Aluminium Alloys

Laser welding will be  an important welding process for different applications in aerospace , aircraft , automotive, electronics  and other industries, due to its capabilities like minimum heat affected zone, welding of various thicknesses, adoptability to welding of various materials possessing widely varying physical properties like melting point, absorption, reflectivity etc. It utilizes laser source as a non contact heat generation technology to weld different materials so as to achieve welds of high quality narrow width and high penetration depths without the need of filler wires. It may be necessary to understand the effect of process parameters on the weldability of materials for successful welding. Laser welding popularly uses two types of lasers like CO2 and Nd:YAG (neodymium doped yttrium – aluminium – garnet)  with different powers. Nd:YAG lasers are used to weld materials of different thicknesses involving powers upto 5 kW. Whereas, CO2 lasers are used for applications which involve higher powers upto 20 kW. Laser welding allows a direct transition from light energy into heat energy. This technique is involved with the process of laser - matter interaction in which various parameters such as pulse energy, pulse duration, spot size, welding speed, laser power, weld width, penetration depth, reflectivity, absorption coefficient, thermodynamic properties etc. are used for analysis. This paper presents a review of the different parameters including process as well as materials on the weldability of various materials like carbon steels, stainless steels, magnesium alloys, aluminium alloys, refractory materials such as vanadium, titanium, zirconium, tantalum etc. The selection of appropriate parameter for welding of specified material is discussed. The prominent weld defects common to the laser welding such as porosity, oxide inclusions, cracking, loss of alloying elements etc., are discussed as related to the microstructure as well as mechanical properties such as hardness, tensile strength and fatigue strength etc.

Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of ...

A dislocation density-based crystalline plasticity formulation, specialized finite-element techniques, and rational crystallographic orientation relations were used to predict and characterize the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary distributions. Different layer arrangements were investigated for high strain rate applications and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-bonded interface and the potential delamination of the layers. Shear strain localization, dynamic cracking, and delamination are the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be used to optimize behavior for high strain rate applications.

Friction stir welding (FSW) is the fastest evolving joining technology and the principal
prospective technique for implementing integral fuselage structure in aircraft manufacturing.
The viability of FS welds is dependent upon mechanical properties and production turnovers,
which are dependent on welding rates and tool design. This dissertation is about the multiobjective
characterisation of aeronautical alloys (AA5083-H111, AA6056-T4, AA6082-
H111) friction stir welded using the standard FSW tools, scrolled shoulder Triflat tool, and
the Bobbin tool respectively.
The effects of defects and microstructure on the mechanical behaviour of AA5083-H111
welds made from the standard tool were examined. SEM analysis showed that tunnel defects
resulted from partial consolidation at the root of the weld, and the microstructure of the weld
zones determined the failure mechanisms along the weld.
The effect of welding and rotational speeds on the integrity of AA6056-T4 FS welds
produced with scrolled shoulder Triflat tool was studied. Increased welding speeds and
advance per revolution led to improvements in mechanical properties and reduction in
residual stresses maxima. The retreating side TMAZ, which was the microhardness minimum
and tensile residual stress maximum, was also the failure location in most of the welds, hence
the microstructure and properties in this region were critical to the integrity of the weld. Bend
properties of the welds from the Triflat tool were good, because of the absence of root flaws.
The influence of two different tool designs (standard tool and standard Bobbin tool) on
mechanical behaviour and microstructure of AA6082-T6 was also studied. The standard tool
produced welds with better static properties than the bobbin tool, but most of the specimens
failed prematurely, and root bending resulted in cracks, because of alumina rich layers in the
weld nugget and root flaws. Bobbin tool welds had lower mechanical properties (70% weld
efficiency), the bend strength was better, with no flaws.
In the welds, the microstructure and microhardness which were influenced by the welding
rates which determined static properties, failure locations and residual stress minima and
maxima. The study also supported previous findings that the nature and distribution of
precipitates in the 6XXX series aluminium FS welds was important for determining
mechanical properties, unlike the 5083-H111 FS welds where the Hall-Petch effect was more
influential.

