bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Treatment Effects on Static and Dynamic Mechanical Properties of Sintered SINT D30 Powder Metal
Authors: Šori Marko , Verlak Tomaž , Glodež Srečko
Published: November 2013

Low cost, low material waste and good accuracy in components with complex geometry are the main reasons for powder metallurgy to be considered as a promising manufacturing process for the future. Like wrought steel, sintered steel can also be heat treated to increase surface hardness and to improve strength. This paper compares mechanical properties of the hardened sintered steel with the sintered steel of the same powder metal SINT D30. Firstly, the static strength of both samples is determined by quasi-static tensile tests. Results are compared in stress strain diagram and they show that the tensile strength of the hardened sintered steel SINT D30 can surpass 700 MPa. The main focus of this study is however fatigue behaviour of the sintered steel. Both sets of samples are tested on a pulsating test machine with the load ratio of R = 0. The first sample is subjected to a load that corresponds to 90 % of the yield strength and is then gradually lowered to achieve one million stress cycles without breakage. Obtained results are then presented as Wöhler curves and compared in S-N diagram.
Influence of the Composition of Cement Mortars Modified by Lime or Polymers on the Mechanical Properties and Microstructure of Mortars
Authors: Lenart Małgorzata
Published: November 2013

Cement – polymer composites are nowadays widely used in repair systems not only in case of concrete or reinforced concrete constructions but also in masonry. Polymers addition for example already at 5% m.c. modifies the structure of the cement – polymer composite in a way that many of the mechanical properties such as flexural strength, tensile strength or adhesion to substrates are improved. The paper presents the results of tests such as flexural, compressive or adhesion strength to ceramic substrate of hardened cement mortars with different composition, as well as selected cement mortars modified by two polymers: polyvinyl alcohol and styrene – butadiene polymer dosed at 5 % m.c. Four types of cement mortars modified by lime (component used in historical constructions as well as in contemporary masonry mortars) are also examined for comparison.
Influence of Fly Ash on Abrasion Resistance of Concretes with their Additions
Authors: Nowak-Michta Aneta
Published: November 2013

The influence of fly ash quality and quantity on abrasion resistance of hardened concretes with siliceous fly ash addition is analysed in the paper. Abrasion resistance was measured in two standard tests according to EN 1338: 2005: reference test of the Wide Wheel and alternative test of the Bohme. Cement was replaced with 20, 35, and 50% of Class F siliceous fly ash in three categories of losses of ignition A, B and C by mass. The water to binder ratio, the air-entraining and the workability of mixtures were maintained constant at 0.38, 4.5% and 150 mm respectively. Test results indicated that in both methods, all tested concretes according to EN 1338: 2005 could be classified to 4-the highest class of abrasion resistance. In reference test of the Wide Wheel fly ash quality and quantity not influences abrasion resistance. However, in alternative, Böhme test abrasion resistance lowering with growth quantity of fly ash in binder, while loss of ignition of fly ash no influenced abrasion resistance. There were no correlation between the abrasion resistance and the compressive strength.
Influence of Heat Treatment on Crack Tip Opening Displacement and on Resistance of Crack Propagation of Alloyed Steel
Authors: Pustaić Dragan , Cajner Franjo
Published: November 2013

The aim of the performed investigations was to determine the influence of two different heat treatment procedures, i.e. hardening and tempering vs. austempering, on some mechanical properties, as well as the influence of these procedures on the magnitude of some fracture mechanics parameters for example, crack tip opening displacement (CTOD) and J-integral. The experimental investigations were performed on the specimens made of spring steel 65Si7 (chemical composition: 0.69% C, 1.56% Si and 0.90% Mn).
Effect of Adding Graphite Powder to a UP Polymer on Friction and Wear for Different Loads and Rubbing Speeds
Authors: Larbi Said , Djebali Said , Bilek Ali
Published: November 2013

The aim of the present work is the investigation of the influence of graphite powder addition to an unsaturated polyester type polymer (32% styrene content in mass) on the mechanical and tribological properties. For this purpose, we conducted bending tests and wear tests with a combination of four loads and three speeds for three different compositions (0, 1 and 2% graphite). The wear tests are carried out on a dry type pin on disk tribometer. The disk is made of quenched and annealed C48 steel (540 Hv hardness). Before the rubbing process, the discs are subjected to polishing in order to obtain approximately the same initial surface roughness. The results show that the addition of graphite powder improves the tribological properties; a noticeable decrease of the coefficient of friction, the mass loss and the wear rate are achieved with the increase of the graphite powder percentage for all sliding speeds and loads. A 2% graphite content causes a drop of the friction coefficient from 0.4 to 0.2. The results of bending tests showed a significant decrease of the stress and strain at failure and a slight increase in Young's modulus. In addition, for the three compositions, the results show a clear preponderance of the influence of the load on the tribological properties.
Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range
Authors: Tofel Pavel , Škarvada Pavel , Sikula Josef , Cséfalvay Gabriel
Published: November 2013

