bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation on Earing Behavior of AA 2024-T4 and AA 5754-O Aluminum Alloys
Authors: Turkoz Mevlut , Dilmec Murat , Halkaci Huseyin Selcuk
Published: July 2011

Deep drawn parts usually have different wall heights because of earing behavior. This behavior is due to the planar anisotropy (Δr) of sheet metals. A measure of the variation of normal anisotropy with the angel to the rolling direction in sheet plane is known as planar anisotropy. If the magnitude of the planar anisotropy is relatively large as absolute value, the earing behavior becomes more effective so larger ears occur. Furthermore, the orientation of the sheet with respect to the die or the part to be formed will be important. In addition, cutting of scraps in the parts which have ears leads to material waste. The scope of this study is to determine the planar anisotropy of AA 5754-O and AA 2024-T4 aluminum alloys and to investigate the earing behavior by the way of deep drawing of cylindrical cups.
Influence of Electrode Profiles on Electrical Discharge Machining of Titanium
Authors: Zain Zakaria Mohd , Khan Ahsan Ali , Abdulkareem Suleiman
Published: July 2011

Electric discharge machining (EDM) is an effective manufacturing technique that enables the production of parts made of hard materials with complicated geometry that are difficult to produce by conventional machining processes. EDM is a process of eroding material by transient action of electric sparks on electrically conductive materials, one being the workpiece the other being the electrode immersed in a dielectric fluid and separated by a spark gap. The EDM ability to control the process parameters to achieve the required dimensional accuracy and surface finish has placed this machining operation in a prominent position in industrial applications. This work reports on the different electrode profiles on the machinability factors of surface roughness (Ra) and material removal rate (MRR). The machining factors used in this study are the current (I), on-time and off-time. Based on the experimental results influence of the electrode profile on the responses were made and reported in this study.
A Programmable System for Treatment of Alloy Steels at Cryogenic Temperatures
Authors: Farhani F. , Niaki Keyvan Seyedi
Published: July 2011

Treatment of alloy steels at cryogenic temperatures increases their wear resistance, which is an important consideration in industrial applications. The treatment of metal samples is performed in a dedicated cryogenic processor, with provisions for precise time/temperature control of the samples on the basis of pre-defined temperature protocols. There is little information on the design and construction of cryogenic processors in the open literature. In this paper, development of a simple and inexpensive programmable processor for treatment of metals at cryogenic temperatures has been presented. Considerations for the selection of suitable cooling method and reduction of liquid nitrogen consumption have been discussed. To demonstrate the usefulness of this processor, a metal sample has been cryotreated. Results of the treatment show a more uniform microstructure and less retained austenite in the treated metal sample, which is due to the transformation of most of austenite into the harder martensite phase. Overall results show that the design methodology presented in this paper can be adopted by other researchers for constructing similar processors for studying the effect of cryogenic temperatures on enhancement of wear resistance and other mechanical properties in metals.
The Effect of Scan Speed on Engraving Depth and Surface Roughness of AISI H13 Tool Steel
Authors: Kasman Şefika , Saklakoğlu İ.E.
Published: July 2011

The aim of this study is to investigate the effect of scan speed and frequency on surface roughness and engraving depth of AISI H13 hot work tool steel. The experimental studies were conducted by fiber laser marker machine. The relationship between the parameters is showed that the highest surface roughness and depth values were achieved at lowest scan speed (125mm/s). The depth and surface roughness of engraved geometry was decreased at increase in scan speed. It was concluded that, the surface roughness and depth can be controlled by scan speed and frequency.
Experimental Investigation on Fiber Laser Cutting of Ti6Al4V Thin Sheet
Authors: Scintilla Leonardo Daniele , Sorgente Donato , Tricarico Luigi
Published: July 2011

The high strength to weight ratio and good corrosion resistance of titanium alloys, have led to an increasing use of these materials, particularly in the aerospace industry. The laser cutting technique may be a promising tool in machining titanium alloy parts like those with subsequent welding requirement: in this case, surface quality of the kerf edges is of great importance. The low thermal conductivity and the high chemical activity of titanium alloys lead, in fact, to alterations of the surface properties of the machined zone. This paper presents the results of titanium alloy laser cutting using a 2 kW fiber laser. The cutting process was performed in continuous wave mode and using Argon as shear gas. Laser cuts were realized on titanium alloy Ti6Al4V sheets 1mm thick. Image analysis and microscopy, were carried out to examine the cutting edge quality features including thickness of the recast layer and heat-affected zone.
Rheological Characterization of Water Atomised Stainless Steel SS316L for Micro MIM
Authors: Ibrahim Mohd Halim Irwan , Muhamad Norhamidi , Sulong Abu Bakar
Published: July 2011