The brake system is an important part of an automobile. It plays a vital role in helping the driver to reduce the speed of an automobile or to stop the automobile. Initially, when automobiles were first introduced, they were equipped with drum brakes. These drum brakes were cheap, easy to install and atmospheric agents cannot hinder their performance. Despite these advantages, the major disadvantage of the drum brake system is the poor heat dissipation. To tackle this problem, the automotive engineers came up with the disc brake system. The brake rotor is one of the most critical components of the disc brake system. The brake rotor is made up of a pure metal or a metal with certain reinforcements. These brake rotors are circular with perforations made in a particular manner to enable faster dissipation. These perforations help to reduce the weight of the disc brake rotor. The disc brake rotor is fixed to the wheel hub with brake calipers. In this review article, I will be critically analyzing various research articles on the thermal and mechanical properties of various brake rotor materials used in automobiles.

"A target of Fe-40 at.-%Al intermetallic alloy with ordered B2 structure was subjected to laser melting processing by a high energy XeCI excimer pulse (wavelength 308 nm, pulse length 120  ns) in low pressure air. The total thickness of the laser affected zone (LAZ) was ∼ 150 nm. The modified surface showed an increased roughness and the presence of cracking. The X-ray photoelectron spectroscopy (XPS) measurements revealed a strong enrichment in the aluminium concentration within the LAZ, as well as relatively high contents of oxygen and nitrogen incorporated in the near surface region. Both angle resolved and depth profile XPS analyses suggested that oxides, nitrides, and oxynitrides were mainly present within the LAZ as discrete particles in the metallic matrix rather than as surface layers. Significant surface hardness reduction was observed after laser treatment, which has been interpreted to be due to partial suppression of B2 lattice ordering. Electrochemical measurements  in borate buffer solution showed a reduced anodic activity of the laser processed aluminide in the potential range between the open circuit potential and 0.1 V saturated calomel electrode, whereas at higher anodic overpotentials no substantial differences in behaviour were observed with respect to the untreated Fe–40Al surfaces. Such consequences of the excimer laser treatment may be explained by mechanisms involving aluminium enrichment and nitride formation processes inside the LAZ."

New materials and production technologies demand improved non-destructive techniques for inspection and defect evaluation, especially when critical safety applications are involved. In this paper two Non-destructive Testing (NDT) applications are presented: the inspection of Friction Spot Welding (FSpW) of AA2024-T351 with and without Alclad™ and a composite material GLAss-REinforced Fibre Metal Laminate (GLARE®) with artificial defects. The two applications were tested by Eddy Currents (EC), using both conventional planar spiral probes and a new EC probe developed by some of the authors, called lOnic probe. Four different FSpW conditions were produced and tested in 2 mm-thick plates of duraluminium with and without Alclad™. Three defects were introduced in GLARE® aiming to compare the reliability of the different NDT approaches. The experimental results show that the lOnic probe is able to identify different levels of FSpW quality regions by a distinctive perturbation on the output signal, whereas conventional probe cannot distinguish the different FSpW conditions. Regarding the GLARE® application, it was found that lOnic probe can detect the deeper defect easier than the conventional EC probe.

Micromechanical models used to predict mechanical and fracture properties of brittle metallic foams are validated experimentally for closed-cell aluminium foam (AlSi12Mg0.6) prepared by powder metallurgy route. Compression, tensile, tensile on notched specimens and fracture toughness tests were carried on, and the results are presented together with micromechanical models from literature. Moreover, the Digital Image Correlation technique was applied to identify the failure mechanisms of aluminium foams. Finally, the Theory of Critical Distances was employed to predict the fracture load of notched specimens. The novelty of the study is that the inherent stresses and critical distances were obtained by employing micromechanical analysis.

