi Qing , Lv Qiu Juan , Xie Fang , Zhu Ya Hong
Published: March 2013

The phase equilibria in the Fe-Nb-V ternary system were investigated by means of optical microscopy, electron probe microanalysis. One isothermal section in the Fe-Nb-V ternary system at 900 °C was firstly experimentally established. Present experimental results indicate that: (1) there is a large (Nb, V) continuous bcc solid solution; (2) there are the larger solubilities of V in the FeNb and Fe2Nb phases. The newly determined phase equilibria in this system will provide important support for the development of microalloyed steels.
Investigation on Thermal Conductivity of Low Concentration AlN/EG Nanofluids
Authors: Li Yan Jiao , Liu Chang Jiang , Guo Zhi Qing , Lv Qiu Juan , Xie Fang
Published: March 2013

The thermal conductivity of AlN/EG nanofluids was investigated by transient hot-wire method. Experimental results indicated that the thermal conductivity of AlN/EG nanofluids increase nearly linear with the increase of nanoparticles volume fraction, and the results can’t be predicted by conditional Maxwell model. The effect of temperature on effective thermal conductivity of AlN/EG nanofluids was investigated. Result indicated that the thermal conductivity of AlN/EG nanofluids increased with the increase of temperature.
Investigation on Affecting Factors of Vibration in Milling Harden Steel Assembled with Different Hardness
Authors: Wang Yang Yu , Zhou Hao Dong , Wen Dong Hui , Ji Shi Ming , Wang Hui Qiang
Published: March 2013

The milling vibration affects machined surface quality and the size of the error, and has an important impact on the machining accuracy. This paper studies the different cutting parameters on cutting conditions on milling vibration during ball end milling Cr12MoV hardened steel assembled with different hardness steels, and use LMS. Test. Lab software to analyze the vibration signal on the condition of different spindle speed milling direction, axial depth of cut, and the vibration signal of transitional zone and the non-transitional zone are compared, providing the basis for a reasonable choice of milling parameters.
Dynamic Characteristic Calculation of CNC Machine Tool’s Base Based on FEM
Authors: Deng Xiao Lei , Wang Jian Chen , Zhou Zhao Zhong
Published: March 2013

Base is a main component of CNC machine tool, so its dynamic characteristics impact on machine tool’s machining precision and stability directly. However, the traditional analytic way cannot finish the accurate and complete calculation and analysis. So it is very necessary to make FEM dynamics research on base of machine tool. This paper employs FEM modal analysis to research the free vibration of base which is undamped. And then we can get the nature frequencies of the base’s first six modal, there are 407.79 Hz, 430.47 Hz, 501.23 Hz, 623.63 Hz, 626.51 Hz and 661.19 Hz, respectively. In addition, the first six modal shapes are also obtained. The forth frequency and the fifth frequency are much closed, so they can be considered the multiple roots for the vibration equation. The research results can provide theoretical basis for fault diagnosis，safety operation and vibration control，and the important parameters are useful for structural improvement and optimization design of the NC machine tool．
Extensions of Electron Diffraction Based Techniques in Crystallographic Characterization
Authors: Zuo Liang , Li Zong Bin , Zhang Yu Dong , Esling Claude , Zhao Xiang
Published: March 2013

Abstract. With the advance of electron diffraction techniques in individual orientation analysis, traditional crystallographic characterization methods could be simplified, thus offering chances to develop some new approaches. In recent years, our group has devoted to working on possible extensions of the SEM and TEM based techniques for crystallographic analyses on a microstructure- and orientation-specific level. Several methods are illustrated in this paper, including the determination of dislocation type and Burgers vector without recourse to the traditional g.b invisibility condition, the identification of twinning mode and complete twinning elements for any crystal symmetry that requires minimum initial data input, and the characterization of specific interface plane or slip plane using only one sample observation plane instead of two perpendicular sample planes. These new extensions of characterization methods have proven to facilitate the related microstructural examinations.
Modelling the Evolution in Microchemistry and its Effects on the Softening Behavior of Cold Rolled AlFeMnSi-Alloys during Annealing
Authors: Hersent Emmanuel , Huang Ke , Friis Jesper , Marthinsen Knut
Published: March 2013