This paper investigates the performance of feedstock characteristics for micro metal injection molding (μMIM) by using optimum power loading variation and rheological characterization. The study has been emphasized on the powder and binder system in which stainless steel SS316L powder are mixed with composite binder, which consists of PEG (Polyethelena Glycol), PMMA (Polymethyl Methacrilate) and SA (Stearic Acid) by variation of powder loading concentration. The rheology properties are investigated using Shimadzu Flowtester CFT-500D capillary rheometer. As the geometry of water atomised stainless steel powder are irregular shape, therefore it is expected significant changes in the rheological results that can influence the microcomponent, surface quality, shape retention and resolution capabilities. The optimization of the μMIM rheological properties as a function of stainless steel powder loading concentration are evaluated by flow behavior exponent, activation energy and moldability index. From the results, it shows that 61.5%vol contributes a significant stability over a range of temperature and the best powder loading from a critical powder volume percentage (CPVP) and rheological point of view.
Effects of Post Weld Ageing Heat Treatments on the Microstructure of 17-4PH GTA Welded Joints
Authors: Akbari Mousavi Seyed Ali Asghar , Hosein Abad S.A. Hoseini
Published: July 2011

The mechanical and metallurgical properties of the 630 (17-4PH) precipitation hardening stainless steel is greatly influenced by the type of applied heat treatments cycles. In order to achieve the homogenous microstructure in the weld metal and eliminate the HAZ due to producing the weak mechanical strength, and producing similar microstructures and mechanical strength in both weld and base metal, the study was conducted to find an optimum pre and post heat treatments before and after welding. The 2.2mm thick and 48mm tube diameter made of 630 stainless steel were welded under various operational parameters. The samples were subjected to pre weld solution treatment and post weld aging heat treatment. To reveal the microstructures of the welds, the optical and scanning electron microscopy of the welds carried out. The study shows that the direct ageing treatment at 6200C after welding can give rise to the best heat treatment to produce, the uniformity in the grain size, mechanical strength and hardness, between the base metal and the weld metal.
Etching Rate of Machinable Glass Ceramic
Authors: Ting Huey Tze , Abou-El-Hossein Khaled A. , Chua Han Bing
Published: July 2011

Micromachining of advanced ceramics has been growing tremendously especially in the MEMs industry. All the time, researchers and industrial engineers have strived to achieve the lowest production cost at possible highest quality in micromachining operations. In this paper, the micromachining operation by means of chemical etching of ceramics is discussed. Machinable glass-ceramic (MGC) is used as the substrate and the influence of various input factors of the etching process is analyzed. These factors include etching temperature, etching period and, etching solution. The etching rate is then analyzed by calculating the weight loss per minutes. In order to establish the relationship between these factors, central composite design (CCD) and artificial neural network are used. Additionally, a prediction model that can be used with a high level of confidence in the industry is created at the end of the analysis.
Experimental Investigation into Pulsed Nd:YAG Laser Micro-Turning of Engineering Ceramics
Authors: Kibria G. , Sharma B. , Doloi B. , Bhattacharyya B.
Published: July 2011

Laser beam machining (LBM) is the most exciting thermal energy based non-contact type advanced material machining method to process almost whole range of materials. The laser microturning of ceramics are highly demanded in the present industries because of its wide and potential uses in various engineering fields such as automobile, electronics, aerospace, biomedical applications etc. The present paper addresses the basic experimental study of Nd:YAG laser microturning of advanced engineering cylindrical shaped ceramic material to explore the desired laser output responses i.e. depth of cut and surface roughness by varying laser micro-turning process parameters such as lamp current, pulse frequency and rotational speed of workpiece etc.
Effect of Electron Beam Bombarding of the Catalyst Layer on the Growth of Carbon Nanostructures by TCVD Method
Authors: Mahmoodi A. , Ghoranneviss M. , Hanifeh D. , Mehrani K. , Rahbar Zareh M.
Published: July 2011

The growth behavior of carbon nanotubes (CNTs) grown on electron bombarded catalyst layer has been investigated in this paper. A hot cathodic electron beam facility was employed to electron bombarding of catalyst layer before stage of CNTs growth. The growth of carbon nanotubes was performed on the Fe catalyst layer with sio2 substrate in an environment of different mixed gases (H2, NH3 and C2H2) by Thermal Chemical Vapor Deposition (TCVD) system. The pretreated substrates were probed by Atomic Force Microscopy (AFM) and CNTs grown was confirmed by Raman spectroscopy. Moreover, all samples were analyzed by Scanning Electron Microscopy (SEM) before and after growth of CNTs. SEM analyzes clarified that the catalyst grains has been smaller under effect of electron beam bombardment.
The Effect of Microstructure on the Photocatalytic Properties of TiO2
Authors: Khameneh Asl Shahab , Kianpour Rad M. , Sadrnezhaad Sayed Khatiboleslam , Vaezi Mohammad Reza
Published: July 2011

Titanium dioxide is a cheap, chemically stable and non-toxic material. However its photocatalytic properties are unstable and it is a modest semiconductor and a mediocre insulator. For several applications it would be interesting to make it either more insulating or more conducting. The goal of this work was to modify the photocatalytic properties of nano-crystalline TiO2 powders by wet chemical routes and hydrothermal methods to understand the mechanism leading to these modifications The principal factors that influence the photocatalytic properties are on the one hand the concentration and nature of the chemical and physical conditions in TiO2, and on the other hand the morphology of the powders. The study was split into two parts. The fist part describes the modifications of the material obtained by chemical preparation's parameters. Like: preparation method, pH., additives, surfactants, and temperature. The second part describes the modifications obtained by modifying the photo catalysis reactors. Several analysis techniques have been used to characterize the TiO2 samples. They are essentially divided in four categories. The chemical analyses included electron probe microanalyses. The structure and morphology analyses of powders were carried out with x-ray diffraction. The photo catalytically properties in batch or CRS mode were measured in room temperature. Finally optical transmission provided information on the electronic states and morphology of the samples. The results imply that powders with anatase 40% and rutile 60 % with 15nm crystallite size have the optimum properties.
A Process Investigation for Micro-EDM Fabrication of through Holes in Thin Copper Sheets
Authors: Tam H.Y. , Jiang W. , Chan K.L.
Published: July 2011

