bluuebunny/crossref_metadata_2025 huggingface dataset:
UV/H2O2 Process for Removal of Total Organic Carbon from Refinery Effluent: Screening of Influence Factors Using Response Surface Methodology
Authors: Harimurti Sabtanti , Ur Rahmah Anisa , Aziz Omar Abdul , Murugesan Thanapalan
Published: June 2014

Effluent containing high concentration of alkanolamine from a sweetening process of natural gas plant is commonly generated during maintaining, cleaning and scheduled inspection of the absorption and desorption column. The effluent is not readily biodegradable and cannot be treated in the conventional biological treatment. Advanced oxidation processes (AOPs) is a promising method for the treatment of recalcitrant organic contaminant. Most methods used are Fenton reagent, UV/Ozone and UV/H2O2. Based on the advantages of the UV/H2O2such as no formation of sludge during the treatment, high ability in production of hydroxyl radical and applicable in the wide range of pH, the UV/H2O2has been chosen to treat the effluent from refinery plant, which has high concentration of methyldietnaolamine (MDEA). The factors influencing in the degradation of refinery wastewater that contain MDEA were screened using response surface methodology (RSM). It was found that degradation process of the refinery effluent was highly dependent on oxidant concentration (H2O2) and initial pH. Temperature of oxidation process was found oppositely. Since the temperature gave insignificant effect on the TOC removal process, hence the independent factor temperature will be eliminated during the further optimization process condition of degradation. Thus, the optimization process condition of degradation will be more effective and simpler.
A Review on the Viscous and Thermal Transport Properties of Nanofluids
Authors: Umer Ilyas Suhaib , Pendyala Rajashekhar , Shuib Anis , Marneni Narahari
Published: June 2014

In modern science and engineering nanofluids are playing a vital role in the application of heat transfer devices due to their effective properties. Addition of nanoparticles in the fluid can alter thermophysical properties of the nanofluid. Experimental and theoretical studies are essential to understand the change in fluid dynamics aspects of the fluid by the addition of nanoparticles. This paper presents a brief review on the viscous and thermal transport effects of nanofluids. The main emphasis is on the comparison of previous theoretical and experimental studies for thermophysical properties of nanofluids. These properties include density, viscosity, thermal conductivity and specific heat capacity of nanofluids.
A Taguchi-SQP Approach for Minimizing Energy per Unit Diesel Production at Crude Distillation Unit
Authors: Zainal-Abidin Mardhati , Yusoff Nooryusmiza , Siraj Khairiyah Mohd
Published: June 2014

Crude distillation unit (CDU) is one of the largest energy consumer units in a refinery. It consumes around 35-40% of the total process energy in refinery. This paper presents a systematic approach for selecting optimization variables using Taguchi method. These variables are subsequently employed in minimizing energy consumption per unit diesel production at CDU. A steady state model of the CDU was developed under the HYSYS 7.2 environment and utilized to demonstrate the efficacy of this method. Optimum energy consumption per unit diesel production obtained from Taguchi were validated by comparing the results with those obtained from HYSYS built-in SQP solver. The results reveal that the combination of Taguchi and SQP solver can reduce CPU time for optimization purposes.
Performance Study of Ni Catalyst with Quicklime (CaO) as CO2 Adsorbent in Palm Kernel Shell Steam Gasification for Hydrogen Production
Authors: Khan Zakir , Yusup Suzana , Ahmad Murni Melati , Lai Fui Bridgid Chin
Published: June 2014

There is a need to search for efficient material that reduce CO2content and enhance the hydrogen composition in the product gas from biomass steam gasification particularly for large scale production. The present study was carried out to perform the characterization of commercial quicklime as CO2absorbent and Ni powder as catalyst. The chemical composition of the materials perform using x-ray fluorescence (XRF) indicated high amount of CaO and Ni in the bulk samples. Using XRF and SEM analyses, it was found that both materials showed high crystalinity. The adsorption isotherm from physisorption analysis suggested that the materials exhibits Type II category according to the IUPAC classification scheme. These types of material exhibit mesoporous structure which was also verified by the pore size of the samples found via BET analysis. The BET surface area reported was 4.16 m2/g and 0.78 m2/g for quicklime and Ni powder, respectively. In conclusion, commercial quicklime has the potential as CO2absorbent, based on the pore size and surface area. Conversely, the surface properties of the Ni powder were found relatively lower as compared to other commercial catalysts available for biomass steam gasification.
Density, Viscosity and CO2 Solubility of Novel Solvent
Authors: Kee Wong Mee , Mohd Shariff Azmi , Bustam Mohammad Azmi , Keong Lau Kok , Karikalan Turgkaraaj , Murshid Ghulam
Published: June 2014