A dedicated diffusion controlled precipitation model for AlMnFeSi-alloys, based on classical nucleation and growth theory, has been implemented and coupled to a phenomenological softening model accounting for the combined effect of recovery and recrystallization during annealing after cold rolling. The result is a fully coupled precipitation and softening model which in principle is capable of accounting for variations in solute levels and size and volume fraction of dispersoids and their interaction with the softening behavior during annealing.
Modelling Dynamic Recrystallization in FCC Metals Employing Thermostatistics
Authors: Galindo Nava Enrique , Rivera-Diaz-del-Castillo Pedro
Published: March 2013

Theory for describing the conditions leading to dynamic recrystallization in FCC metals is introduced. The approach also describes stress-strain curves when this process occurs, and is unique in incorporating the effects of strain rate and temperature employing only physical parameters as input. The novelty of the approach stems from incorporating an incubation period in the equations describing the progress of dislocation density with strain; beyond such incubation dislocation free grains form. The energy barrier to ignite grain growth is expressed as a function of the strain energy stored on the material and a statistical entropy contribution due to the degrees of freedom available to a dislocation for annihilation. The incubation strain is obtained by performing an energy balance between the stored energy on the subgrain boundaries, the slip energy of boundary migration and the interfacial energy required for grain nucleation. The application of this work to pure Cu and Ni has lead to transition maps in temperature-strain rate space indicating the conditions for dynamic recrystallization occurrence.
Microstructure and Texture Evolutions in a Short-Time-Annealed Interstitial-Free Steel
Authors: Jia Juan , Zhu Wei Wei , Gao Heng , Dai Li Bin , Li Meng , Song Xin Li
Published: March 2013

One kind of high strength interstitial free steel sheets are annealed in a salt bath at 810 C for different times (1-30 s). The microstructure and recrystallized texture evolution during annealing are investigated using the optical microscopy and the Electron Back Scattered Diffraction technique. The results show that beginning and finishing of recrystallization are observed in the sample annealed at 810 C for 8 and for 20 s, respectively. The recrystallized grains nucleate in the order of ‹111›//ND, ‹110›//ND and ‹100›//ND. Recrystallized grains with ‹111›//ND orientation nucleate firstly in the ‹111›//ND deformed grains as well as at their boundaries and grow up by consuming the ‹111›//ND deformed grains at the initial stage of recrystallization. The ‹111›//ND recrystallized grains grow up by depleting the remained formed ‹100›//ND grains after the full consumption of the ‹111›//ND deformed grains. The overall recrystallization texture is mainly the ‹111›//ND component in the steel.
Activation Energy for Recrystallization in Fe-3wt.%Si Alloys with Different S Contents
Authors: Mao Wei Min , Zhang Mao Hua , Yang Ping , Wang Kai Ping
Published: March 2013

The recrystallization behaviors of 60% rolled Fe-wt.3%Si and Fe- wt.3%Si-Mn-S alloys containing coarsen MnS particles were observed in temperature range 600°C~1000°C. The activation energy for recrystallization was determined according to an Arrhenius type of relationship. It was found that the activation energy in the temperature range 600°C~750°C was much higher than that in the temperature range 850°C~1000°C. Thermo-mechanical calculation indicates that there are hardly precipitation behaviors of MnS particles in 600°C~1000°C. Fe3C will precipitate below 650°C and Cottrell atmosphere will form just above 650°C, which induces dragging effect against the boundary migration during recrystallization and increase the activation energy. The activation energy determined was about 99kJ/mol or 217kJ/mol in Fe-3%Si alloy and 91kJ/mol or 220kJ/mol in Fe-3%Si-Mn-S alloy for the recrystallization in high temperature range of 850°C~1000°C or low temperature range of 600°C~750°C respectively.
Effect of Niobium on Static Recrystallization Characteristics of TWIP Steels
Authors: Somani Mahesh Chandra , Tervonen Henri , Karjalainen L. Pentti , Porter David A.
Published: March 2013