This paper reports a study of a micro-EDM process to fabricate micro-through holes in 30 micron thick copper sheets. Circular holes in various micro-sizes were produced by a micro-EDM machine and with tungsten electrodes. Scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDX) were used to identify the influence of electric sparks on the quality of the fabricated features by careful study of resulted cavitation, adhesion of debris, and re-solidification of molten materials, etc. Such analyses allow the generalization of the relevant fabrication mechanisms. In addition, measurements of overcut of the holes facilitate a working model to be developed for predicting the overcut as a function of process parameters including the discharge capacitance and the working voltage of the circuitry. Results of this study enable the derivation of proper settings for fabricating holes of good quality and permit the precision fabrication of the range of micro-throughholes.
Tribological Study of TiN Nano Structured Films Deposited on Plasma Nitrided H11 Steel by Pulsed DC PACVD
Authors: Raoufi M. , Mirdamadi S. , Mahboubi Farzad , Ahangarani S. , Mahdipoor M.S. , Elmkhah H.
Published: July 2011

In recent years, plasma-assisted chemical vapor deposition (PACVD) has been introduced as a suitable technique to deposit hard coatings on to tools of complex geometries. This study focuses on the influence of process parameters during plasma nitriding and TiN coatings, such as duty cycle, treatment time and temperature parameters on the properties of nanostructured binary layers. To improve performance and the quality of the samples, a duplex process combining a plasma nitriding (PN) pre-treatment and a plasma-assisted chemical vapour deposition (PACVD) was applied on the steel surface. A mixture of H2, N2, Ar and TiCl4 was used to deposit a thin film of TiN on H11 steel. The microstructural, mechanical and tribological properties of the coating were investigated using X-Ray diffraction, scanning electron microscopy, atomic force microscopy combined with nanoindentation and pin-on-disc measurements. The results indicate that the small grain size was obtained at low duty cycle (33%) and increased with increasing of the duty cycle to 60 %. Calculated roughness of surface for duty cycle 50 % was 72 nm.
Formation of TiN Dispersed Composite Layer on Steel Surfaces by Titanium Powder Preplacement and TIG Surface Melting Processes
Authors: Mridha S. , Dyuti S.
Published: July 2011

The possibility of forming a TiN dispersed composite layer on steel was studied by preplacement of titanium powder on steel surface and melting under TIG (Tungsten inert gas) torch in a reactive environment. The surface melting of preplaced 1.8 mg/mm2 Ti powder was performed under TIG torch with energy inputs of 324,378 and 432 J/mm in a pure nitrogen environment. With these melting conditions, the powder layer along with a thin layer of the substrate melted and produced a melt pool of around 1mm thickness. The resolidified melt layer consisted of dispersion of TiN dendrites in ferrite matrix and thus a composite of TiN in ferrite is created on the steel surface. The concentration of dendrite population was found to be higher nearer the melt surface compared to the deeper depth. A maximum surface hardness of about 2000 Hv was developed at the surface when glazed with an energy input of 432 J/mm and the hardness decreased gradually away from the surface. The hardness development is directly related to the concentration of TiN dendrites.
Formation of Ti-Al-N Dispersed Layer on Steel Surface by TIG Melting in a Reactive Environment
Authors: Dyuti S. , Mridha S. , Shaha S.K.
Published: July 2011

In this study an attempt has been made to produce titanium-aluminium dispersed hard nitride layer on mild steel surfaces by preplacement of 50 % Ti and 50 % Al powder mixture and then melting with TIG torch under nitrogen environment. Parameter such as heat input of the torch was varied between 540, 608 and 675 J/mm and its effect on the resolidified melt pool was studied. Glazing under all energy inputs produced more than 1mm thick resolidified clad layer. The microstructural analysis revealed the clad layer with dispersion of dendrites of Ti-Al nitrides and Ti- Al intermetallic in ferrite matrix. The concentration of dendrites were found to be maximum near the surface and decreased at deeper depths.The maximum hardness of the modified surface layer was found to be 900 Hv compared to180 Hv of the mild steel substrate.
Tribological Characteristics of CVD Nanocrystalline Diamond Film Grown by Bias Enhanced Nucleation Process
Authors: Askari Syed Jawid
Published: July 2011