Carbon dioxide (CO2) is the major cause of accelerating global warming. It is important to employ efficient method to capture CO2. Absorption is the most established technique to separate CO2 and amines are most commonly used as solvent. In this study, density and viscosity of an amine based novel solvent named Stonvent were investigated at temperature ranging from 298.15 K to 338.15 K. CO2 solubility in Stonvent was measured at varying pressures, temperatures and concentrations. The experiments were conducted at temperatures (303.15, 318.15 and 333.15) K, and at pressures (0.5, 1, 1.5 and 3) MPa over a wide range of concentration (10, 20, 30 and 100) mass %. Solubility of CO2 was determined from pressure drop due to absorption of CO2 into solvent within equilibrium cell. Absorption capacity of Stonvent increases significantly with increasing pressure. Solubility of CO2 in Stonvent is higher compared to Monoethanolamine (MEA), 1-amino-2-propanol (MIPA) and 2-amino-2-methyl-1,3-propanediol (AMPD) at elevated pressure, hence posing Stonvent as an attractive alternative for acid gas absorption in high pressure conditions. Substantial increase in CO2 loading was observed when concentration of Stonvent is increased and when temperature is decreased.
Preparation and Characterization of Polysulfone Membrane for Gas Separation
Authors: Jusoh Norwahyu , Keong Lau Kok , Mohd Shariff Azmi
Published: June 2014

Symmetric and asymmetric polysulfone membranes were fabricated using different of solvents; N-methyl-pyrrolidone (NMP), Tetrahydrofuran (THF) and Dimethylacetamide (DMAC) at different polymer concentration (15 and 20%) to study the influence of varying type of solvents and polymer concentration in membrane fabrication. The membranes were characterized using Field Emission Scanning Electron Microscopy (FESEM), Thermogravimetric Analyzer (TGA), Universal Testing Machine (UTM) and Fourier Transform Infra-Red (FTIR).The results disclosed that the symmetric, higher polymer concentration membrane contributed to better thermal and mechanical stabilities. PSF/THF membrane showed good mechanical strength while PSF/DMAC membrane illustrated great thermal stability. 20% of polymer concentration and PSF/THF membrane led to the thicker skin layer and dense structure formation.
Preliminary Study of Rambutan (Nephelium lappaceum) Seed as Potential Biocoagulant for Turbidity Removal
Authors: Zurina Abidin Zainal , Mohd Fadzli Mohamed , Abdul Ghani Liew Abdullah
Published: June 2014

This experiment was performed to determine the ability of the coagulation performance of rambutan seed in comparison to alum for potential use in turbidity removal in water and wastewater treatment industry. Experiments were conducted to find the optimum operating conditions for coagulation process such as coagulant dosage and pH and also suitable extracting solvent for the active agent (distilled water, NaCl and NaOH). 1 M NaCl was found to be an effective solvent for extracting the active coagulant agent in rambutan seed and gave about 99 % turbidity removal. The optimum rambutan seed dosages and pH was 100 mg/l and pH 3, resulting in > 90% turbidity removal. In order to reduce dependency on alum, 50% alum and 50% rambutan seed as coagulant combination was used in the order of alum first followed by rambutan seed. The highest turbidity removal of 99% was achieved compared to when using alum (91%) and seed (88%) alone. Rambutan seed coagulant exhibited faster sedimentation time due to bigger flocs formation and also smaller sludge volume than alum. The results suggest potential of using rambutan biomass as biocoagulant. Keywords: rambutan seed, alum, protein, natural coagulant, turbidity, solvent
Behavior of Scandium in Aluminum Alloys of Different Alloying Systems
Authors: Ovsyannikov Boris V. , Zamyatin Viktor M.
Published: June 2014

Microstructure and composition of elements in phases of homogenized ingots in aluminum alloys of various alloying systems: Al-Mg-Mn-Si, Al-Mg-Si-Cu, and Al-Zn-Mg-Cu, were examined using a method of scanning electronic microscopy and X-ray microanalysis. Besides basic alloying elements of magnesium, zinc, copper, silicon, and manganese, alloy composition contained additional alloying elements, including zirconium and scandium. Presence of intermetallic compounds of various chemical composition insoluble during ingot homogenization was found in microstructure of examined samples. It is found that zirconium and scandium are jointly present in composition of some intermetallic compounds containing additional alloying elements of alloys.
The Role of Vacancies in the Aging of Al-Mg-Si Alloys
Authors: Pogatscher Stefan , Werinos Marion , Antrekowitsch Helmut , Uggowitzer Peter J.
Published: June 2014

In this paper the role of vacancies in the aging of Al-Mg-Si alloys is examined and novel concepts to improve their aging behavior are presented. It has been proposed that the technologically favored fast nucleation of the major hardening phase during artificial aging requires quenched-in vacancy assisted diffusion. The well-known interdependence of natural aging and subsequent artificial in Al-Mg-Si alloys can be understood in terms of quenched-in vacancy trapping in Mg/Si-clusters formed during natural aging. Diffusion during artificial aging is then determined by the dissolution of these vacancy-containing Mg/Si-clusters. This simple concept can guide the development of strategies to avoid the negative effect of natural aging. It is shown that the aging behavior of Al-Mg-Si alloys can be improved not only by processing related measures, but also by compositional interventions, which apply the following recipe: (i) avoid the trapping of vacancies in Mg/Si-clusters, (ii) prevent the vacancy annihilation during RT, and (iii) make them available for diffusion during artificial aging. It is shown that this strategy can be executed in Al-Mg-Si alloys by adding defined trace amounts of elements with an attractive binding energy to vacancies and sufficient solubility in the aluminum matrix.
The Development of a Brazing Sheet Core Alloy with Excellent Post Braze Properties
Authors: Ahmed Hany , Kadali Jyothi , Gatenby Kevin , Howells Andrew
Published: June 2014