In this paper, we conduct a friction stir welding lap joint experiment on Al-Mg-Si alloy to investigate its formation and mechanical properties. By studying and observing the surface morphology, it was discovered that the higher the welding speed, the lower the burst and flash effect. In the cross-sectional analysis, we obtain larger EST (1.59) at rotating speed (1600 rpm), welding speed (150 mm/min) and 0.15 mm depression, and a nearly identical EST (1.58) at rotating speed (1200 rpm), welding speed (100 mm/min) and 0.15 mm depression. We talked about welding speed and other working parameters, and we found that rotating speed (1600 rpm) and welding speed (150 mm/min) with the more practical tensile shear load (10.11) produced significant results. In the Microhardness section, it was discovered that increasing the mixing head's rotational speed increases the heat input, resulting in a higher nucleation number of recrystallized grains and we obtain the best microhardness of the curve at rotating speed (1400 rpm), welding speed (150 mm/min) and 0.1 mm depression. The higher heat input (1600-150-0.15) along the fracture path results in a better metallurgical bonding effect of the cold lap, and the fracture propagates downward from the highest point of the cold lap to the lower sheet under the smaller EST.
Key Words: FSW; Tool Rotation Speed; EST; Microhardness; Fracture Path

The viscoelastic response of commercial Al–Zn–Mg and Al–Cu–Mg alloys was measured with a dynamic-mechanical analyzer (DMA) as a function of the temperature (from 30 to 425°C) and the loading frequency (from 0.01 to 150 Hz). The time-temperature superposition (TTS) principle has proven to be useful in studying mechanical relaxations and obtaining master curves for amorphous materials. In this work, the TTS principle is applied to the measured viscoelastic data (i.e., the storage and loss moduli) to obtain the corresponding master curves and to analyze the mechanical relaxations responsible for the viscoelastic behavior of the studied alloys. For the storage modulus it was possible to identify a master curve for a low-temperature region (from room temperature to 150°C) and, for the storage and loss moduli, another master curve for a high-temperature region (from 320 to 375°C). These temperature regions are coincidental with the stable intervals where no phase transformations occur. Th...

The paper provides an overview of tribological properties of nanocomposites with aluminium matrix. Nanocomposites represent a new generation of composite materials with better properties than conventional composite materials. The paper presents and explains the most common methods of nanocomposites production. In addition, the overview of tribological properties is presented through the equipment used for testing; amount, size and type of reinforcement; matrix material and manufacturing process; and test conditions. ARTICLE HISTORY Received 15 August 2016 Accepted 3 September 2016 Available online 30 September 2016

As part of a current project on through process modelling (TPM) of welded aluminium structures, experimental studies have been carried out on butt-welded specimens of aluminium alloy AA6060 and AA7046. Two tempers; T4 and T6 prior to welding were investigated and the subsequent effects
of natural ageing (NA) and post weld heat treatment (PWHT) were assessed. Cross-weld tensile tests were carried out with digital image correlation (DIC) to determine the strain field. Variations of the mechanical properties of the material in the vicinity of the weld were also studied by hardness
measurements. The experimental results are presented in terms of response curves and hardness measurements. These data will subsequently be used for verification and further development of microstructure based models for predicting the distribution of mechanical properties in the heat affected zone (HAZ) based on coupling to a thermal model. Through further coupling with a non-linear mechanical model, high precision finite element (FE) simulation of welded aluminium structures is sought.

Fatigue plays a significant role in the crack growth of the fuselage skin structures. In addition, the fuselage may suffer also from the corrosion damage, and the wear defects. The proper maintenance and scheduled test intervals can avoid the sudden skin failure. Therefore, the inspection interval has to be shortened. Nevertheless, the young machines may be also suffering from the unexpected skin rupture. The cracks are emanating from the rivets and the holes under cyclic loading. The stress concentration around the notch has an effective role under the effect of cyclic loading. The cracks propagate toward the high stressed area such as the notches or other crack locations. The propagation into a critical crack size is rather fast and causes a sudden aircraft fuselage cracking. Hence, the number of cycles to failure will be decreased dramatically. During the last decades, the fracture toughness, design, and the new alloying element have been enhanced. The previous fuselage failures show that the inspections against the cracking are recommended even after a few thousand of cycles. To prevent the crack extending, the crack arresting is recommended to use around the fuselage.