Nanocrystalline diamond (NCD) films on titanium alloys are of importance for tribology and biomedical implants. However, due to the different thermal expansion coefficients of the two materials, the complex nature of the interlayer formed during diamond deposition, and the difficulty in achieving high nucleation density, it is difficult to deposit adherent NCD films on titanium and its alloys. The aim of this research work is to successfully produce smooth, low roughness and well adherent NCD film on a pure Ti substrate by bias enhanced nucleation (BEN) process using microwave plasma chemical vapor deposition (MWPCVD) method. The friction coefficient was estimated to be around 0.06 in dry air using ball on disk tribometer with reciprocating sliding against a cemented carbide ball of 10 mm diameter at a high contact load of 20 N in dry air. The friction coefficient of bare Ti was between 0.55-06.
Study on the Effect of Nano and Micro MoS2 Powder in Micro-Electrical Discharge Machining
Authors: Prihandana Gunawan Setia , Sriani Tutik , Prihandana Kei , Prihandana Yuta , Mahardika Muslim , Bin Abdul Shukor Mohd Hamdi , Mitsui Kimiyuki
Published: July 2011

The application of powder mixed dielectric to improve the efficiency of electrical discharge machining (EDM) has been acknowledged extensively. However, the study of micro-size powder suspension in micro-EDM field is still limited. In this research, nano and micro size powder of MoS2 were used as catalyst agent. Powder suspension in different size was able to provide significant improvement in material removal rate and surface quality to increase the efficiency in μ- EDM processes.
The Effect of Black Powder Composition on the Erosion of Compressor's Impeller in Gas Transmission Line
Authors: Saremi M. , Kazemi M.
Published: July 2011

Black powders coming from the interactions of pipe and other metals with the environment in gas transmission line can cause severe problems in the industry. In this work the composition of the collected black powder from up stream of the filtering system analyzed using XRF and XRD techniques. Erosion test is carried on the samples of impeller alloy in the black powder alcoholic slurry in a laboratory set up. It is shown that the main constituent of the black powder is magnetite. The rotation speed and presence of humidity can enhance the erosion/corrosion with the consequence of more black powder production.
Dynamic Model of Compaction Process of Metallic Powders
Authors: Mohammadi K. , Darvizeh Abolfazl
Published: July 2011

Dynamic modeling of compaction process ,and evaluation of hardening parameters of powder compacts undergoing uni-axial/multi compaction is a tedious process and requires many elaborate tests .However ,assuming a two-parameter failure surface ( such as Mohr–Coulomb),evolution of failure surface may be monitored by two points on the failure surface. Results of uni-axial compression and direct or indirect tensile tests may readily provide the two required points. In order to assess this hypothesis ,a laboratory investigation was carried out using atomized iron powder(WPL-200) and aluminum powder(+160Mm) . Green compacts of the said drop-hammer , specifically designed for this purpose. Specimens with various relative compactions were produced and tested in uni-axial compression test and Brazilian split test .Variations of compressive/tensile strength with compaction energy(hammer speed) and relative density were studied and hardening law for green compacts were developed.
Finite Element Simulation of Nosing of Tubular Circular Metallic Tubes Using Parallel Computing
Authors: Khapre R.N. , Gupta P.K.
Published: July 2011

The paper presents an implementation of parallel computing technique in Finite Element Method to simulate the nosing of circular tubes. An earlier developed code FEMLD has been updated to simulate the nosing process of circular tubes. The code was originally developed to simulate the axial and lateral compression of metallic tubes of various shapes [8] on platform of supercomputer PARAM 10000. A parametric study has been carried out on tube specimens and the obtained results are presented. On the basis of the obtained results, the mechanics of the nosing process is presented and discussed. Various components of computational time has been obtained and presented to evaluate the performance of developed code for parallel computing. The time variation and speedup with number of processors is also discussed.
Determination of Arsenic (III) and Arsenic (V) Species by Preconcentration and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in Drinking Water Samples Analysis
Authors: Rahman M.M. , Mohd Yusof Alias , Wood A.K.H. , Shamsiah A.
Published: July 2011

A simple and less expensive solvent extraction method was used with inductively coupled plasma mass spectrometry (ICP-MS) in the speciation of two environmentally significant, toxic forms of arsenic: arsenite and arsenate. Dissolved inorganic arsenic species in drinking waters from reservoirs and treatment plants were determined by the inductively coupled plasma mass spectrometry analyses. Prior to the analysis the water samples were precocentrated by solvent extraction using APCDT to separate the arsenic species from elemental interferences. The detection limit of this method achieved was 0.059 gL-1. The suitability of the technique in this work is discussed in relation to risk assessment studies of public health.
A Fundamental Study of Vibration Assisted Machining
Authors: Abdur-Rasheed Alao
Published: July 2011

Conventional diamond cutting of ferrous materials is rarely economical due to the rapid tool wears which result from diffusion and graphitization of the tools. Conventional machining of hard-brittle materials like silicon and germanium results in surface and subsurface damage due to their brittle fracture. Although ductile mode machining (DMM) concept can be used to have a flawless machining on these materials but the mirror surfaces can only be realized on expensive ultraprecision machine tools because the critical depth of cut must be on the order of 1μm or less. Furthermore, there is a need to eliminate or reduce the use of cutting fluids during machining due to their attendant ecological hazards. However, grinding is one of the most difficult processes with regard to eliminating cutting fluids. Vibration assisted machining (VAM) can be used to minimize the problems enumerated above. VAM combines precision machining with small-amplitude tool vibration to improve the fabrication process. It has been applied to a number of processes ranging from turning, drilling to grinding. Therefore, this paper discusses DMM, the general overview of VAM, the basic kinematics of one-dimensional VAM; the advantages derived from using VAM and the ability of VAM to machine brittle materials in the ductile regime at increased depth of cut are described. Finally, the research directions in VAM are outlined.
Thermodynamic and Kinetic Modelling Hydrogenation of Titanium Particles and Sheets
Authors: Li Wei Qi , Zhou Jin , Gao Wei Min
Published: July 2011