Each material contains defects and in-homogeneities in a structure volume. It has influence on the properties of material (conductivity, mass density, mechanical properties). Interaction of the ultrasonic waves with defects or in-homogeneities in the solid state is not clear. Electro-ultrasonic spectroscopy can help to clarify this phenomenon. The electro-ultrasonic spectroscopy describes defects and un-homogeneities inside the sample structure. This method is quite different from electro-acoustic effect. Ultrasonic signal is in range from 20 kHz to 150 kHz. Ultrasonic signal changes geometry of the sample in elastic range only. The sizes of cracks are changing also in the sample volume. Conductivity near the area of cracks is strongly changing due to ultrasonic vibrations. It has influence on resistance of the sample which is changing along with a frequency of ultrasonic vibrations. The amplitude of the resistance change depends on the material, number of cracks, size of cracks and Eigen frequencies of the sample excited by ultrasonic wave. We applied the electro-ultrasonic spectroscopy on two types of varistors. It can be useful for understanding the relation between microstructure and mechanical properties of these types of varistors.
High-Temperature Elastic Properties of Ceramics in the System MgO-Al2O3-SiO2 Measured by Impulse Excitation
Authors: Gregorová Eva , Pabst Willi , Musilová Anna , Camerucci Maria Andrea , Sandoval María Laura , Talou Mariano Hernán
Published: November 2013

Youngs moduli of talc-based ceramics from the system MgO-Al2O3-SiO2 are measured for temperatures up to 1000 °C via impulse excitation. It is shown that, after pressing at 50 MPa and firing at 1280 °C, MgO-rich compositions exhibit higher porosity and lower Youngs moduli (approximately 2030 % lower than predicted via micromechanical relations). The Young moduli of materials with less MgO decrease with temperature, but those of MgO-rich ceramics increase with temperature and exhibit a large hysteresis between heating and cooling. Lower absolute values are mainly due to increased porosity, but the reason for the modulus increase with temperature and the hysteresis is the higher enstatite content in the MgO-rich compositions. For a special composition the Youngs moduli are more or less temperature-independent and without significant hysteresis effects, probably due to the low content of enstatite and the high content of sapphirine.
Microstructural Aspects of Low Cycle Fatigue of Aged GX12CrMoVNbN9-1 Cast Steel
Authors: Mroziński Stanisław , Golański Grzegorz , Werner Krzysztof
Published: November 2013

The paper presents the results of research on the changes in microstructure of GX12CrMoVNbN9-1 cast steel subject to aging at the temperature of 600°C and holding time of 8000 hours, followed by low-cycle fatigue. The characteristics of the microstructure of the examined cast steel after ageing and low-cycle fatigue was described using transmission electron microscopy (study of the dislocation microstructure) and morphology of precipitations. It has been shown that low cycle fatigue leads to the matrix softening as a result of the processes of recovery, polygonization and repolygonization. Moreover, the processes of precipitation of Laves phase and coagulation of M23C6 carbides were observed in the microstructure. Intensity of these processes depended not only on the temperature of fatigue tests, but also on the level of total strain amplitude εac.
Thermally Activated Dislocation Motion in an AS21 Alloy and Alloy Reinforced with Short Ceramic Fibres Studied at Elevated Temperatures
Authors: Zdražilová Zuzana , Trojanová Zuzanka , Máthis Kristián , Lukáč Pavel
Published: November 2013

AS21 magnesium alloy (2.1Al-1Si-balance Mg in wt.%) and the alloy reinforced with short δ-Al2O3 fibres (Saffil®) were deformed in compression at temperatures between 23 and 300 °C. Stress relaxation tests were performed in order to reveal features of the thermally activated dislocation motion. Internal and effective components of the applied stress have been estimated. The activation volume decreases with increasing effective stress. The values of the activation volume and the activation enthalpy indicate that the main thermally activated process in the alloy as well as in the composite is the dislocation motion in non-compact planes.
A Discrete Model for Diffusion-Induced Grain Boundary Deterioration
Authors: Jivkov Andrey P. , Yates John R.
Published: November 2013

Polycrystalline materials may suffer internal damage due to diffusion of chemically aggressive species during service. Diffusion rates are greatly enhanced on grain boundaries (GB). This can be modelled with discrete networks, where the GB structure is represented by links with local diffusivities. We present a site-bond model for concentration-driven diffusion that can be used to study the accumulation of chemical species at GB, leading to deterioration and eventual cracking. We employ realistic distributions of GB energies and corresponding diffusivities from published works. We show how the model can be used to predict macroscopic diffusivities with little experimentation. We demonstrate how the grain boundary structure controls the extent of internal damage resulting from the diffusion of chemical species.
Propagation of Fatigue Cracks in Notched Specimens of EN AW 7475-T761
Authors: Bär Jürgen , Wilhelm Gero
Published: November 2013