The fatigue resistance of an aluminium alloy used for casting engine blocks was studied. The tests were carried out with specimens machined from the bulkheads of V8 engine blocks cast by the low pressure process. The samples were obtained from two different locations in the bulkheads to evaluate the effect of microstructural refining as the material was cut from regions in which the secondary dendrite arm spacing was within two different sizes, namely 30 and 45 lm. The samples were tested either in their as-cast and heat treating conditions in a computer controlled servohydraulic machine. The tests were fully reversible following staircase schedules. The specimens were fatigued to fracture or up to 107 cycles.
The results show that fatigue cracks nucleate in pores located close to the surface of the specimen. It is concluded that the fatigue resistance is affected by heat treating and microstructural refining. The enhancement in fatigue resistance due to microstructural refining is documented. An analysis was carried out to predict the cycles to failure that the material is able to sustain.

Aluminium was a vital raw material during the Second World War, as it was used in numerous assets that were fundamental to the new military strategy of aerial warfare. The United Kingdom’s war machine depended heavily on it for the manufacture and repair of aircraft, and as a core component in incendiaries, high explosives, and “Window” foil. Fundamentally, aluminium can be used over and over again without loss of properties. From 1940 to 1944, a third of the UK’s total requirements of aluminium and aluminium alloys were met by secondary material, without which another 100,000 tons of virgin ingot would have had to be imported from North America per year. The technique of scrap aluminium segregation and utilisation developed during this period produced ingot which in the first grade was of equal value and used as virgin material. Crucially, scrap was already in the UK, and thus provided its war machine with thousands of tons of additional virgin and secondary aluminium at a time when it faced uncertainty over aluminium imports from across the dangerous North Atlantic. All this suggests that the natural resource of aluminium, in its secondary form of scrap, was fundamental to Britain’s war effort: it was a vital component in tools of war, and it was already present in the country. Recycling remains a major aspect of continued aluminium use, with more than a third of all the aluminium currently produced globally originating from new, traded, and old scrap.

The growing demand for chromium coated aluminium components especially for the automotive industry is due to their favourable physical properties (density, strength to weight ratio etc.). However, their frequent use under harsh environmental conditions renders them corrosion sensitive and consequently they need to be protected. An approach that has been applied in industry is to directly electroplate nickel onto aluminium substrate prior to a top metallic finish; however, in components with complex geometry, certain areas could become exposed to corrosion attack due to poor surface coverage during plating. In this study, a modified electroless nickel undercoat was applied to pre-treated aluminium alloys prior to duplex nickel and chromium plating with a view to enhance corrosion resistance, improve coating adherence and durability, and overall, to achieve substrate protection. Hexavalent and trivalent chromium were applied to pre-treated Al 1050 and Al 6061 following electroless nickel deposition, and plating performance was assessed by surface and corrosion techniques, while durability was measured by scratch, adhesion and hardness tests. Overall, while chromium plating with an electroless nickel undercoat did not improve corrosion resistance or hardness of the materials, it provided an additional protective layer for the substrate with a potential for longer term durability.

In this study, a study on welding aluminum weldings with techniques such as TIG welding, MIG welding, Friction Stir welding, Laser Beam welding is compiled. Problems such as porosity, weld seam cracks and unstable arc that may occur as a result of the mentioned welding techniques have been investigated. The main purpose of this study is to examine the weldability of aluminum alloys and the causes and solutions of damage during or after welding. Apart from this purpose, information about the welding of aluminum alloys with other materials can be obtained. The effects of welding parameters on obtaining smooth welding products are mentioned. At the same time, the effect of the internal structure and chemical components of the alloys used on the welding process is not ignored.