Use of hydrogen as a temporary alloying element in Ti alloys is an attractive approach to improve the mechanical properties of the materials, enhance processability and thereby reduce manufacturing costs. In this paper, the hydrogen diffusion process and the phase transformation both between Ti particles and in Ti sheets were simulated to analyze the mechanism of hydrogen diffusion in different phases (α-Ti, β-Ti and TiHx). With the simulation based on the kinetics and thermodynamics, quantitative behaviors of the hydrogen diffusion and the phase transformation were analyzed. The simulation results provide an insight into the diffusion process and improve the fundamental understanding of the mechanism of diffusion and phase transformation.
A Study on Cooling Characteristics of Thermoelectric Cooling System Using Thermoelectric Materials
Authors: Yang Ho Dong , Yoon Hee Sung , Oh Yool Kwon
Published: July 2011

This study investigated on cooling characteristics of thermoelectric cooling system using thermoelectric materials as Bi-Te alloy. The thermoelectric module used as thermoelectric materials of thermoelectric cooling system can achieve heating and cooling by change of electricity direction. When thermoelectric module and cooling fan received 12V from DC power source, the cooling region was occurred in thermoelectric cooling system. Also, the piezoelectric actuator was applied to improve the cooling effect and investigate the heat transfer phenomenon. The temperature distribution of cooling region was measured to investigate cooling characteristics of thermoelectric cooling system. The flow phenomenon of cooling region was visualized using visualization device such as He-Ne laser, optical lens, image grabber and CCD camera. When the piezoelectric actuator was applied to the heat transfer process of thermoelectric cooling system, acoustic streaming was occurred in the cooling region. The acoustic streaming was occurred forced convection flow, and was regularly formed the temperature distribution in the cooling region. In the end, the results clearly show that the acoustic streaming is one of the prime effects to enhance the convection heat transfer and cooling effect.
Study on Machining Characteristic of Aeronautical Material under Orthogonal Dry Cutting
Authors: Ginting Armansyah , Nouari Mohammed
Published: July 2011

From a series of experiments carried out in this study, the machining characteristic of aeronautical material, titanium alloy Ti6Al4V, under dry orthogonal cutting is determined by the relations among material removal rate (MRR), tool rake angle (), and the other nine parameters in orthogonal cutting concept. Continuous and serrated chip forms are observed and chip form is determined by the flow localization parameter (). It is found that the critical values of  in which serrated chip formed are ranging from  = 4.71 to  = 5.37 or at the chip load from 0.0045 to 0.006 mm2/min. The number of tooth (frequency) on serrated chip increases with cutting speed (V). The tool failure modes found in this study are normal flank wear, notch wear, chipping and catastrophic failure. Tool chip adhesion caused by adhesive wear mechanism and high rake angle weakened the tool cutting edge play important roles on the failure mode of the straight tungsten carbide cutting tool used in this study.
Effect of Nano Silica on the Sinterability of Hydroxyapatite Dense Bodies
Authors: Tolouei R. , Tan Chou Yong , Singh Ramesh , Sopyan Iis , Teng Wan Dung
Published: July 2011

The effects of adding a small amount of nano silica in hydroxyapatite (HA) on the sinterability and mechanical properties of hydroxyapatite were studied. The starting HA powder was synthesized using a novel wet chemical precipitation method. Different amount of silica powder was mechanically mixed with the synthesized HA. The green samples were subsequently cold isostatically pressed at 200 MPa. Sintering in air was accomplished by firing the green samples at temperatures ranging from 1050°C to 1250°C. Sintered samples were analyzed to determine phase composition and mechanical properties. The XRD analysis revealed that with increasing the amount of silica in the HA powder, decomposition of HA to TCP occurred at sintering temperature higher than 1050°C. The bulk density of all silica-doped samples decreased through the temperature range studied. In agreement with the bulk density trend, the increasing silica additives in HA depleted the Young’s modulus and Vickers hardness of the HA body. The study revealed that the addition of silica have an adverse effect on the sintered properties of hydroxyapatite bioceramics.
Effect of the SiC Content on the Tribological Properties of Hybrid Al/Gr/SiC Composites Processed by In Situ Powder Metallurgy (IPM) Method
Authors: Akhlaghi Farshad , Mahdavi S.
Published: July 2011

The Al/Gr/SiC hybrid composites have attracted a considerable attention owing to their high wear resistance combined with a low friction coefficient. In these composites graphite acts as a solid lubricating agent and lowers the friction coefficient. However, it reduces the mechanical properties of the composite. The presence of hard SiC particles in these hybrid composites increases the hardness and strength and compensates for the weakening effects of graphite. Powder metallurgy (P/M) is an important processing technique for processing of these MMCs but requires a relatively long mixing time for obtaining a uniform distribution of graphite and SiC particles in the matrix alloy. In the present study for the first time a new method, namely "in situ powder metallurgy (IPM)" is applied for preparation of Al/SiC/Gr hybrid composites. In this work, the effects of different contents (0-40 vol.%) of SiC particles on the morphology and size distribution of the IPM produced Al/Gr/SiC powder mixtures containing 9 vol.% of graphite particles was investigated. Then Al/Gr/SiC compacts were prepared by cold pressing of different powder mixtures and after sintering, the effects of SiC content on the density, microstructure, hardness and wear properties of the resultant hybrid composites was investigated.
Investigations about the Single Point Incremental Forming of Anisotropic Titanium Alloy Sheets
Authors: Palumbo G. , Brandizzi Marco , Cervelli G. , Fracchiolla M.
Published: July 2011