The influence of single overloads on the fatigue crack initiation and propagation of an EN AW 7475-T761 alloy was investigated using SEN-specimens. Into a base load with an amplitude of 80 MPa and an Rvalue of R=-1 tension compression overloads with an amplitude of 240 MPa have been introduced every 10,000 cycles. The crack length was measured with a DC-Potential drop method. The experiments have shown that cracks are initiated in the first 5% of the total lifetime and, therefore, the cyclic lifetime is dominantly determined by crack propagation. The investigation of the crack surfaces exhibit that a different number of individual cracks propagates within the specimens. The differences in the cyclic lifetimes indicate that the interaction between these cracks directly influences the cyclic lifetime. This shows that the differences in the crack propagation behaviour are responsible for the scatter of the determined cyclic lifetimes.
Magnesium AZ91 Alloy Cast Mechanical Properties Measured by the Miniaturized Disc-Bend Test
Authors: Romelczyk-Baishya Barbara , Brynk Tomasz , Molak Rafal M. , Jastrzębska Anna , Nowak Katarzyna , Pakiela Zbigniew
Published: November 2013

Miniaturized Disc-Bend Test (MDBT), also called the Small Punch Test (SPT) is used for characterizing the mechanical properties of metals, when only a small volume of material is available. This study was dedicated to investigating the mechanical properties of AZ91 magnesium cast alloy. The casts were prepared via gravity sand casting and have sections with different wall thickness. The examined samples were cut out of 30 mm and 10 mm thick walls. The correlation between results obtained from the tensile tests and MDBT was determined.
Modeling and Experimental Study of Long Term Creep Damage in Austenitic Stainless Steels
Authors: Cui Yi Ting , Sauzay Maxime
Published: November 2013

Austenitic Stainless Steels (SSs) are presently being investigated as appropriate candidates for structural components for the future Generation IV nuclear reactors. Austenitic SSs of different grades will operate at high temperature and suffer low stress loading for decades. At the laboratory, austenitic SSs have been subjected to creep tests at various stresses and temperatures between 500°C to 700°C, up to nearly 50·103h. Interrupted creep tests show an acceleration of the reduction in cross-section only during the last 15% of creep lifetime which may be called macroscopic necking. The modeling of necking using a modified Norton power-law allows lifetime predictions in agreement with experimental data up to a few thousand hours only. And the experimental results show that, the extrapolation of the 'stress lifetime curves obtained at high stress leads to large overestimations of lifetimes at low stress. After FEGSEM observations, these overestimates are mainly due to additional intergranular cavitation along grain boundaries. The modeling of cavity growth by vacancy diffusion along grain boundaries coupled with continuous nucleation proposed by Riedel has been carried out. Lifetimes for long term creep are rather correctly predicted with respect to experimental lifetimes. The lifetime curves predicted by either the necking model or the creep cavity one cross each other, defining transition times of five to ten thousand hours for temperatures between 600°C and 700°C, in agreement with experimental curves.
3D Discrete Dislocation Dynamics Applied to a Motion of Low-Angle Tilt Boundaries
Authors: Záležák Tomáš , Dlouhý Antonín
Published: November 2013

This paper presents a 3D discrete dislocation dynamics (DDD) model describing dislocation processes in crystals subjected to loadings at high temperatures. Smooth dislocations are approximated by short straight segments. Every segment is acted upon by a Peach-Koehler force obtained by summing up forces from all dislocation segments and a force due to the applied stress. The model addresses interactions between individual dislocations and rigid precipitates. The model is applied to a migration of low angle tilt boundaries (LATBs) characterized by different initial dislocation density and constrained by precipitates of different sizes. The calculations showed that, for applied shear stresses σxz lower than a certain threshold σcrit.(h), the LATB is inhibited by the precipitate field. For σxz above σcrit.(h), the LATB passes through the precipitate field. Some combinations of σxz and h lead to a decomposition of the LATB. The LATBs thus may evolve in three distinct modes depending on the initial microstructure. The threshold stress behaviour is known from creep tests of dispersion-strengthened NiCr alloys [1]. Furthermore, the critical stresses obtained from our calculations are below Orowan stresses for corresponding particle distribution. This behaviour has been also reported in creep experiments [1].
Optimization and Application of Process Parameters in an AZ61 Alloy Twin-Roll Strip Casting
Authors: Li Jin Tao , Xu Guang Ming , Yu Hai Liang , Su Li Hong , Deng Guan Yu , Lu Cheng , He Li Zi , Li Hui Jun
Published: November 2013

Twin-roll strip casting is a concerned technology for economically producing magnesium alloys sheets. In this paper, numerical simulation of the twin-roll strip casting of an AZ61 magnesium alloy was carried out and the optimal process parameters were obtained. Then, under the conditions obtained through simulation, AZ61 strips of good surface quality were successfully manufactured. The microstructure of the alloy by twin-rolled strip casting is obvious refined compared with that by conventional casting.
On the Influence of Mesh Size during Finite Element Simulation of Equal Channel Angular Pressing
Authors: Deng Guan Yu , Lu C. , Su Li Hong , Liu Mao , Wei Pei Tang , Li Jin Tao , Zhu Hong Tao , Liu Xianghua , Tieu A. Kiet
Published: November 2013