In this study, the constitutive flow behavior and static recrystallization characteristics of a Nb-microalloyed TWIP (Fe-20Mn-1.5Al-0.1Nb) steel under hot deformation conditions have been determined and results compared with those of Fe-25Mn-Al TWIP steels. Investigations using compression testing in a Gleeble simulator, including the double-hit technique, enabled the acquisition of flow stress and recrystallization data. These were analyzed to determine the powers of strain and strain rate as well as the activation energies of deformation and recrystallization (Qdef and Qrex). For given deformation and grain size parameters, the time for 50% recrystallization (t50) of the 0.1% Nb TWIP steel was significantly longer than for the Nb-free TWIP steel: it was comparable to that of Nb-microalloyed carbon steel. Qrex was higher than that of Type 304 stainless steel that has nevertheless much longer t50 times.
Recovery Kinetics in High Purity and Commercial Purity Aluminium Alloys
Authors: Bunkholt Sindre , Marthinsen Knut , Nes Erik
Published: March 2013

Motivated by improving current softening models for recycle friendly alloys, softening was investigated in high purity and commercial purity aluminium alloys. Utilizing the electron backscatter diffraction (EBSD) technique, orientation dependent sub-grain growth was characterized with respect to grain size and average boundary misorientation. In the high purity alloys, small additions of Mn in solid solution slowed down the recovery kinetics. The recovery mechanisms were however not altered, but recovery kinetics were found to be orientation dependent. The presence of high angle grain boundaries or transition bands, i.e. large and sharp orientation gradients, seemed to change the growth from slow and continuous to a faster and discontinuous process. This was typical for Cube and Goss, while weak, short and long range orientations gradients observed in Copper, S and Brass, did not alter growth which was slow and continuous. Before detailed studies of recovery of the commercial purity alloy were initiated, a rather slow recovery was observed and further investigated. Preliminary results indicate that iron in solid solution is dramatically slowing down the kinetics but can form clusters by an intermediate annealing in order to speed up recovery.
Evolution of Microstructure and Texture in Friction Stir Processed Al-Mg-Mn Alloy
Authors: Suresh K.S. , Kumar Nilesh , Mishra Rajiv S. , Suwas Satyam
Published: March 2013

Friction stir processing was carried out on the Al-Mg-Mn alloy to achieve ultrafine grained microstructure. The evolution of microstructure and micro-texture was studied in different regions of the deformed sample, namely nugget zone, thermo-mechanically affected zone (TMAZ) and base metal. The average grain sizes of the nugget zone, TMAZ and base metal are 1.5 μm ± 0.5 μm, 15 μm ± 8 μm, and 80μm ± 10 μm, respectively. The TMAZ exhibits excessive deformation banding structure and sub-grain formation. The orientation gradient within the sub-grain is dependent on grain size, orientation, and distance from nugget zone. The microstructure was partitioned based on the grain orientation spread and grain size values to separate the recrystallized fraction from the deformed region in order to understand the micromechanism of grain refinement. The texture of both deformed and recrystallized regions are qualitatively similar in nature. Microstructure and texture analysis suggest that the restoration processes are different in different regions of the processed sample. The transition region between nugget zone and TMAZ exhibits large elongated grains surrounded by fine equiaxed grains of different orientation which indicate the process of discontinuous dynamic recrystallization. Within the nugget zone, similar texture between deformed and recrystallized grain fraction suggests that the restoration mechanism is a continuous process.
Early Stages of Recrystallization in ECAP-Deformed AA1050 Alloy Investigated by SEM Orientation Mapping
Authors: Poplewska Jagoda , Paul Henryk , Berent Katarzyna
Published: March 2013

Early stages of recrystallization were observed for the technical purity aluminium alloy (AA1050). The samples were severely deformed by equal channel angular pressing and then annealed to obtain the state of partial recrystallization. The nucleation of new grains and the changes in ‘density’ of low- and high- angle boundaries were analysed using scanning electron microscopy equipped with high resolution EBSD system. After deformation in six passes along route A the alloy contained a structure of flat grains. On annealing, the structure coarsened and got transformed into nearly equiaxed grains by both discontinuous and continuous recrystallization. A particular role in the rise of nuclei and the structure spheroidization is attributed to migration of low-angle boundaries.
Recrystallisation of Magnesium Alloys Containing Rare-Earth Elements
Authors: Stanford Nicole
Published: March 2013