The heat exchanger market requires aluminum brazing sheet that offers a good balance of properties, namely: corrosion resistance, brazability, and post braze strength. A new long life brazing sheet alloy which has attractive properties in the post braze condition has been developed. Specifically, higher post braze strength and improved air side corrosion resistance has been obtained. In addition, a deeper understanding of dense precipitate band (DPB) formation in higher Si containing core alloys during brazing has been developed. The new alloy will lead to improvements in radiator tube stock performance.
Microstructure and Mechanical Properties of D-SSF Processed Al-Zn-Mg Alloys with High Fe Content
Authors: Aoki Takuro , Kobayashi Equo , Sone Masato , Sato Tatsuo
Published: June 2014

Microstructures and mechanical properties of the D-SSF (Deformation Semisolid Forming) processed Al-Zn-Mg alloys with high Fe content up to 2 mass% were investigated. A high ductility alloy even containing 1 mass% Fe was successfully produced by applying the D-SSF process. Especially, the D-SSF processed alloy with 1 mass% Fe was superior to the conventionally processed alloy with Fe-free in the properties of the tensile strength and elongation. These results clearly indicate that the harmful influence by the addition of 1 mass% Fe is effectively modified into not harmful one by applying the D-SSF process. Furthermore, the former liquid phase regions (FLP regions) which are finally solidified during the D-SSF process are completely extinguished by the solution treatment and resultantly the mechanical properties are greatly improved. The extinction process of the FLP regions during the solution treatment was examined using an EBSD method in terms of the crystal orientations of the α-Al grains.
The Effect of Homogenization Conditions on Extrusion Texture and Microstructure Evolution in AA3003
Authors: Chen Jing Qi , Poole Warren J. , Parson Nick C.
Published: June 2014

Two different conditions were used to study the effect of homogenization on extrusion texture and microstructure evolution in AA3003. The first condition considered homogenization for 8 h at 500°C to obtain a high density of dispersoids and the other condition was homogenized for 24 h at 600°C to produce a sample with a very low density of dispersoids. After uniaxial extrusion at 400°C with a speed of 32 mm/s and an extrusion ratio of 70:1, the material with a high density of dispersoids formed <001> and <111> double fibre texture in the centre of extrusion rod and a smeared texture from <011> to <111> near the surface. For the material without dispersoids, only <001> texture fibre is observed in the centre of extrusion rod and a strong <011> fibre is observed near the surface.
Experimental and Numerical Investigations of the Plastic Deformation during Multi-Pass Asymmetric and Symmetric Rolling of High-Strength Aluminum Alloys
Authors: Ma Cun Qiang , Hou Long Gang , Zhang Ji Shan , Zhuang Lin Zhong
Published: June 2014

For understanding the distribution of plastic deformation induced by asymmetric rolling (ASR), multi-pass ASR and symmetric rolling (SR) experiments combined with the finite element simulation were used for high-strength aluminum alloy in the present study. The influence of reduction per-pass on the shear / effective strain distributions were studied via different ASR processes. By measuring the shear angle (θ, the angle between the reference mark before and after rolling) of rolled sheets, redundant shear strain and equivalent strain were calculated. It is shown that with equal total thickness reduction for ASR and SR, ASR can induce much more shear deformation through the thickness. By calculating the evolution of redundant shear strain and total equivalent strain for different ASR routines, it indicates that small pass reduction could be much favorable to the strain accumulation than that of the large pass reduction under a same total reduction in ASR process. Also, the influence of shear stress on the strain distribution and the through-thickness strain distribution were studied and evaluated with FEM analyses.
Effect of Zr Addition on Recrystallization Behavior of Extruded Al-Mg-Si Alloys Containing Mn
Authors: Ihara Kentaro , Shikama Takahiro
Published: June 2014

Effects of Zr addition on recrystallized structure and texture in extruded Al-Mg-Si alloy containing Mn have been investigated. Materials were homogenized at temperatures in the range 550 °C to 590 °C and extruded at 500 °C at the speed of 10m/min. In extruded Al-Mg-Mn-Si-Zr alloy, the fraction of Cube oriented grains reached 40% as homogenization temperature raised to 590 °C. On the other hand, the fraction of Cube oriented grains in extruded Al-Mg-Mn-Si alloy was limited to 20-30 %. In addition, to clear the formation process of recrystallized grains in these alloys, observation of hot-compression deformed and recrystallized grain structures were carried out. It was suggested that moderate Zener drag promoted the preferential recrystallization of cube oriented grains
Effect of Extensive Isothermal Rolling on Microstructure and Mechanical Properties of an Al-Mg-Sc Alloy
Authors: Kulitskiy Vladislav , Malopheyev Sergey , Kaibyshev Rustam
Published: June 2014