Equal channel angular pressing (ECAP) has attracted a lot of interest due to its ability for fabrication of bulk ultrafine-grained materials. With the development of computer skills, the computer-aided methods become very important and useful in understanding the deformation mechanism of ECAP. In this study, the influence of mesh size during finite element simulations of ECAP has been examined based on the plane strain condition assumption. Four different meshes have been compared and these results indicate that Mesh 600 and Mesh 2400 fail to capture the deformation features of ECAP accurately. Large corner gaps develop in these two cases and the simulated strains are smaller than the analytical calculations. Similar results have been obtained between Mesh 6369 and Mesh 12000 and the predicted features of plastic deformation and texture evolution are consistent with the experimental results.
Numerical Investigation of Knurled Shaft-Hub Connections and Especially of the Joining Process
Authors: Kleditzsch Stefan , Lätzer Michael , Awiszus Birgit , Leidich Erhard
Published: November 2013

Faced with increasing cost pressures, manufacturers need to find new solutions for shaft-hub connections. One example is the knurled interference fit, where a shaft with knurls and interference is pressed in a soft hub with a cylindrical bore. At present the potential of the knurled interference fit is not fully used, because there are no general standards available for the design and for the joining process. But the joining process in particular has an important impact on the join strength. A predominantly forming joining process offers some advantages compared to cutting. Forming allows a clearly higher contact pressure over the groove because of the displacement of the hub material, which leads to greater axial reliability. Also, the natural material structure is preserved by the forming, and this, in combination with the hardening of the hub, should allow a higher transmittable torque. The Finite Element Method is used for detailed investigation of the joining process and the transmission behavior in the axial direction. With this method, the local loads, for example the hardening of the hub over the groove due to the formed join, are investigated as well as further parameter variations (e.g., chamfer angle, interference). Hence, an analytical approach for the determination of the necessary joining force was derived.
Mechanical Properties of Tin Tailing Sand-Clay Mixture from Batu Gajah, Perak, Malaysia for Making Greensand Casting Mould
Authors: Abdullah Azhar , Sulaiman S. , Baharudin B.T.H.T. , Ariffin M.K.A. , Haliza N.
Published: November 2013

Tailing sand from ex-tin mine in Batu Gajah containing between 95.9 to 98.9% silica. In this research involved the process of, conducting the mechanical sieve grading to identify the size spread, plotting the grain size distribution and calculating the average grain size. Further on with the effects of controlled additions of clay (bentonite) and water and determining the working range on the mechanical properties. The investigation involved comparing the mechanical properties of the tailing sand to the requirement for foundry sand applications listed by Foseco Ferrous Foundrymans Handbook (Foseco). Permeability and green compression strength are the important mechanical properties and considered much in the sand casting mould preparation. These mechanical properties play a vital role in determining the allowable clay and moisture content for working range of tailing sand for making green sand casting mould. Experiments for this investigation were conducted according to American Foundrymen Society (AFS) standard of procedures. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various sandwater ratios bonded with 3.8%wt clay and then 7.4%wt clay, were compacted by applying three ramming blows of 6666 g each using Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using Ridsdale-Dietert universal sand strength machine and permeability number with Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured using moisture analyser. Tailing sand with allowable moisture content ranging from 3 to 3.5% (bonded with 3.8%wt clay) and 5.5 to 6% (bonded with 7.4%wt clay) were found to have optimum working range with effective green compression strength and permeability.
Influence of Filler Amount and Content on the Mechanical Performance of Joints Bonded with Metal Powder Filled Adhesive
Authors: Kavak Nergizhan , Altan Erhan
Published: November 2013

The objective of this study is to investigate the surface roughness that effect the capability of adhesive with adding aluminium powder and 63/37 Sn-Pb soft solder powder to the epoxy to increase the mechanical strength of joints. The adhesive strength of the joints was determined by utilizing the single-lap shear test. As seen from the experiments, the surface roughness has an important effect on the strength of adhesive bonded joints. Experimental results show that joints prepared by adhesive which was modified, adding in the amount of 5 wt% 63/37 Sn-Pb powder have more mechanical strength than joints compared to one which is prepared by adding aluminium powder with different ratios as 5, 25,50 wt%.
Evaluation of the Robustness of Surface Characterisation of Carbon Fibre Composites Using Wavelet Texture Analysis
Authors: Palmer Stuart , Hall Wayne
Published: November 2013