In this study, EN AW 6082 Al alloy was used as expermental material due to producing in car suspension systems. The microstructure and mechanical properties of the alloy in aging and extreme aging conditions were compared with extrusion and extrusion + hardness values. The samples were subject to T6 heat treatment extracted from extruded and extruded and forged EN AW 6082 alloy parts to give 85 HB hardness. The second group was reduced to peak hardness and then to 85 HB hardness by over-aging. tensile and notch impact tests were applied to characterize the mechanical properties of the both samples. Microstructure characterization was also performed by optical microscope. Fracture surfaces of the samples were also examined by SEM after tensile tests. Özet Bu çalışmada, otomobil süspansiyon sistemlerinin rotilli kol imalatında kullanılan EN AW 6082 alüminyum alaşımının ekstrüzyon ve ekstrüzyon+dövme sonrası aynı sertlik değerlerini veren yaşlandırma ve aşırı yaşlandırma kondisyonlarındaki mikro yapı ve mekanik özellikleri karşılaştırılmıştır. Çalışmada, ekstrüde edilmiş ve ekstrüde edilip dövülmüş EN AW 6082 alaşımı parçalarından çıkartılan numunelere T6 ısıl işlemi uygulanarak 85 HB sertlik kazandırılmıştır. İkinci grup numuneye de aşırı yaşlandırma yapılarak pik sertliğe ve ardından tekrar 85 HB sertliğe düşürülmüştür. Her iki grup numuneye de çekme ve çentik darbe testleri uygulanmıştır. Mikro yapı karakterizasyonu da optik mikroskop ile gerçekleştirilmiştir. Çalışmada ayrıca çekme testleri sonrası kırık yüzeyler SEM ile incelenmiştir.

Friction-stir welding (FSW)is a novel green solid state joining process particularly used to join high strength aerospace aluminum alloys which are otherwise difficult to weld by conventional fusion welding. Unlike other solid state joining technique, in Friction stir welding a third body contact by tool will generate the additional interface surfaces and finally all the surfaces are coalesced with each other by applied pressure and temperature and form solid state weld. This work shows overview of Friction stir welding which includes the basic concept of the process, microstructure formation, influencing process parameters, typical defects in FSW process and some recent applications. In this project, FEA analysis is performed for friction stir welding of different aluminum alloys. The welds are produced by varying the process parameters; the rotational speed was varied between 900 to 1800 rpm and the welding speed varied between 40 and 300mm/min. A parametric model with the weld plates and cutting tool is done in ProE. The effects of different (square and round) tool pin profiles on the friction stir welding are also considered for analysis. Different tool pin profiles are square, circular square with thread. We are using Vertical milling machine for doing welds. And also we are doing Tensile testing, Hardness and Microscopy for Structure at welding spots. Modeling is done in proe software and analysis is done in Ansys. The best parameters found from the experiments are 1800 rpm square is better for welding using HSS tool.

Based on the theory of Damage Mechanics, the damage of material is considered as an internal state variable. It describes the deterioration of material upon loading. If it is locally defined, then, the damage of a material point is completely determined by the state of its own. It is also known as local material damage model, a popular way in current modeling of material damage. On the other hand, the nonlocal damage model provides an alternative way to define the material damage of a point through certain domain on where it lays. This approach yields a more accurate stress description than that of the local model in describing high stress/damage gradient structures, such as an observed crack in a structure.

To describe the damage characteristics in high stress/damage gradient structures, a nonlocal damage model is developed in this work. The nonlocal damage is treated as weighting average over a prescribed domain in terms of explicitly expressed damage gradient. The proposed damage model together with the constitutive model of aluminum alloy are implemented in a commercial finite element code ABAQUS (Version 6.5) via its UMAT subroutine. Full implicit integration scheme is used to solve for internal variables of integration point (IP) at each time interval. Then the weighting average is carried out over a particular domain characterized by Characteristic Length for the processing IP. Finally, consistent tangent modulus (Jacobian) of this IP is provided to ABAQUS to assemble global stiffness matrix. A center- cracked specimen made of AL2024-T3 is chosen as a typical example to illustrate the advantage of introducing nonlocal damage and also to provide a validation of the proposed constitutive model. In addition, the effects of Characteristic Length and strain-hardening coefficient on the proposed nonlocal model are investigated and discussed.