The static recrystallisation behaviour of two magnesium alloys after hot rolling have been examined. The alloys chosen for study were the conventional alloy AZ31, and an alloy containing the rare earth element Gadolinium. The recrystallisation kinetics were lower for the rare-earth alloy at low annealing temperatures, but at high annealing temperatures the kinetics were higher for the rare-earth alloy. It is suggested that this change in the comparative recrystallisation kinetics is a result of the improved mobility of the rare-earth solute at higher temperatures. This affects the recrystallisation kinetics through solute partitioning to the grain boundaries. The effect of this segregation on the recrystallisation texture is also discussed.
Observation of Growth Front on the Initial Stage of Goss Abnormally-Growing Grain in Fe-3%Si Steel
Authors: Ko Kyung Jun , Park Jong Tae , Han Chan Hee
Published: March 2013

During abnormal grain growth, a few Goss grains grow exclusively fast and consume the matrix grains. The Goss abnormally-growing grain (AGG) has peculiar features which are irregular grain boundaries and very high frequency of peninsular grains nearby the growth front of AGG and island grains trapped inside AGG. These features might provide a clue for clarifying the mechanism of Goss AGG. The experimentally-observed microstructural feature and grain boundary characterization of Goss were approached by the solid-state wetting mechanism. In this study, observing the three-dimensional wetting morphology in serial section images of Goss AGG by EBSD, we report some direct microstrucrual evidence supporting solid-state wetting mechanism for Goss AGG. The solid-state wetting mechanism for the evolution of the Goss AGG in Fe-3%Si steel explains the microstructural features evolved during secondary recrystallization, which cannot be approached by the conventional theories based on the grain boundary mobility.
Study of the Effect of Pinning Particles on Grain Size Distributions
Authors: Li Han , Lee Suk Bin , Rollett Anthony D.
Published: March 2013

The present paper studies grain growth in the presence of inert particles by performing large-scale simulations using a parallel Monte Carlo Potts model. The effect of the second phase particles on the grain size distribution (GSD) is analyzed. The GSDs diverge markedly from log-normal distribution for normal grain growth case. For the cases with low volume fraction of particles, we find that the grain size distributions approach log-normal as stagnation takes hold. For the cases with a high volume fraction of particles, however, medium-size grains reach the log-normal distribution but both lower and upper tails diverge noticeably from the log-normal distribution over time.
Three Dimensional Monte Carlo Simulations with Real Grain Orientations for the Role of Sub-Boundaries and Precipitates in Abnormal Grain Growth
Authors: Na Tae Wook , Park Chang Soo , Shim Hyung Seok , Lee Byeong Joo , Han Chan Hee , Hwang Nong Moon
Published: March 2013

Three-dimensional Monte Carlo simulations with real grain orientations are performed to study the role of precipitates and sub-boundaries in the abnormal grain growth. According to the simulation results, sub-boundaries in the abnormally growing grain and precipitates in the matrix grains are necessary for the abnormal grain growth. The simulation results can be best explained by the mechanism of sub-boundary enhanced solid state wetting. The simulated microstructure is very similar to that experimentally observed.
Grain Size Modeling during Hot Rolling of a Nb Microalloyed Steel Beam
Authors: Garcia Reis Emanuelle , Barbosa Ronaldo
Published: March 2013

Hot rolling of beams is carried out essentially in two stages. Roughing is performed in a reversing mill at temperatures in the range of 1100 oC, at relatively low strain rates and with long interpass times. Finishing is carried out in a reversing two stand mill at temperatures in between 1000 and as low as 700 oC considering parts of the web in the last passes. Strain rates are moderate and interpass times are in the range of 5 to 20s. There is, therefore, as it can be seen from the description just made of the rolling schedule, a fair resemblance to deformation in plate mills. Technology for themomechanical processing, TMP, of plates is very well known and disseminated. Application of this technology to beam rolling is, on the other hand, rather seldom known of. This paper addresses an application of TMP plate technology to beam rolling. In particular, austenite grain size evolution is examined. The usage of Nb microalloyed steels to this process is discussed in terms of possible beneficial effects to ferrite grain refinement.
Texture and Microstructure Evolution of a Zirconium Alloy During Uniaxial Compression at 500°C
Authors: Honniball Peter , Preuss Michael , Rugg David , da Fonseca Joao Quinta
Published: March 2013