The mechanical properties of advanced composites are essential for their structural performance, but the surface finish on exterior composite panels is of critical importance for customer satisfaction. Previous work by the authors established the feasibility of wavelet texture analysis (WTA) for the task of automatically classifying the surface finish of carbon fibre reinforced polymer (CFRP) samples based on computer image processing. This paper presents an evaluation of the robustness of the WTA method to common process errors that can occur in the imaging of material samples. WTA creates a rich representation of the texture in an image that includes features related to both scale and orientation. Principal components analysis was used to reduce the dimensionality of the texture feature vector to a single principal component that could be used as the basis for discrimination between grades of CRFP sample surface finish quality. The results obtained indicate that the WTA method is robust to: significant horizontal and/or vertical translations of the sample being imaged; significant rotation of the sample being imaged; and significant dilation of the sample being imaged. The results obtained suggest that as long as reasonable precautions are taken in sample imaging, then the WTA method will yield repeatable results.
Performance of Solder Bond on Thermal Mismatch Stresses in Electronic Packaging Assembly
Authors: Sujan D. , Pang X.B. , Rahman M.E. , Reddy Moola Mohan
Published: November 2013

Thermo-mechanical stresses have been considered one of the major concerns in electronic Packaging assembly structural failure. The interfacial stresses are often caused by the thermal mismatch stresses induced by the coefficient of thermal expansion (CTE) difference between materials, typically during the high temperature change in the bonding process. This research work examined the effect of bond layer on thermal mismatch interfacial stresses in a bi-layered assembly. The paper verified the existing thermal mismatch solder bonded bi-layered analytical model using finite element method (FEM) simulation. The parametric studies were carried out on the effect of change of bond layer properties in order to provide useful references for interfacial stress evaluation and the electronic packaging assembly design. These parameters included CTE, temperature, thickness, and stiffness (compliant and stiff bond) of the bond layer. The recent development on lead free bonding material was being reviewed and found to have enormous potential and key role to address the future electronic packaging assembly reliability.
The Numerical Simulations for the Shot Peening Process
Authors: Liu Chun Ho , Wang A Cheng , Liang Kuo Zoo
Published: November 2013

To develop a generalized numerical model by the elasto-plastic formulation coupling with dynamic finite element method for the shot peening process of metal alloys is the main goal of this paper. The analysis code is based on the finite deformation theory; the optimum numerical technique and the relevant parameters of forming process. In this study, the simulations of single and multi shot forming process were performed. The effects of impact velocity and strain rate, size of workpiece, and the residual stress were observed and discussed in details. After comparing with the corresponding papers, the universal model for metal shot peening analyses will be developed completely. The most significant advantage of this paper is the development of the precise analysis technology to suit for the future necessity of the manufacturing processes. The suggested models and techniques are helpful in solving of impact problems or metal forming processes.
Development of a Composite Material from Agro Waste for Wear Resistance Application
Authors: Reddy Dareddy Ramana , Balunaik Banoth
Published: November 2013

The Friction lining is an essential part of braking system. Friction materials have their significant role for transmission in various machines. Their composition keeps on changing to keep pace with technological development and environmental requirements. Earlier asbestos has been used as a friction material because of its good physical and chemical properties. But later researchers eyed that there are many health hazards associated with asbestos handling. The average disk temperature and average stopping time for pass is increased and it has poor dimensional stability. Hence it has lost favor and several alternative materials are being replaced these days. In this work a non-asbestos bio-friction material is enlighten which is developed using an Agro-waste material palm kernel shell (PKS) along with other Ingredients. Among the agro-waste shells investigated the PKS exhibited more favorable properties. The developed friction material is used to produce automobile disk brake pads. The developed brake pads were tested for functional performance on a specially designed experimental test rig. Physical properties of this new material along with wear properties have been determined and reported in this paper. When compared with premium asbestos based commercial brake pad PKS pads were found to have performed satisfactorily in terms of amount of wear and stopping time.
Experimental Investigation on Surface Roughness and Tool Wear in Dry Machining of TiC Reinforced Aluminium LM6 Composite
Authors: Yusuf Muhammad , Ariffin M.K.A. , Ismail N. , Sulaiman S.
Published: November 2013

With increasing quantities of applications of Metal Matrix Composites (MMCs), the machinablity of these materials has become important for investigation. This paper presents an investigation of surface roughness and tool wear in dry machining of aluminium LM6-TiC composite using uncoated carbide tool. The experiments carried out consisted of different cutting models based on combination of cutting speed, feed rate and depth of cut as the parameters of cutting process. The cutting models designed based on the Design of Experiment Response Surface Methodology. The objective of this research is finding the optimum cutting parameters based on workpiece surface roughness and cutting tool wear. The results indicated that the optimum workpiece surface roughness was found at high cutting speed of 250 m min-1 with various feed rate within range of 0.05 to 0.2 mm rev-1, and depth of cut within range of 0.5 to 1.5 mm. Turning operation at high cutting speed of 250 m min-1 produced faster tool wear as compared to low cutting speed of 175 m min-1 and 100 m min-1. The wear minimum (VB = 42 μm ) was found at cutting speed of 100 m min-1, feet rate of 0.2 mm rev-1, and depth of cut of 1.0 mm until the length of cut reached 4050 mm. Based on the results of the workpiece surface roughness and the tool flank wear, recommended that turning of LM6 aluminium with 2 wt % TiC composite using uncoated carbide tool should be carried out at cutting speed higher than 175 m min-1 but at feed rate of less than 0.05 mm rev-1 and depth of cut less than 1.0 mm.
Elementary Research on Preparation of AlB12 Powder by Self-Propagating High-Temperature Synthesis (SHS)
Authors: Wang Chao , Ma Bao Ling , Zhang Lu , Cao Xiao Zhou , Yang He , Xue Xiang Xin
Published: November 2013