The evolution of microstructure and mechanical properties of an Al-5.4Mg-0.4Mn-0.2Sc-0.09Zr alloy subjected to rolling at 300oC was studied. It was shown that the rolling of the alloy leads to strong anisotropy in mechanical properties. The formation of the lamellar structure occurs at a total reduction of 60% due to alignment of initial boundaries along rolling direction (RD), and appearance of geometrically necessary boundaries (GNB) aligned with {111} planes. This process is accompanied by a strong increase in the lattice dislocation density by a factor of 50. Further rolling induces the formation of subgrains within lamellar structure that diminishes the anisotropy. The GNBs have low-angle misorientations, initially. After a reduction of 80%, minor part of GNBs acquires high-angle misorientation. The formation of well-defined subgrains within lamellas leads to a decrease in the lattice dislocation density by a factor of about 10; the yield stress (YS) decrease is -25% along the RD. At the same time the YS in the transverse direction tends to increase with increasing reduction from 60 to 80%. The effect of the deformation structure on the mechanical properties and their anisotropy is discussed.
Effects of Thermo-Mechanical Treatment on the Microstructure of AA7085 Aluminum Alloy
Authors: Tong Hong Wei , Liu Wen Yi , Huang Guang Jie , Liu Qing
Published: June 2014

The microstructure of pre-aged AA7085 rolled plate was studied by means of hardness tests, optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and electrical conductivity tests. The results show that supper refined and homogeneous precipitates were formed during pre-aging, but the hardness of the alloy was still relatively low. There occurred a large number of dislocations when the warm deformation was introduced, and the size of the intragranular precipitates firstly increases and then decreases and then increases with the dislocation density increasing, which was caused by the role of dislocations on inhibiting the formation of GP zone and promoting the nucleation and transformation of η phase. Meanwhile, the distribution of grain boundary precipitates also changed from continuous chain to coarsening interrupted distribution and the precipitate free zone (PFZ) broadened obviously.
Microstructure and Properties of Al-Mg-Si Wire-Rod Subjected to Continuous Heat Treatment
Authors: Osuch Piotr , Walkowicz Monika , Smyrak Beata , Knych Tadeusz
Published: June 2014

Among multiple applications 6XXX-series aluminum alloys are widely used as electrical conductor for overhead power lines. For that application Al-Mg-Si alloys are produced mainly in the form of wire rod in the continuous casting and rolling lines (CCR). There is many technological routes possible to transform the Al-Mg-Si wire-rod into precipitation hardened, ready to use Al-Mg-Si wires. One of these routes involves using the heat of continuous casting and rolling process to artificial ageing of wire-rod, which is motivated by ecological premise. In the current paper the results of continuous heat treatment of the wire-rod within the CCR line (involving quenching of the alloy to artificial ageing temperature) on the microstructure and properties has been examined. It was shown the structure of wire rod formed in such process is very irregular. TEM investigations has shown that many heterogeneous particles are present and the arrangement of the β main hardening phase is very inhomogeneous with wide precipitate free zones occurred. However this type of microstructure has a positive effect on electrical properties of the material in question, which is important taking into consideration application of the alloy.
Self-Hardening Alloys for Automotive Application
Authors: Peter Ildiko , Rosso Mario , Castella Christian , Molina Roberto
Published: June 2014

In this paper a self-hardening Al-based alloy (AlZn10Si8Mg) is proposed for automotive applications as an alternative to the A357 (AlSi7Mg0.6) T6 heat treated alloy. The properties of the AlZn10Si8Mg alloy have been monitored and compared to those of the A357 alloy which is already employed in the targeted automotive industry. The samples have been submitted to microstructural analysis and mechanical characterization, while the presence of defects on the fractured surface has been identified by fracture surface analysis. A relationship between defects and mechanical performances has been identified. The corrosion resistance of the alloys has also been investigated according to the Standard BS 11846. On the basis of the results obtained till now, the AlZn10Si8Mg alloy is a good candidate for the proposed automotive application.
Formation of Microstructural Gradient of A2017 by RBT at Ambient Temperature
Authors: Ueno Kouki , Sato Akira , Sato Hiroyuki
Published: June 2014

Distribution of microstructure and hardness by RBT (Rotary Bending and Tensile) loading at ambient temperature is presented. Grain size is one of the important parameters of microstructures of alloys, and affects mechanical characteristics depending on deformation conditions. At higher temperatures, coarsening of grain size improves creep strength, while the finer improve tensile strength at ambient temperature. Grain size shows opposite effect on strength of alloys depending on temperatures and not always possible to improve strength both at ambient and high temperatures. Authors have attempted microstructural control by formation of distribution of plastic strain prior to heat treatment of aluminum alloys to obtain well-balanced strength both at high and ambient temperatures. In this report, distribution of grain size and hardness in 2017 aluminum by RBT loading are presented, and compared with results in 1070 reported previously. RBT loading equipment is designed for combined loading by rotary bending and static tensile loading to distribute plastic strain. In 2017 alloy, obtained microstructure after suitable heat treatment show distribution of hardness, while grain size show homogeneous distribution. The distributions, however, are different from that in 1070 alloy.
Ageing of Brazed Aluminium AA6xxx Alloys for Vehicle Radiators
Authors: Stenqvist Torkel , Bång Kristoffer , Kahl Sören , Contet Arnaud , Karlsson Oskar
Published: June 2014