One major consideration on the development of the nonlocal damage model is the stress/damage gradient observed in a loaded structure. As illustrated in chapter 2, there is no difference in the computed stress/damage distribution based on the nonlocal damage model and corresponding local ones in a homogeneous structure where no gradient exists when loaded. To examine the effect of stress/damage gradient on structures, notches of varying radii are designed to examine notch sensitivity on the nonlocal model.

Unlike a typical strain hardening material of AL2024-T3, 63Sn37Pb exhibits strain-softening behavior. The proposed nonlocal damage model is coupled into the constitutive model of 63Sn37Pb to show its applicability on strain softening materials. Again, the nonlocal damage model together with the constitutive model of 63Sn37Pb is incorporated into ABAQUS via its UMAT subroutine. Similar to the strain hardening material AL2024-T3, the mesh-sensitivity is remarkably reduced, demonstrating that the proposed nonlocal damage model is capable of being applied to both strain hardening materials and strain softening ones.

Recrystallization has an important effect in the production of aluminium alloys. The control of microstructure
and texture during recrystallization have major economic importance. Since recrystallization consists of
formation of new defect free grains, it is very important for industrial applications. This paper explain the
concept of recrystallisation, state the driving force for recrystallisation, outline the microstructural changes that
take place during recrystallisation, state the factors which affect recrystallisation rate, state the laws of
recrystallisation and differentiate between recovery and recrystallisation.

In this era of mass manufacturing MRR (material removal rate) is of prime concern even in manufacturing using CNC machines. The main objective of today's modern manufacturing industries is to produce low cost and high quality product in short time. In order to improve the quality and to reduce the cost material removal rate should be optimum. In machining accurate dimensions is desired but with good product quality. Machining process involves many factors which affects the process directly or indirectly. The research study aims to analyze MRR by taking feed, depth of cut &spindle speed into consideration of Aluminum 6063 employing Taguchi method. A L9 Orthogonal array is used to performing the various experimental studies that analysis the MMR and analysis of surface roughness and signal to Noise Ratio (S/N ratio).

The effect of zinc and tin addition to pure aluminum was investigated in 3 wt.% NaCl solution. The corrosion behavior of the elaborated samples (Al, Al–Zn and Al–Zn–Sn) was studied by open circuit potential, Tafel plot and electrochemical impedance spectroscopy. For the microstructure characterization, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy were used. The aluminum activation increases in the following order: Al < Al–5Zn < Al–5Zn–0.1Sn < Al–5Zn–0.2Sn < Al–5Zn–0.4Sn. The impedance measurements and the microscopic observations confirmed the great activity of Al–Zn and Al–Zn–Sn compared to pure Al. The segregation at the grain boundaries leads to intergranular corrosion.

Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of AFO must ensure compactness, light weight, low noise, and high efficiency. These entailments present significant engineering challenges to develop a new design with wide consumer adoption. © 2014 Morshed Alam et al.

http://www.ncbi.nlm.nih.gov/pubmed/24892102 
http://www.hindawi.com/journals/tswj/2014/867869/abs/

The partial and integral enthalpies of mixing in liquid Al-Si and Al-Cu alloys were determined by high-temperature isoperibolic calorimetry at 1750±5 and 1590±5, respectively. The thermodynamic properties of Al-Si melts were also studied by the electromotive force method in the temperature range 950-1270 K. The partial and integral excess Gibbs free energies of mixing in liquid Al-Si and Al-Cu alloys were calculated from literature data on the thermodynamic activity of aluminum. The comparison of our experimental results with literature data has been performed.