The preparation of AlB12 powder by SHS has been investigated. Mg, Al2O3 and B2O3 powders were mixed as staring materials. SHS products were treated by acid pickling. Adiabatic temperatures were calculated by HSC software. XRD, SEM, TEM analyses were used products after acid picking treatment. The reason caused AlB12 low purity is the formation of Mg0.4Al2.4O4 and insoluble matter
Surface Roughness Analysis of Magnesium Pieces Obtained by Intermittent Turning
Authors: Rubio Eva María , Villeta María , de Agustina Beatriz , Carou Diego
Published: November 2013

This paper presents an experimental study to analyze the surface roughness reached in pieces of UNS M11917 magnesium alloy obtained by intermittent turning. A design of experiments (DOE) was established to carry out the study. Namely, factors identified as posible sources of variation of the surface roughness and their levels, written between parentheses, are the following: depth of cut (1), feed rate (2), spindle speed (2), type of tool (2), quantity of lubrication (3), type of interruption (3), measurement length (3) and measurement generatrice (3). Due to the high number of possible combinations that can be generated with the set of factors and levels identified a combined design of experiments L4x32 was performed. Data are was analyzed by means of the analysis of variance (ANOVA) method. The main results of the statistical analysis highlight the great influence of the feed rate on surface roughness among the set of factors and their interactions considered. In addition, focusing on the intermittent cutting, type of interruption and its interaction with the type of tool used are also important sources of variation, but at a lower level than feed rate.
Mechanical Properties of Highly Filled Iron-ABS Composites in Injection Molding for FDM Wire Filament
Authors: Sa'ude Nasuha , Ibrahim Mustaffa , Ibrahim Mohd Halim Irwan
Published: November 2013

This paper presents the development of a new polymer matrix composite (PMC) material for use in injection molding machine. The material consists of iron powder filled in an acrylonitrile butadiene styrene (ABS) and surfactant powder material. In this study, the effect of iron powder was investigated as a filler material in polymer matrix composite and ABS was chosen as a matrix material. The detailed formulations of compounding ratio by volume percentage (vol. %) with various combinations of the new PMC are investigated experimentally. Based on the result obtained, it was found that, vol. % increment of iron filler effected on the hardness, tensile and flexural strength. With highly filled iron content in ABS composites increase the hardness and tensile strength of PMC material through an injection molding process.
Slurry Erosive Wear Behavior of Hot Extruded Al6061-Si3N4 Composite
Authors: Ramesh Chinnakurli Suryanarayana , Khan Saleem , Zulfiqar Khan , Sridhar K.S.
Published: November 2013

Silicon nitride possess excellent hot hardness and wear resistance coupled with very good corrosion resistance. Hence, in recent years, silicon nitride has been a serious contender as a reinforcement to develop light weight metal matrix composites for several technological applications. Al6061 is most popular matrix alloy as it possess excellent formability and in particular the quality of extrudates of Al6061 is quite high and are the most preferred in space and naval applications especially for support structures and torpedoes blades respectively. Improved corrosion and slurry erosion resistance on use of silicon nitride in nickel and aluminum alloy matrices have been reported by several researchers. In the light of the above, this paper focuses on development of Al6061-6wt% Si3N4 by stir casting the most economical and popular route followed by hot extrusion. Hot extrusion was carried out using 200T hydraulic press at extrusion ratio of 1:10 at a temperature of 550°C. Slurry erosion tests were carried out using 3.5% NaCl solution containing silica sand particles of size 312μm at different rotational speeds varying between 300 rpm and 1200 rpm. The sand concentration was varied from 10g/l to 40 g/l. Under identical test conditions, hot extruded Al6061-6wt% Si3N4 composite do possess better slurry erosion resistance when compared with matrix alloy. The mechanism involved in the material removal process during slurry erosion process will also be discussed.
Optimization of Glass Forming Ability of Al-Ni-Si Alloys by a Thermodynamic and Kinetic Approach
Authors: Cao Yi , Laws Kevin J. , Ferry Michael
Published: November 2013

This study reports the glass forming ability (GFA) of Al-Ni-Si alloys with selected compositions based on atomic packing efficiency and driving force criteria. Higher GFA was observed in the Al-rich lower liquidus temperature regions of the Al-Ni-Si system indicating that these compositions exhibit a lower driving force for crystallization. Five glassy alloys that were calculated to consist of densely packed atomic short-range ordering were found to retain an amorphous structure upon copper mould casting. The result of GFA in the Al-Ni-Si system provides a novel approach to develop new metallic glasses considering both the thermodynamic stability and sluggish crystallisation kinetics through efficient packing.
Influence of Element Types on Springback Prediction of Creep Age Forming of Aluminum Alloy Integral Panel
Authors: Zhan Li Hua , Xu Xiao Long , Huang Ming Hui
Published: November 2013