Some aluminium alloys with Mg-Si age-hardening are used in vehicle radiators. For cost reasons they are preferably delivered in a naturally aged temper. Estimated minimum time of natural ageing between brazing and when the radiator is taken into service is 14 days. At the service temperature of 95°C, the radiator material will continue to age harden. For accelerated durability testing it is vital to use a radiator with the strength and ageing response of a service radiator. We investigated whether the full 14 days of natural ageing were needed, or if the time could be shortened. Since a vehicle is not in constant use, the radiator temperature will vary over time. We therefore compared cyclic ageing between ambient temperature and 95°C to continuous ageing at 95°C. The Sapa Heat Transfer alloys FA7870 (for headers) and FA7850 (for tubes) were subjected to different ageing times at different temperatures. Tensile and hardness were performed to assess the ageing effect. It was found that natural ageing reduced hardening during the subsequent ageing at service temperature ageing effect, an effect that was most pronounced for the first four days. There was no difference between continuous and cyclic ageing.
A Novel Ultrasonic Casting Process Using Controlled Cavitation and Melt Flow in Hot Top Molds
Authors: Komarov Sergey , Ishiwata Yasuo , Takeda Yoshihiro
Published: June 2014

The present work introduces a novel ultrasonic DC casting process which allows producing billets of hypereutectic Al-Si alloys with greatly refined and uniformly distributed particles of primary Si. In the process, ultrasonic vibrations are introduced into an Al-17Si-0.01~0.03P melt in a hot top positioned on the mold by using a high-amplitude ceramic sonotrode. The hot top design and sonotrode arrangement provided a highly effective cavitation treatment of the melt in the hot top and well-controlled flow in the sump. A simplified model is proposed to explain the obtained results.
Recrystallization Behavior of Twin-Roll Cast 3xxx Series Aluminum Alloy
Authors: Yoshino Michihide , Iwao Shohei , Edo Masakazu
Published: June 2014

Twin roll casting (TRC) is an efficient process used to produce thin plates directly from molten metal. However, TRC has a much higher cooling rate during solidification compared with conventional direct chill casting. Accordingly, the constituent phases are refined and the added elements are supersaturated by this casting method. Supersaturation of the added elements hinders both recovery and recrystallization because fine dispersoids precipitate from the supersaturated solid solution during annealing [ and coarsen the grain size of the final plate, which leads to degradation of formability. Therefore, it is important to understand the influence of the solute element and dispersoids on recrystallization behavior to obtain an appropriate grain structure for forming. In this study, the effects of the homogenization conditions and cold rolling reduction on the recrystallization behavior of twin-roll cast 3XXX series aluminum alloy were investigated.
Study on the Asymmetric Hot Rolling of Aluminium Alloy Thick Plate
Authors: Zuo Yu Bo , Fu Xing , Cui Jian Zhong , Wang Ping , Li Lei , Wang Xiang Jie
Published: June 2014

The development of aviation industry demands hot rolled aluminium alloy extra thick plates. However, it is quite difficult to obtain sufficient and uniform deformation of extra thick plate by conventional hot rolling process. The asymmetric hot rolling can generate an additional shear deformation and significantly improve the equivalent strain at the centre of the plate and consequently the uniformity of the microstructure, and mechanical properties. In the present work, the asymmetric rolling (ASR) was achieved by adjusting the diameters of the upper roll and the lower roll and was used to prepare hot rolled thick plate of an aluminium alloy. The effect of the asymmetric hot rolling process on the deformation, shape control, microstructure and mechanical properties was experimentally studied. The results showed that the ASR has a significant effect on metal deformation and can somehow refine microstructure and improve the uniformity of microstructure and properties although plate bending often happens during rolling process. This paper presents these results and gives corresponding discussions.
The Heat Treatment of Rheo-High Pressure Die Cast 6xxx Series Al-Mg-Si-(Cu) Alloys
Authors: Möller Heinrich , Daswa Pfarelo , Govender Gonasagren
Published: June 2014

Limited information is available regarding the heat treatment response of age-hardenable wrought Al-alloys produced by semi-solid metal forming. In this study, the effects of chemical composition, natural pre-ageing and artificial ageing on the T6 properties of rheo-high pressure die cast 6xxx series Al-Mg-Si-(Cu) alloys are investigated. A Cu-free alloy 6082 is compared with Cu-containing alloys 6013 and 6111. The effects of Mg:Si ratio of the alloys are also quantified by means of a comparison between alloys 6111 and 6013. Artificial ageing curves following either no or 5 days of natural pre-ageing are also presented.
Beware of Grain Refinement
Authors: Ovsyannikov Boris V.
Published: June 2014

Recently significant successes have been achieved in the field of grain refinement by means of such additives as the titanium, zirconium, scandium, AlTiB and AlTiC. However, introduction of grain refining additives results to a number of negative effects. These effects can be divided into four basic groups: 1. Reduction of high-strength alloy casting properties. 2. Defects of structure. 3. Intermetallic and oxide inclusions. 4. Decrease in mechanical and fatigue properties of the semis made of ingots with fine grain.
Melt Conditioned Direct Chill Casting (MC-DC) Process for Production of High Quality Aluminium Alloy Billets
Authors: Patel Jayesh B. , Li Hu Tian , Xia Ming Xu , Jones Simon , Kumar Sundaram , O'Reilly Keyna , Fan Zhong Yun
Published: June 2014