The present work focuses the attention on the Single Point Incremental Forming (SPIF) of the Titanium (Ti) alloy Ti-6Al-4V. Tensile tests were carried out using the optical strain measurement system Aramis3D, in order to determine the mechanical behaviour of the alloy and to investigate the anisotropy of such alloy. Finite Element (FE) simulations of the SPIF process (using ABAQUS/explicit) were performed using a simple but non-axialsymmetric shape (truncated pyramid) with the aim of investigating the effect of both the tool/pitch ratio (D/p) and the draw angle (α), taking into account the anisotropic behaviour. The analysis of plastic strains and thinning maps, together with the evaluation of shape errors originated by the forming process, highlighted that the parameter D/p plays a key role in the SPIF. Results from the preliminary FE analysis were used for investigating the production by SPIF of an automotive component (car door shell). A specific subroutine was created by the authors for automatically generating the tool path to be used in both the FE simulations and the manufacturing of parts by SPIF on a CNC milling machine.
Characteristic Study on Micro Aspheric Surface Using Diamond Tool Cutting
Authors: Liu Yung Tien , Chang Wei Che
Published: July 2011

Due to performance improvement and the trend of miniaturized sizes in optical devices, the need for micro lenses is increasingly presented. In this paper, characteristic study of a micro aspheric mold having a diameter of only 0.3 mm was performed. According to the experimental results of rough cuttings using a diamond tool, the machined surfaces were with a mean peak-to-valley (PV) form error of 1.47 µm. The Taguchi Method was employed to determine the optimal cutting parameters by selecting the cutting depth, work spindle speed, and compensation ratio as the control factors. Experimental trials were conducted according to the L9(34) orthogonal array (OA), and a mean PV form error of 0.79 µm was obtained due to compensation cuttings. Based on signal-to-noise (S/N) ratios, the optimal levels of control factors were determined. By performing the confirmation test, the PV form error was reduced from rough cutting of 1.49 µm to 0.60 μm. The effectiveness of using the Taguchi Method was demonstrated. The systematic approach performed in this paper can be applied to micro-fabrications for precision components in molds and dies industry.
Strip Casting of 6061 and Recycled 6061 Alloy by an Unequal Diameter Twin Roll Caster
Authors: Haga Toshio , Inui Hideki , Nakamura Ryoji , Kumai Shinji , Watari Hisaki
Published: July 2011

A 6061 aluminium alloy and an alloy with increased Fe content, representing recycled 6061 aluminium alloy were cast into strips at speed of 30m/min by an unequal diameter twin roll caster. The Fe content of 6061 aluminium alloy and the model of recycled 6061 aluminium alloy was 0.36 mass% and 0.59 mass%, respectively. Ripple marks, which are typical surface defect of roll cast strips, did not occur on the surface of both as-cast strips. Fe content did not influence the surface condition of the roll-cast-strip. The as-cast strip was cold rolled down to 1 mm, T4 heat treatment was conducted, and then subjected to180 degrees bending test. The result of 180 degrees bending test shows that roll cast 6061 aluminium alloy and 6061 aluminium alloy with increased Fe as recycled had bending ability as same as that of roll-cast 6022 aluminium alloy. In the strip cast by the twin roll caster of the present study, increased Fe content did not influence on the result of the180 degrees bending test.
A Study on the Tensile Property of Jute Yarns Using Weibull Distribution
Authors: Shaha S.K. , Dyuti S. , Ahsan Qumrul , Hasan Mahbub
Published: July 2011

The characteristics of natural yarns are inconsistent in their mechanical property. The tensile strength of jute yarns is an intricate parameter, which can not be fully described using single value. This necessitates the study of the jute yarn strength distribution and efficient experimental methods for its measurement. Here Weibull model is used to describe the statistical nature of the tensile strength. However, the experimental process widely uses for obtaining the two parameters Weibull model which is described for this experiment. The Weibull modulus of the untreated and NaOH treated jute yarns were determined and it suggests that the treated yarns are better than the untreated yarns. The tensile strength of NaOH treated jute yarns increased to 219.93 MPa compared to the untreated yarns which was 177.32 MPa. For the treated yarns the coefficient value R2 is 0.9829, which indicates good degree of linearity.
Effect of Alkali Treatment on Surface Morphology and Properties of Jute Yarns
Authors: Shaha S.K. , Dyuti S. , Ahsan Qumrul , Hasan Mahbub
Published: July 2011