The texture and microstructure evolution during uniaxial compression of Zircaloy-4 at 500C has been studied. X-ray diffraction was used to measure the bulk texture compressive after strains of 20% and 50%. Early stages of texture evolution involve the strengthening of the fibre through the action of prismatic slip. With further deformation, the basal poles move toward the rolling direction from the normal direction as a result of a non-prismatic slip system. A detailed EBSD study in a small region showed that the grains of the fibre are more stable than those of the fibre. The latter rotates further during deformation and shows a greater spread of grain average misorientation (GAM). This could be due to a greater accommodation of plastic strain in these grains and/or a difference in recovery rates between the two fibres.
Modeling Microstructure Development during Hot Working of an Austenitic Stainless Steel
Authors: Engberg Göran , Kero Ida , Yvell Karin
Published: March 2013

A number of physically based models are combined in order to predict microstructure development during hot deformation. The models treat average values for the generation and recovery of vacancies and dislocations, recrystallization and grain growth and the dissolution and precipitation of second phase particles. The models are applied to a number of laboratory experiments made on 304 austenitic stainless steel and the model parameters are adjusted from those used for low alloyed steel mainly in order to obtain the right kinetics for the influence of solute drag on climb of dislocations and on grain growth. The thermodynamic data are obtained using Thermo-Calc© to create solubility products for the possible secondary phases. One case of wire rolling has been analyzed mainly concerning the evolution of recrystallization and grain size. The time, temperature and strain history has been derived using process information. The models are shown to give a fair description of the microstructure development during hot working of the studied austenitic stainless steel.
3D Analysis of Microstructure Changes Occurring during Creep Tests of Ultra-Fine Grained Materials
Authors: Král Petr , Dluhoš Jiří , Peřina Pavel , Barták Tomáš
Published: March 2013

Experiments were conducted to determine microstructure changes occurring during thermal exposure in metals processed by equal-channel angular pressing (ECAP). The ECAP pressing was performed at room temperature by route Bc. Static annealing and constant load creep tests in tension were conducted at 0.3-0.5 Tm. The microstructure was examined by scanning electron microscope combined with focus ion beam - TESCAN LYRA 3 equipped with electron back scatter diffraction (EBSD). It was found that creep behaviour is influenced by synergetic effect of additional creep mechanisms like grain boundary sliding, more intensive diffusion processes or recrystallization.
Influence of Grain Size on Mechanical Properties of AZX311 Alloy
Authors: Sakai Naoto , Funami Kunio , Noda Masafumi , Mori Hisashi , Fujino Kenji
Published: March 2013

In the present study, the grain refinement, grain growth behavior, and tensile properties of rolled and annealed AZX311 Mg alloys were investigated. The yield strength and ultimate tensile strength of the rolled material were 360 MPa and 370 MPa, respectively, and the total elongation was 5%. When annealing was performed at 423 K for 1hr, the yield strength and ultimate tensile strength were unchanged, but the elongation increased to 10%. Furthermore, the strength and elongation did not change for annealing temperatures of 473–673 K owing to Al2Ca precipitations.
Solid Phase Growth of some Metal and Metal Oxide Thin Films on Sapphire and Quartz Glass Substrates
Authors: Sato Yuichi , Suzuki Toshifumi , Mogami Hiroyuki , Otake Fumito , Hatori Hirotoshi , Igarashi Suguru
Published: March 2013