A novel direct chill (DC) casting process, melt conditioned direct chill (MC-DC) casting process, has been developed for production of high quality aluminium alloy billets. In the MC-DC casting process, a high shear device is submerged in the sump of the DC mould to provide intensive melt shearing, which in turn, disperses potential nucleating particles, creates a macroscopic melt flow to uniformly distribute the dispersed particles, and maintains a uniform temperature and chemical composition throughout the melt in the sump. Experimental results have demonstrated that, the MC-DC casting process can produce aluminium alloy billets with significantly refined microstructure and reduced cast defects. In this paper, we give an overview of the MC-DC casting process and report on results obtained from an industrial scale trial.
Grain Refinement Efficiency of a New Oxide-Containing Master Alloy for Aluminium Casting Alloys
Authors: Sreekumar Vadakke Madam , Babu Nadendla Hari , Eskin Dmitry G. , Fan Zhong Yun
Published: June 2014

In this study, grain refinement efficiency of a new oxide master alloy based on MgAl2O4 was demonstrated on an A357 alloy. The grain size of the reference alloy was reduced by 50-60% with the addition of the master alloy and introduction of ultrasonic cavitation. A higher addition of master alloy was found to be not benificial in further reducing the grain size.
The Grain Refinement of Al-Si Alloys and the Cause of Si Poisoning: Insights Revealed by the Interdependence Model
Authors: Easton Mark , Prasad Arvind , St. John David H.
Published: June 2014

Recent work has extended the Interdependence Model to the prediction of grain size of aluminium alloys when refined by Al-Ti-B master alloys. The relative contribution of Ti solute and TiB2 particles to the as-cast grain size was determined indicating the optimum level of addition required to provide cost effective use of master alloy. This paper quantifies the effect of Al5Ti1B master alloy additions on the grain size of Al-Si alloys. The Al-Si system is a special case where additions of Si above a few percent poison grain refinement resulting in larger grain sizes. Consideration of the complicating effect of Si poisoning on the prediction of the grain size of these alloys and possible approaches to dealing with these complications are presented.
Effect of Cu on the Microstructure and Mechanical Properties of Diecast Al-Mg2Si-Mg Based Alloy
Authors: Yan Feng , Ji Shouxun , Fan Zhong Yun
Published: June 2014

This paper presents the effect of Cu on the microstructure and mechanical properties of diecast Al-8Mg2Si-6Mg-0.6Mn alloy. The Cu addition in the Al-8Mg2Si-6Mg-0.6Mn alloy can slightly increase the yield strength but decrease the elongation and ultimate tensile strength. Consequently, Cu is considered as a detrimental element in the alloy.
Influence of Microstructural Constituents and Applied Thermomechanical Processes on Corrosion Behaviour of Aluminum Alloys Produced with Twin Roll Casting (TRC) Technique
Authors: Işıksaçan Cemil , Günyüz Mert , Birbaşar Onur , Konya Cengiz , Dündar Murat
Published: June 2014

Aluminum alloys produced with Twin Roll Casting (TRC) technology still necessitate to be thoroughly investigated in some areas. Corrosion mechanisms operating under special conditions with the contribution of unique features of the microstructure are among those. Materials produced with TRC have unique features inherently generated due to the solidification path of the material during casting. Contrary to the very fine particles at the locations close to the free surface, centerline segregation (CLS) occurring at the mid-plane of the thickness have different morphological and compositional features than rest of the microstructure. While, unless directly exposed, it has almost no contribution to the general corrosion behavior of the alloy, some manufacturing processes generation new free surfaces in the material for CLS to be exposed to the corrosive media can be harmful for overall general corrosion performance of the alloy. It differentiates itself in corrosion behaviour with its compositional and morphological features than rest of the microstructure. Hence, influence of CLS on corrosion behaviour of two different alloys in 3000 and 8000 series employed for heat exchangers and packaging applications, respectively, are studied in the present study. Since CLS does not disappear with rolling passes but only changes its morphology, samples were taken at appropriate thickness of the downstream process that allow corrosion tests to be conducted at the cross section of the samples. Metallographical preparation techniques were used to reveal the CLS. Samples were dipped in to the HCl-NaCl containing test solution to observe the progress of corrosion in the matrix and heavily populated CLS areas during the course of test. Open-circuit potential (OCP) measurements were carried out on the rolled free surface, quarter plane and mid plane of the samples after milling the surface of the samples. Different samples produced with compositional and thermomechanical processing route variants were used. Results show that composition of the alloy and applied thermomechanical processes influence the corrosion characteristics of CLS and accordingly the overall corrosion performance. Other important finding is the contribution of manufacturing method to corrosion mechanism whether if it reveals the CLS by creating new free cross sectional surfaces.
Effect of the Microstructure and Environmental Exposure Conditions on the Corrosion Behaviour of the 2050 Alloy
Authors: Guérin Mathilde , Andrieu Eric , Odemer Grégory , Alexis Joel , Blanc Christine
Published: June 2014

Alternate immersion-emersion tests were performed for a 2050 aluminium alloy to characterize its corrosion resistance with exposure conditions representative of in service-conditions. Tests were performed for T34 samples and aged samples. After continuous immersion tests, T34 samples exhibited intergranular corrosion while intragranular corrosion was observed for aged samples. The alternate immersion-emersion tests led to a corrosion extension to the subgrain boundaries, for both T34 and aged samples, as shown by electron backscattered diffraction analysis.
Mechanical Property and Intergranular Corrosion Sensitivity of Al-2.7Cu-1.7Li-0.3Mg Alloy with Small Zn Addition
Authors: Li Jin Feng , Xu Long , Yao Xi , Zheng Zi Qiao
Published: June 2014