aqueous reaction to form the hydrated fluorides which are subsequently dehydrated at elevated temperatures in an atmosphere of HF gas. Extensive studies were made of the conditions for the preparation of high-purity ZrF4, and pilot plant equipment is described which was used to prepare 100 lb batches of the fluorides. The reduction step was investigated thoroughly, particularly for Zr, and those factors which affect metal quality and yield were determined. Reduction yields of 96 % were obtained with both Zr and Hf. After are-melting, the sponge Zr had a hardness of 40-45 Rockwell A and was readily cold-rolled into sheet. Zr metal thus prepared had a purity of about 99.8%. Hf metal, similarly prepared, had a hardness of 69 Rockwell A and was hot-rolled but was too brittle to be easily cold worked. The Hf was low in metallic impurities, but contained considerable amounts of C, N, and oxygen. ACXNOWLI~DGMENTS The authors are especially grateful to J. W. Starbuek for his valuable contribution in the experimental redue-tion studies, to B. A. LaMont and co-workers for the chemical analyses, and to C. Lentz and associates for the spectrographic analyses. ABSTRACT At low overvoltage values, deviations from Tafel behavior for a noncorroding electrode are due primarily to the reverse reaction of the oxidation-reduction system, and at high overvoltages to concentration and/or resistance polarization. It is shown further that the practice of placing straight lines through a few experimental points is extremely hazardous, while the indiscriminate introduction of "breaks" is contrary to the electrode kinetics described. Further complexities arising from a corroding electrode are described. In this instance , the forward and reverse reactions of both of the oxidation-reduction systems forming the corrosion couple must be considered. This representation of the local polarization diagram of a corroding metal is more fundamental than that used previously in the literature, and thus provides a clearer picture of the various factors which affect the corrosion rate and the shape of polarization curves. A region of linear dependence of potential on applied current is described for a corroding electrode by treating it in a manner analogous to that for a noncorroding electrode. An equation is derived relating the slope of this linear region to the corrosion rate and Tafel slopes. This relation provides an important new experimental approach to the study of the electrochemistry of corroding metals since, in some instances, interfering reactions prevent determination of T~fel slopes at higher current densities. Polarization measurements are an important research tool in investigations of a variety of electrochemical phenomena. Such measurements pernfit studies of the reaction mechanism and the kinetics of corrosion phenomena and metal deposition. In spite of their wide applicability and extensive use, considerable uncertainty in the interpretation of polarization measurements still exists. Some of the uncertainties include the proper method of plotting data and the correct interpretation of "breaks" in polarization curves. Abrupt changes in slope of overvoltage vs. log current have been given considerable significance in the past few years. Logan (1) examined various methods of plotting cathodic polarization measurements to evaluate the correspondence between current required for complete cathodic protection of a system and current flow at the potential break. He reported that the potential break) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.88.117.172 Downloaded on 2016-01-28 to IP

Tangki BBM: Dimensi Tera tangki adalah merupakan jumlah nilai batas hitungan cairan yang ditentukan berdasarkan hasil pengukuran dari Badan Metrologi. Untuk mendapatkan nilai kapasitas tangki bbm, Metrologi menggunakan beberapa alat bantu ukur. Alat bantu ukurnya memakai tongkat ukur yang biasa disebut mistar ukur atau deepstik. Bejana ukur berkapasitas seribu liter (1 ton; relatif) berbentuk seperti panci besar yang di bawahnya diberi kran tempat keluarnya cairan. Bejana ukur 10/20 liter, Waterpass dan Salib ukur.

MIG, the welding process which can be applied for many kind of materials, was used on 6XXX series of aluminum to perform a joining to be able to investigate hardships and trials of MIG welding on aluminum type of metal when it’s used instead of TIG process for nonspecific applications. Because when it’s preferred instead of TIG, one of the major issues with MIG process for aluminum is implementation part( Handicraft requirements etc). No attention on purpose paid to surface cleaning. Different welding techniques have been used on this case and the sample has been examined by optical microscope, SEM, EDX and hardness test. As the results of the tests, first of all, it was shown that MIG is trickier method than TIG throughout implementation of welding. Not to pay attention to surface cleaning caused dendritic structures which were located as small clusters on the surface due to the NaCl droplets which were identified by EDX chemical composition analysis. Also, SEM analysis rendered possible to determine dendritic structures, inclusions which we couldn't have determined without SEM, and there was a chance to examine hardness of a metal part which had been produced by mechanical extrusion method. Different hardness values were obtained on the parent material because of extrusion. In the fusion zone of the material, as expected there was decrease of hardness because of incidents which occurred during heating and cooling cycles.