Solid phase growth of thin films of copper (Cu), aluminum (Al) and zinc oxide (ZnO) on single crystalline sapphire and quartz glass substrates were tried by heat-treatments and their crystallization conditions were investigated. ZnO thin films relatively easily recrystallized even when they were deposited on the amorphous quartz glass substrate. On the other hand, Cu and Al thin films hardly recrystallized when they were deposited on the quartz glass substrate. The metal thin films could be recrystallized at only extremely narrow windows of the heat-treatment conditions when they were deposited on the single crystalline sapphire substrate. The window of the solid phase heteroepitaxial growth condition of the Al film was wider than that of the Cu film.
Orientation of Island and Small Grains in Grain Oriented Electrical Steels
Authors: Park Jong Tae , Ko Hyun Seok , Joo Hyung Don , Song Dae Hyun , Ko Kyung Jun , Park No Jin
Published: March 2013

Grain oriented electrical steels should have low core loss and high magnetic flux density. These properties are closely related with sharpness of {110} texture after secondary recrystallization. This Goss texture develops by abnormal grain growth during secondary recrystallization annealing. Based on experimental results, a general suggestion which estimates the magnetic properties after secondary recrystallization from a primary recrystallized texture can be made. For a material to have better magnetic properties after secondary recrystallization, its primary recrystallized texture should have not only larger number of ideal Goss grains, but also lower frequency of low angle grain boundary around those Goss grains.
Orientation Dependence of the Substructure Characteristics in a Ni-30%Fe Austenitic Alloy Deformed in Hot Torsion
Authors: Cizek Pavel , Beladi Hossein , Taylor Adam S. , Hodgson Peter
Published: March 2013

The present work examines the microstructure and texture evolution in a Ni-30wt.%Fe austenitic model alloy deformed in torsion at 1000 °C, with a particular emphasis on the orientation dependence of the substructure characteristics within the deformed original grains. Texture of these grains was principally consistent with that expected for simple shear and comprised the main A, B and C components. The deformation substructure within the main texture component grains was characterised by “organised” arrays of parallel microbands with systematically alternating misorientations, locally accompanied by micro-shear bands within the C grains. With increasing strain, the mean subgrain size gradually decreased and the mean misorientation angle concurrently increased towards the saturation. The stored deformation energy within the main texture component grains was principally consistent with the respective Taylor factor values. The microband boundaries corresponded to the expected single slip {111} plane for the A oriented grains while these boundaries for the C oriented grains represented a variety of planes even for a single grain.
Effect of Austenite Morphology on Ferrite Refinement in Microalloyed Steel
Authors: Dziedzic Dominik , Muszka Krzysztof , Majta Janusz , Palmiere Eric J.
Published: March 2013

The Strain-Induced Dynamic Transformation (SIDT) is an efficient way to overcome the limitation of grain refinement during the conventional thermomechanical controlled processing (TMCP) of steels. The present study deals with the effects of austenite morphology on the SIDT in microalloyed and IF steels. The discussion of the processing route in terms of chemical composition, deformation schedules, heating and cooling conditions is carried out by the means of torsion tests with deformation in metastable conditions. As it was expected, the microstructure of microalloyed steel was clearly controlled by the microalloying elements what, in turn, directly affectedthe SIDT products. Examination of water-quenched microstructures, just after deformation, revealed the morphology of "strain-induced ferrite". The kinetics of SIDT were observed and analyzed using the strain-stress curves. It is shown that presence of strain-induced precipitations in microalloyed steels accelerates kinetic of SIDT - by reducing the amount of Nb in solution. The changes in ferrite refinement of the experimental steels were explained from the view of the austenite morphology and processing parameters.
Evolution of Microstructure in Pure Nickel during Processing for Grain Boundary Engineering
Authors: Lin Brian , Rohrer Gregory S. , Rollett Anthony D. , Jin Yuan , Bozzolo Nathalie , Bernacki Marc
Published: March 2013

Grain boundary engineered (GBE) materials have improved properties that are associated with the high fraction special Σ3n boundaries in the microstructure, where n = 1,2,3. Previous experimental studies with high purity nickel before and after thermomechanical processing have shown that the fraction of Σ3 boundaries increased by at least factor of two [1]. Electron backscatter diffraction (EBSD) is used to characterize the evolution of these special boundaries throughout the recrystallization process of a 25% cold rolled sample annealed at 490°C. The fractions of the Σ3 boundaries and coherent twins have been measured over time revealing a steadily increasing behavior over the entire microstructure. However partitioning to only include recrystallized regions reveals a different behavior in the Σ3 boundaries as fractions, which increase rapidly at first and then stagnate over time. Additional triple junction characterization was performed to monitor the evolution of triple junctions containing special boundaries.
Precision Assessment of Surface Coating Roughness Height 3D Parameter St
Authors: Kumermanis Maris , Rudzitis Janis
Published: March 2013