The influence of aging (T6 at 150°C and175°C, T8 at 150°C) and 0.72% Zn addition on the mechanical properties, microstructures and intergranular corrosion (IGC) behavior of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. With 0.72% Zn addition, the strength of the Al-Li alloy was increased. As the aging time was extended, the corrosion type of the studied Al-Li alloys was changed in the following order: pitting, local IGC, general IGC, local IGC and pitting again. For the T6 temper, as the aging temperature was elevated from 150°C to 175°C, the aging time period for IGC appearance was shortened. The pre-deformation before aging (T8 temper) also greatly shorten the aging time period for IGC. Meanwhile, the addition of 0.72% Zn decreased the IGC sensitivity and shortened the aging time period for IGC.
The Impact of Machining on the Corrosion Behaviour of AA7150-T651 Aluminium Alloy
Authors: Liu Bing , Zhou Xiao Rong
Published: June 2014

In the present study, the corrosion behaviour of machined AA7150-T651 aluminium alloy has been investigated. It was revealed that a near-surface deformed layer with thickness of 500 nm, characterized by ultrafine grains, is present between the alloy surface and the bulk alloy. In the deformed layer, the MgZn2 precipitates were absent, while segregation bands developed at the grain boundaries. The presence of the segregation bands, rich in magnesium and zinc, promoted localized corrosion in the deformed layer. Potentiodynamic polarization of the alloy in deaerated 3.5 wt. % sodium chloride solution revealed current surges at potentials of-750 mV (SCE) and-670 mV (SCE) respectively. The second current surge was associated with the fast dissolution of the deformed layer. Immersion testing of the alloy in 3.5 wt. % sodium chloride solution showed that the deformed layer acted as anode while the bulk alloy served as cathode during corrosion process.
Improved Accelerated Testing for Localized Corrosion Susceptibility of High-Strength Aluminum Alloys
Authors: Parker Mary E. , Kelly Robert G.
Published: June 2014

Several accelerated tests for high-strength aluminum alloys, such as ASTM G34, ASTM G85 Annex 2, and ASTM G110 can produce significantly different results in third generation aluminum lithium (Al-Li) alloys. In this study, the reason for this inconsistency is investigated by comparing the electrochemical kinetics for AA2060 to those of AA2090 as well as legacy alloy AA7075-T6, and by comparing the performance of AA2060 in ASTM G110 and ASTM G85. The corrosion potential of AA2060 was found to be higher than that of AA7075-T6 and AA2060-T8E41. Also, it was found that although ASTM G110 does not produce exfoliation in AA 2060-T3 as in ASTM G85, the type of attack observed in cross-section is very similar in both tests.
Effect of Stabilizing Treatment on the Intergranular Corrosion Behavior of High Strength Al-Mg Alloys
Authors: Meng Chun Yan , Zhang Di , Cui Hua , Zhang Ji Shan , Zhuang Lin Zhong
Published: June 2014

In order to improve the intergranular corrosion resistance of high strength Al-Mg alloys, the effect of stabilizing treatment was systematically investigated. Microstructure evolutions of Al-Mg alloys after different stabilizing treatments have been studied by scanning electron microscopy and optical microscopy. Mechanical properties and corrosion resistance were measured. It was found that the mass loss of samples after sensitizing treatment decreased with an increase in the stabilizing temperature. It was suggested that the susceptibility to intergranular corrosion for high strength Al-Mg alloys has a strong relation to the stabilizing temperature that modify the morphology and distribution of precipitates. The precipitates continuously precipitated along the grain boundary when the stabilizing temperature was lower than 250°C, corresponding to a poor corrosion resistance. However, the precipitates randomly precipitated in the matrix as globular particles, and discontinuously precipitated at the grain boundary after stabilized at 250°C and 275°C, resulted in an improved intergranular corrosion resistance.
Variation Analysis of Grain Deformation in Aluminum Alloy
Authors: Kobayashi Masakazu , Kawamura Yuki
Published: June 2014

Inhomogeneous deformation in polycrystalline material is interesting matter, because the concentration point of deformation relates with the origins of yield, fracture and recrystallization. Plastic strains in three-dimension during tensile deformation have been investigated by using the marker tracking method in synchrotron X-ray microtomography. Three-dimensional position of grains was detected by grain-boundaries visualizing method. The variation of deformation were measured for each grain. We summarized how much degree grains was deformed inhomogeneously comparable to the plastic deformation in whole specimen.
Analysis of Small Fatigue Crack in Al-Mg-Si Aluminum Alloy
Authors: Shikama Takahiro , Yoshihara Shinji , Takahashi Yoshimasa , Noguchi Hiroshi
Published: June 2014