Creep Age Forming (CAF) is an effective forming technique combined forming and heat treatment, based on creep and age hardening characteristics of some aluminum alloys. It has been widely used to manufacture large integral panels with airfoil sections and complex curvatures of high strength aluminum alloy. The aim of this paper is to study the influence of element types on springback prediction of creep age forming of aluminum alloy integral panel. Firstly, the finite element models are built by 3D-solid elements and Shell elements separately. And then a set of creep aging constitutive equations of 7055 aluminum alloy are implemented into the commercial FE solver MSC.MARC through user defined subroutine. Finally, springback values predicted by 3D-solid elements model and Shell elements model respectively are compared under different height to width ratios. Some important conclusions were drawn. For the reinforcing panel with the height to width ratio is more than 5:1, shell elements should be used to get more accurate springback prediction result. If the height to width ratio is less than 5:1, solids elements should be used. Above conclusions provide theoretical basis for the study of CAF of the aluminum alloy integral panel by finite element simulation method.
Study on Functions of Chrome and Fluoride Ions in Plating Process of Tin Free Steel by Means of Cyclic Voltammetry
Authors: Li Jian Zhong , Wang Bo , Sun Xiu Li , Tian Yan Wen , Zhao Yue
Published: November 2013

Plating solution of tin free steel (TFS) presents strong corrosion and special chemical action properties of chrome ions and fluoride ions. Electrochemistry behavior of their ions in the plating process of TFS was investigated by means of cyclic voltammetry (CV). The results show that hydrogen and oxygen evolution peaks can only be found in CV curves of the carbon anode in fluoride solution. CV curves of the carbon anode in chromium trioxide solution consist of five anodic peaks and two cathodic peaks. When fluoride ions are added into chrome ions solution, anodic peak disappears at peak potential of 1.18V. For CV curves of lead alloy anode, anodic peak can be found at peak potential of-0.2V in fluoride solution, and oxidation process is in asymmetry with reductive process in chromium trioxide solution or the mixed solution. As to CV curves of lead oxide anode, the current density of all peaks in chrome ions solution is lower compared with that of carbon anode and lead alloy anode. When fluoride ions are added into chrome ions solution, the current density of the oxidation process obviously decreases, while the absolute value of reductive process increase remarkably
Yield Strength of Hot Forging Die Steels at Working Temperatures
Authors: Giskaas Shane , Wolfram Preston , Findley Kip O. , Levy Bernard S. , Van Tyne Chester J.
Published: November 2013

One mode that limits the usefulness of hot forging die steels is localized plastic deformation in regions of high pressure. To understand this behavior the yield strength of the steel needs to be measured at working temperatures in order to determine the likelihood of localized plasticity. One of the issues in using die steels for hot forging applications is that they are initially tempered to a hardness value when put into service. As the die is used to produce forged components, the contact with the hot forging causes the die to continue to temper and hence soften with continued used. To explore these issues three different die steels were obtained and tested experimentally. Experimental compressive yield strengths were determined for the three die steels (FX, 2714 and WF). The die steels were tempered to various hardness values prior to compression testing. The five room-temperature hardness values after tempering ranged from 20 to 38 HRC. The five temperatures for compression testing ranged from 593 to 704 °C (1100 to 1300 oF). From these tests a good characterization of the high temperature plastic behavior of each steel was obtained. It was found that the WF steel which had the highest alloy content was the strongest of the three steels under all test conditions. The FX and 2714, which had similar alloy contents (with FX having slightly less carbon, nickel and vanadium), had yield strengths that were close to each other at the intermediate temperatures, but at the high and low end of the testing range for temperature the FX was stronger than the 2714. Hence, to obtain the greatest resistance to localized plastic deformation during operations the choice of die steel should be WF, followed by FX and then 2714.
Laser Cladding of Stainless Steel Substrates with Stellite 6
Authors: Kusmoko Alain , Dunne D. , Li H. , Nolan D.
Published: November 2013

Stellite 6 coatings were produced using laser cladding of two different steel substrates (martensitic and austenitic stainless steels). The chemical composition and microstructure of these coatings were characterized by atomic absorption spectroscopy, optical microscopy and scanning electron microscopy. The microhardness of the coatings was measured and the wear mechanism of the coatings was examined using a pin-on-plate (reciprocating) wear testing machine. The results showed less cracking and pore development for Stellite 6 coatings applied to the martensitic stainless steel (SS) substrate. The wear test results showed that the weight loss for the coating on martensitic SS was significantly lower than for the austenitic SS substrate. It is concluded that the higher hardness of the coating on the martensitic SS, together with the harder and more rigid substrate increase the wear resistance of the Stellite 6 coating.
Dynamic Characteristics of Machine-Pile-Soil Vibration System with Interface Friction Coupling
Authors: Li Xiao Peng , Liang Ya Min , Zhao Guang Hui , Ju Xing , Yang Hao Tian , Wang Quan Bin
Published: November 2013