Due to the environmental issue, natural fibers are day by day becoming attractive to researchers. Natural fiber contains cellulose, hemicelluloses, lignin etc, which are hygroscopic in nature and biodegradable. The lack of surface feature diminishes its properties. So, the surface properties of the jute yarns need to be modified. In the present study, jute yarns were cleaned using 2% detergent and chemically modified by 5, 15 and 25% NaOH solution both at room temperature and 700C for 2 hours and dried in air. The structural and morphological studies of the treated and untreated yarns were carried out using Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). The thermal and mechanical behaviour of the yarns were analyzed using Differential scanning calorimetry (DSC) and Instron Universal testing machine. The results show the improvement in mechanical strength of the yarns due to the change in crystalinity after alkali treatment. Also, the thermal decomposition temperature of raw jute yarns decreased from 357.30C to 349.60 C after alkali treatment.
Wear Characteristics of Fe-C-Si and Fe-C-Al Cast Irons
Authors: Shaha S.K. , Haque Mohammad M. , Khan Ahsan Ali
Published: July 2011

In order to study the wear properties of Fe-C-Si and Fe-C-Al alloy systems, castings were produced in resin bonded sand mould of suitable design, which provides information regarding various thicknesses of the castings. Gray cast iron is an inexpensive and readily available material used for manufacturing of roller, roller shell, piston rings, cylinder liners, etc. Its low melting point is characterized as unique combination of superior properties like good friction and wear properties and economic in manufacturing. In the present study, wear behavior of the Fe-C-Si and Fe-C-Al cast irons were investigated using a pin-on-disk type apparatus at room temperature. Alumina ball of 3 mm diameter was used as pin, while the cast sample served as the disk. The tests were carried out at a normal load of 5.0 N and a sliding velocity of 250 mm/s for 30 min. The Fe-C-Al cast iron showed a wear rate of 3.3203×10-5 mm3/m/N compared to 12.42×10-5 mm3/m/N of Fe-C-Si cast iron. The worn surfaces were analyzed using optical profilometer and SEM.
Study on the Microstructure and Properties of Fe-C-Si and Fe-C-Al Cast Irons
Authors: Shaha S.K. , Haque Mohammad M. , Khan Ahsan Ali
Published: July 2011

Two types of cast irons with Fe-C-Si and Fe-C-Al. alloy systems were investigated in the present study. In order to modify the microstructure and properties of cast iron, Al was added to low silicon pig iron that is in Fe-C-Al (Sorel metal) alloy system. Its effect was then studied with comparing to normal Fe-C-Si alloy system. Both cast irons were produced in sand mould of suitable design to provide all information regarding the structure and properties. The microstructure was analyzed using optical microscope which showed the distribution of graphite flakes in pearlite or ferro-pearlite matrix. The size of the graphite flakes in Fe-C-Al system was smaller and more evenly distributed compared to the Fe-C-Si alloy system. The cast product was also characterized by using XRD. The maximum hardness of the Fe-C-Al alloy was measured as 110.2 HRB compared to 89.32 HRB of the conventional Fe-C-Si alloy system. The impact test results showed that Fe-C-Al cast iron has higher impact property than Fe-C-Si cast iron.
Improvement of Local Decrease in Material Thickness of Fuel Supply Pipe
Authors: Kamei Nobuyuki , Watari Hisaki , Hatano T. , Kawamura Youichi
Published: July 2011

Growing demand for lightweight products has been increased by the rapid development of automobiles since the global environment conservation meeting at Kyoto. Lighter products have been necessary when considering in taking action to reduce fuel consumption. One of the key is the utilization of high strength and light materials, such as stainless, high-tensile strength steels and magnesium alloys, which are difficult to be formed due to their high strength compared to normal steel pipes. This paper is concerned with the development of pressing technology that copes with forming relatively high strength stainless pipe with screw threads on the surface of pipes. Our new press-forming process in order to obtain accurate screw threads on the stainless pipe was tested. A 3-D digitizer was used for the measurement of the accuracy of manufactured pipes by the proposed pressing method. It is found that the proposed our press-forming was effective to improve decrease of pipe thickness compared to conventional roll forming technology. The maximum decrease in material thickness was 20% using our press-forming process for screw threads in the formed pipe.
Orthogonal Array Technique for Optimizing the Sintering Parameter of the Metal Injection Molding (MIM) Compact: Best Flexure Strength
Authors: Jamaludin Khairur Rijal , Muhamad Norhamidi , Rahman Mohd Nizam Ab. , Ahmad Sufizar , Ibrahim Mohd Halim Irwan , Nor Nor Hafiez Mohamad
Published: July 2011

Sintering is a key step in the metal injection moulding (MIM) process, which affects the mechanical properties of the sintered part. The mechanical property of the sintered compact is resulted from tremendous sintered part densification. The paper presents an optimisation of the sintering parameter for the best flexure strength of the fine SS316L water atomised powder compact. The L9 (34) orthogonal array is used in the study and four replication of the flexure strength has been recorded at each experiment trial. The analysis of variance (ANOVA) signifies the sintering variables are highly significant to the flexure strength, α = 0.005. The study demonstrates that the cooling rate is the most influential variable that contributes to the best flexure strength, followed by heating rate, dwell time and sintering temperature.
Effect of Pouring Temperature and Melt Treatment on Microstructure of Lost Foam Casting of AL-Si LM6 Alloy
Authors: Karimian Majid , Ourdjini Ali , Idris Mohd Hasbullah , Bsher M. , Asmael A.
Published: July 2011