In general, aluminum alloy does not exhibit distinct fatigue limit (knee point) in the S-N diagram. The growth of a small fatigue crack of precipitation-hardened Al-Mg-Si system alloy (6061-T6) was investigated to clarify the mechanism of non-appearance of distinct fatigue limit (knee point) in the S-N diagram. The small crack was analysed in detail by replica method, scanning electron microscope (SEM), and Electron Back Scatter Diffraction Patterns (EBSD). On the other hand, the existence of distinct fatigue limit (knee point) of new developed aluminum alloy by adding excess Mg to the 6061 alloy was found. In this study, the resistance of small crack growth of the developed alloy was compared with standard 6061 alloy. It was revealed that the resistance of crack growth of new developed alloy was higher than that of standard 6061 alloy in short crack region (l<1.0 mm).
Modeling of the Influence of Pore Morphology on Damage Behavior of an Aluminum Die Casting Alloy
Authors: Sun Dong Zhi , Ma Ying Song , Andrieux Florence
Published: June 2014

The analysis of deformation and damage behavior of aluminum cast components is very complex, since local mechanical properties in the components are inhomogeneous as a consequence of spatial distribution of microstructure e.g. pore size, grain size and arm spacing of secondary dendrites. Moreover, the damage behavior of aluminum alloys depends strongly on stress state. Until now it is not clear how the pore morphology affects the damage behavior under different loading situations. In this work the damage behavior of the aluminum die casting alloy AlSi9Mn was characterized with tension specimens extracted from different positions in a component. Damage effect was modeled with representative volume elements (RVE) with variation of porosity, pore size and distribution of pores under uniaxial and biaxial tension, plane strain, compression and shear. Not only pore growth and coalescence but also damage of the matrix material was taken into account in the simulations. A large influence of pore morphology on fracture strain was found and relationships between fracture strain and pore morphology were proposed for different stress states.
Effect of Rolling on Mechanical Properties and Fatigue Behavior of an Al-Mg-Sc-Zr Alloy
Authors: Zhemchuzhnikova Daria , Kaibyshev Rustam
Published: June 2014

An aluminum alloy with a chemical composition of Al–6%Mg–0.35%Mn–0.2%Sc–0.08%Zr–0.07%Cr (in wt.) was rolled up to different reductions of 75, 88 and 95% at 360oC and at ambient temperature. The static mechanical properties and the high-cyclic fatigue (HCF) life were examined. It was shown that the hot rolling results in increased yield stress (YS) and ultimate tensile strength (UTS). However, ductility and fatigue limit of the hot rolled alloy and initial as-cast ingot are nearly the same. The combination of hot and cold rolling leads to significant improvement of tensile strength and fatigue resistance, while ductility tends to reduce with increasing the rolling reduction. The cold rolled alloy exhibits the endurance limit under fatigue conditions, while the alloy in the both as-cast and hot rolled conditions exhibits only fatigue strength. The effect of the deformation structure on the mechanical properties is discussed.
Dissimilar-Metal Joining Using Several Types of High-Speed Solid-State Welding Methods
Authors: Kumai Shinji
Published: June 2014

Solid-state welding is useful to join dissimilar metal couples, in particular, with a large difference in physical and mechanical properties. However, conventional solid-state welding methods such as diffusion welding and roll bonding are not necessarily applicable to all metal combinations. In addition, they are time-consuming. In the present study, various dissimilar metal joints (e.g. Al/Fe, Al/Cu, Al/Ni, A2024/A5052, A6022/steel, A6022/Plated steel, A2024/AZ80) were fabricated by using several types of high-speed solid-state welding methods; friction stir spot welding, advanced stud welding and impact welding. The strength and characteristic interfacial morphology of the joints were investigated, and each joining mechanism is discussed. In particular, for the impact welding, both experimental and numerical analyses were performed. Two metal sheets were obliquely collided at a very high speed and joined by magnetic pressure or explosive force. Smoothed Particle Hydrodynamics (SPH) method was used to simulate the impact welding process. The emission of metal jet and the evolution of characteristic wavy interface at the joint interface could be clearly visualized. The effects of collision angle, collision velocity and difference in density of the metals on the wave morphology were revealed.
Effect of Intermetallic Compounds Content on Laser Welding Performance of Al-Fe Alloy Sheets
Authors: Zhao Pi Zhi , Pan Yan Feng , Tao Jiang , Shi Xiang Jun , Zhang Qi
Published: June 2014

The present study investigated the laser welding performance of Al-Fe aluminum alloy sheets with different contents of intermetallic compounds. Under the same welding parameters, the alloy of higher intermetallic compounds content has wide and deep weld pools with uniform sizes. The alloy of lower intermetallic compounds content has narrow and shallow weld pools with nonuniform sizes. The higher content of intermetallic compounds results in higher laser absorptivity and lower thermal conductivity, and then increases the effective absorbed energy during welding, which is beneficial to the formation of wide and deep weld pools. The distribution uniformity of intermetallic compounds influences the size uniformity of weld pools. In the alloy with lower content of intermetallic compounds, the nonuniform distribution of intermeallic compounds results in the formation of abnormal weld pool, leading to the nonuniform size of the weld pools. In the alloy with higher content of intermetallic compounds, uniform distribution of intermetallic compounds make the size of weld pools more uniform.
Three Point Bend Performance of Solutionized, Die Quenched and Heat Treated AA7075 Beam Members
Authors: Bardelcik Alexander , Bouhier Alexandre , Worswick Michael J.
Published: June 2014

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.