The efficiency of vibrating machines will be greatly improved with the proper working parameters. A new type of hydraulic vibration pile driver extractor is presented in this paper. The machine-pile-soil dynamic model of the hydraulic vibration pile driver extractor based on frictional forces and vibration coupling is established with frictional forces of the pile-soil contact surface and the resistance force of the pile-end. Furthermore, the nonlinear dynamical characteristics of the dynamic model are studied and the influences of different system working parameters on frictional forces of pile-soil interface, working efficiency and capability are discussed by numerical simulation. The different working parameters are exciting force, frequency and stiffness. The results show that the suitable parameters of the vibrating machine can change the soil characteristics and decrease the frictional forces of the pile-soil interface. The work can provide useful guidance for the research on the vibration friction, selection in the suitable parameters of interface surface in engineering and design in the development of such machines.
Tribological Performance of Aqueous Copolymers Solutions in Metallic Contact
Authors: Novareza Oyong , Kosasih Bu Yung , Tieu K. , Zhu Hong Tao
Published: November 2013

Tribology performances (friction and anti-wear) of aqueous symmetrical tri-block normal and reverse copolymer solutions have been investigated. The ball-on-disk experiment was carried out to measure the coefficient of friction of solutions used at ~25°C and ~50°C. The interaction of alkyl phosphate ester, an anionic surfactant, and the aqueous copolymer solutions was also investigated. When solution was supplied at ~50°C, high friction and severe wear were found indicated that the solutions were not able to protect the surface. The friction and the anti-wear was found to improve when solution used at ~25°C. However, adding alkyl phosphate ester as extreme pressure additive into aqueous solutions produced a stronger adsorbed lubricant film protecting the surface. Low COFs were obtained from solutions below and above the cloud point. For the wear volume, the presence of phosphate ester produced comparable wear with the solution without added alkyl phosphate ester. The stainless steel was found less reactive to the alkyl phosphate ester hence the wear not much reduced. The possible lubrication mechanism is discussed by analysing the worn tracks using Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM) and the water contact angle measurements.
Influence of Vibration Time and Frequency on Surface Finishing Using Vibration-Assisted Micro-Forging
Authors: Bai Yang , Yang Ming
Published: November 2013

Vibration-assisted micro-forging was proposed for metal foil surface finishing. The mechanism was investigated by analysis of strain, surface roughness, microhardness, real / nominal contact area ratio and forming work at different vibration time and frequencies. Results show that vibration time and frequency influence the surface deformation by means of real contact area and forming work accordingly.
Effects of Induction Heat Treatment on Austenitic Transformation, Microstructure and Mechanical Properties of Pipeline Steels
Authors: Xiao Fu Ren , Han Xiu Lin , Liu Yan Mei , Lu Guang Ping , Liao Bo
Published: November 2013

The effects of heating rate, heating temperature and cooling rate on the microstructures and mechanical properties of four pipeline steels for high frequency electric resistance welded pipe have been studied by using a Gleeble-3500 thermo-mechanical simulator. The results show that the heating rates have an effect on austenizing phase transformation temperature (Ac1 and Ac3). It shows that there is a linear relationship between heating rate and austennizing temperature (Ac1 and Ac3) in the range of tested heating rate. With the heating temperature increasing, the strength property goes up, on the contrary, the strength begins to go down when the heating temperature exceeds 900 °C, then a lowest strength point appears on 925 °C in the testing scope. As the further increase of the heating temperature, the strength goes up again. Moreover, the cooling rate has a great effect on the microstructure and the mechanical properties. With the decrease of cooling rate, the strength decrease significantly, meanwhile, the microstructure becomes coarse, even the banded structure can be found. As the conclusion, the optimum heating temperature is 950 °C, and cooling rate is from 8.5 to 13 °C/s.
A Smart System to Determine and Control for the Process Parameters in Pipeline Welding
Authors: Jeong Young Jae , Kim Hak Hyoung , Chand Reenal Ritesh , Na Hyun Ho , Lee Ji Hye , Kim Ill Soo
Published: November 2013

Determination of the optimal welding parameters to achieve specific weldments on a new material is usually an expensive and time consuming. To determine the welding parameters using Artificial Intelligence (AI) technologies, one must consider many factors including productivity, thermal input, defect formation, and process robustness. Determination of the welding parameters for pipeline welding is based on a skilled welders long-term experience rather than on a theoretical and analytical technique. In this paper, a smart system develops which determines welding parameters and position for each weld pass in pipeline welding based on one database and FEM model, two BP neural network models and a C-NN model. The preliminary test of the system has indicated that the system could determine the welding parameters for pipeline welding quickly, from which good weldments can be produced without experienced welding personnel. Experiments using the predicted welding parameters from the developed system proved the feasibility of interface standards and intelligent control technology to increase productivity, improve quality, and reduce the cost of system integration.