This paper presents the experimental investigation conducted on Al-Si cast alloy (LM6) cast using lost foam process. The main objective of the research is to investigate the effect of pouring temperature, section thickness and melt treatment on the microstructure of the lost foam casting of Al-Si alloy. Step pattern with five different sections was prepared from 20 kg/m³ density foam and poured at five different temperatures; 700, 720, 740, 760, and 780 with and without the addition of AlTiB as grain refiner. Analysis on microstructure, eutectic silicon spacing and porosity percentage were conducted to determine the effect of both parameters. The results show that pouring temperature has significant influence on the quality as well as microstructure of the lost foam casting of LM6 Al-Si alloy. Lower pouring temperature was found to produce finer microstructure casting. However, the addition of AlTiB as grain refiner did not affect the produced castings significantly whether in terms casting quality or microstructure.
Finite Element Analysis and Die Design of Extrusion Processes of Radial-Finned Heat Sink
Authors: Chen Dyi Cheng , Chen Jhih Ming , Guo Ming Wei , Jao Chih Hsuan , Chen Wen Jong
Published: July 2011

There are many different types of manufacturing methods for heat sink fins in the current market. The aim of this study is to design an extrusion die for a radial-finned heat sink using a commercial finite element package, DEFORMTM 3D. We then conduct a series of simulation analyses with different variables such as friction factor, ram velocity, and fin gate stage of the die to evaluate the methods of decreasing the warping in the extrusion process. The die is assumed as a rigid body in the analyses. The results confirm the suitability of DEFORMTM 3D to design an extrusion die achieving a lower warping behavior of the radial-finned heat sink.
On the Dependence of Microstructure-Sensitive Properties of Cast 2xxx Series Aluminium Alloy on Solidification Parameters
Authors: Amuda M.O.H. , Oladoye A.M. , Agunsoye J. , Farombi O. , Subair W.
Published: July 2011

The effect of casting temperature, cooling rate in silica bound molding sand and modifier additions on tensile, ductility and hardness properties Al-Cu binary alloy is presented. The study revealed that casting at high cooling rate and low casting temperatures with sufficient addition of ferro-silicon not exceeding the limited concentration for solubility improve mechanical properties of castings. The study also indicated that casting temperature greater than 7000C expanded the liquidussolidus solidification line leading to multiple phase formation which in-turn affect the final microstructure. Casting temperature of 7000C, addition of modifier in amount up to 200g and rapid cooling rate optimized the mechanical properties. The microstructure in this condition consists of equiaxed grains with spot presence of CuAl2 intermetallics which probably is responsible for the increased tensile strength and marginal change in ductility.
A Novel Scheme for Weld Microstructure Control Using Cryogenic Cooling
Authors: Amuda M.O.H. , Mridha S.
Published: July 2011

In this work, the preliminary result on the effect of cryogenic cooling on grain growth in weld is reported. Ferritic stainless steel weld produced under TIG torch in argon environment is cooled in liquid nitrogen. The weld structure is characterized using LOM, SEM and EDX spectroscopy. The results suggest that cryogenic cooling reduced the weld width within 2% to 5% and HAZ to 39% relative to those cooled in normal condition. This ensures that the area of the base metal affected and exposed to the weld thermal cycle is reduced and hence probably generates less metallurgical distortion. The cryogenic cooling also generated 14% to 36% grain refinement compared to welds cooled in normal condition.
Investigation on Joint Strength of Dissimilar Resistance Spot Welds of Aluminum Alloy and Low Carbon Steel
Authors: Mortazavi Seyedeh Nooshin , Marashi Pirooz , Pouranvari Majid , Masoumi Maryam
Published: July 2011

Resistance spot welding was used to join low carbon steel and A5250 Aluminum alloy sheets. Mechanical properties and failure behavior of the spot welds in terms of peak load, failure energy and failure mode, were evaluated using tensile- shear test. Relationship between welding current and mechanical properties was investigated. It was found that the formation of brittle intermetallic compounds in the weld fusion zone is the key governing factor for mechanical properties of dissimilar Al alloy/low carbon steel resistance spot weld. Increasing welding current, increases both peak load and energy absorption due to increasing overall bond area and transition in failure mode from interfacial to pullout failure mode.
Design and Simulation on Compressor Metal Matrix Composite by Investment Casting
Authors: Taufik  , Sulaiman Shamsuddin , Abdullah T.A. , Sivarao
Published: July 2011

Compressor is a part of turbocharger approaches that utilize the exhaust gas of an automobile to drive the compression device. The purpose of turbocharging is to increase the intake pressure and the amount of air into the combustion chamber to improve the efficiency of the engine. Compressor impeller determines the service life of the turbocharger. This paper proposes the new methodology of producing the compressor impeller using Metal Matrix Composite (MMC) material by investment casting. In general, this study presents the tasks pertaining to metal matrix composites and their interactions in designing of compressor impeller. This study presents the use of genetic algorithm (GA) and computer programs for designing a new compressor and determined the wax pattern dimensions based on three-dimensional finite-element simulations as a preliminary study by using investment casting method. The model of thermal and mechanical analysis was developed by ANSYS. As the results, the simulation model was generated and it could be used for improving the design of turbine-compressor assembly through the bottom geometry changes of the compressor.