One of the main surface coating quality indexes of details of mechatronic systems is surface roughness. And the surface roughness is described by surface roughness parameters. Nowadays characterization of surface roughness using three-dimension (3D) methods and parameters become more and more important. This type of surface quality characterization, unlike the two-dimension (2D) methods, provide a more complete view on the surface qualities, since the surface roughness is viewed as a spatial object. Within the last ten years intensive work is being carried out on the development of 3D roughness standards, therefore it is necessary to agree on a unified approach in the assessment of surface roughness 3D parameters. To make possible application of the ISO/DIS 25178 standard being developed one needs information on the determination of 3D surface roughness parameter precision, such as number of measurements, dimensions of measurement areas and their disposition on the measured surface.
Research on Tool Temperature Dependence on Lapping Grains Size
Authors: Molenda Justyna , Charchalis Adam , Barylski Adam
Published: March 2013

Commonly used as a finishing operation, lapping has been used for achieving ultra-high finishes and close tolerances between mating pieces. Its carried out by applying loose abrasive grains between work and lap surfaces, and causing a relative motion between them resulting in a finish of multi-directional lay. The grains activity (sliding and rolling) in the working gap causes not only the material removal but also the temperature rise of lap plate. This work presents the results of lapping plate temperature rise research. The investigation has been conducted to check the influence of grains size on. It was made during flat lapping with use of ABRALAP 380 lapping machine and infrared camera Thermo Gear G100. The lapping machine executory system consisted of three working conditioning rings. Plate temperature was measured during ceramic (Al2O3) elements lapping. The elements were valve sealing parts. After grinding they were processing with three abrasive grains sizes: F400/17, F800/6.5 and F1200/3. The abrasive mixture was boron carbide powder mixed with kerosene and machine oil with grain concentration 0.25. Other lapping parameters remained constant during process. The wheel speed was 60 rev/min and lapping pressure 0.04 MPa. In the next step the statistical analysis was conducted. It was analysed if the plate temperature is influenced by the grains size. A hypotheses testing method was use. Results were calculated for temperature rise values measured after 300 minutes of machine working. According to them the influence of abrasive grains size on plate temperature rise is statistically insignificant, what is not consisted with the model.
The Influence of Oil Ageing on the Change of Viscosity and Lubricity of Engine Oil
Authors: Sikora Grzegorz , Miszczak Andrzej
Published: March 2013

The report includes results of the study on the change of viscosity and lubricity of engine oil used in the two HEROS' harbour tug Caterpillar CAT3516DITA main engines, both with the similar amount of working hours. Each of the engines has a nominal power of 1421kW and usually works between 650 and 1800rpm. The examinated oil is a product of the Fuchs Oil Corporation, named Titan Truck Plus 1540, which meets the requirements of SAE 15W-40. The ageing of engine oil causes the change of its dynamic viscosity value. That change has effect on the process of lubrication and the wearing of slide journal bearings. The aim of this work is to evaluate the changes of viscosity and lubricity values of engine oil in the time of its exploitation. The changes of the viscosity and lubricity of engine oil were observed at specified intervals, between the oil changes. The results of the study are presented as the characteristics of viscosity and time in various temperatures and the shear rates. The measurements of the viscosity were made on the Haake Mars III rheometer, with the shear rates up to 200 1/sec and in the range of temperatures between-10°C to +120°C. This paper also includes information on the analysis of wear products, contaminants and additives in the investigated oil was made with the rotating disc electrode atomic emission spectrometer Spectro Incorporated Spectroil Q100. The Spectroil Q100 spectrometer can detect up to 22 different chemical elements that most often occur in the motor oil additives, contaminants and wear products. The lubricity of the examinated was measured on the T02-U four-ball tester.