This is a study on grain-scale micromechanics of polycrystal surfaces during plastic straining. We use Al–Mg–Si sheets (alloy AA6022) as model material. The work aims at understanding the relationship between microstrain heterogeneity and surface roughness in plastically strained polycrystals in terms of the surface and through-thickness microstructure. Experiments were conducted on polycrystals with identical composition but different processing and microstructures. We performed tensile and bending tests on sheet samples cut in transverse and rolling directions. We investigated the plastic surface microstrains (photogrametry), surface topography (confocal microscopy), particle distribution (metallography, SEM), microtexture (EBSD), and grain size distribution (EBSD) in the same sample regions.
We also conducted in-situ straining experiments where the microtexture, surface topography, and stress–strain behavior
were simultaneously determined. The results reveal a relationship between the heterogeneity of plastic surface microstrains, roughness, and microstructure. In particular a correlation could be established between microstrains and banded microtexture components (Cube, Goss, {111}[uvw]).

Welding is a widely used process in industry because welding techniques have some striking features which are included in this project. In other way of saying, welding techniques will be so important in human life in the future because of their unique specialties. For this reason, researches and studies on welding are increasing day by day.
Welding is used in different areas in industry and it has various features. Welding is especially used in the manifacturing area, as a connector between materials in the existence of heat and pressure (with or without additional materials). The main targets in this process are; lowest cost, highest satisfaction in performance and longest life.
In this project, the importance of choosing a suitable production regarding to the intended features and how to improve the mechanical features, tried to be explained. Therefore, the welding process which is going to be applied to the materials which has different metal content, are virtually modelled by using Ansys Workbench software.
Parameters as, used materials and chosen welding techniques within this project are widely explained.  Experimental studies were done in order to help the project to enlighten the future studies and to make the project based on numerical data (simplifies prooving). In the other parts of the experimental studies, welding process is applied to the materials which have different metal contents by using Ansys Workbench software. Modelling a material using different welding techniques before production gives  more practical and more proactive vision.

There are several facets of aluminum when it comes to sustainability. While it helps to save
fuel due to its low density, producing it from ores is very energy-intensive. Recycling it shifts
the balance towards higher sustainability, because the energy needed to melt aluminum from
scrap is only about 5% of that consumed in ore reduction. The amount of aluminum available
for recycling is estimated to double by 2050. This offers an opportunity to bring the
metallurgical sector closer to a circular economy. A challenge is that large amounts of scrap
are post-consumer scrap, containing high levels of elemental contamination. This has to be
taken into account in more sustainable alloy design strategies. A “green aluminum” trend has
already triggered a new trading platform for low-carbon aluminum at the London Metal
Exchange (2020). The trend may lead to limits on the use of less-sustainable materials in
future products. The shift from primary synthesis (ore reduction) to secondary synthesis
(scrap melting) requires to gain better understanding of how multiple scrap-related
contaminant elements act on aluminum alloys and how future alloys can be designed upfront
to become scrap-compatible and composition-tolerant. The paper therefore discusses the
influence of scrap-related impurities on the thermodynamics and kinetics of precipitation
reactions and their mechanical and electrochemical effects; impurity effects on precipitationfree
zones around grain boundaries; their effects on casting microstructures; and the
possibilities presented by adjusting processing parameters and the associated mechanical,
functional and chemical properties. The objective is to foster the design and production of
aluminum alloys with the highest possible scrap fractions, using even low-quality scrap and
scrap types which match only a few target alloys when recycled.