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Welding
Kinds of Welding Terms modified by Welding Selected AbstractsSimulation of Welding and Distortion in Ship Building,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Thomas Rieger Simulation tools will continue to gain importance for both scientific investigations and industrial applications. This further applies to welding technology. The present work focuses on the simulation of distortions due to the welding of stiffeners on heavy plates in shipbuilding. An equivalent heat source (EHS) was computed by the software SimWeld to describe the energy input caused by welding. The EHS was combined with an FEM simulation of the global structure in the commercial program SYSWELD. Therefore an interface between the SimWeld platform and SYSWELD was implemented. The simulation results were compared with a welded demonstrator. The predicted displacements correlate closely with the experimental data. Using the combined approach the quality of the prediction was significantly improved against the typical method of heat source parameter identification, which is based on experimental results. The results allow for the optimization of welding sequences and for the minimization of buckling in shipbuilding. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Mater. The Cover shows a hybrid joint for multi-material lightweight components realized by ultrasonic metal welding at the Institute of Materials Science and Engineering at the University of Kaiserslautern. Ultrasonic welding is one innovative technology for joining carbon fibre reinforced polymers (CFRP) with sheet metals like aluminium alloys or aluminium plated steels. The achievable mechanical properties of the ultrasonic welded joints were carried out by using statistical test methods. One example for the evaluation of the welding results is presented on the left hand side of the Cover. Additionally a scanning electron micrograph of the bonding zone of an aluminium/CFRP-joint is shown in the background. More details about the ultrasonic welding technique can be found in the article of F. Balle, G. Wagner and D. Eifler on page 35 of this issue. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Frank Balle The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. The investigations described in this paper were carried out using the ultrasonic metal welding technique for joining carbon fibre reinforced thermoplastic composites (CFRP) with sheet metals like aluminium alloys or aluminium-plated steels. The achievable mechanical properties as a function of the process parameters are presented. Additionally, microscopic investigations of the bonding zone are discussed. One important advantage of ultrasonic metal welding is the possibility to realise a direct contact between the load bearing fibres of the reinforced composite and the metallic surface without destroying the carbon fibres. [source] Multi-Scale Analysis of IN-718 Microstructure Evolution During Linear Friction WeldingADVANCED ENGINEERING MATERIALS, Issue 6 2008C. Mary The present investigation focuses on Linear Friction Welding of a widely used Ni-based superalloy: IN-718. Blocks of commercial IN-718 alloy were linear friction welded under optimized processing conditions and the evolution of the weld joint microstructure was investigated using optical and scanning electron microscopy. In particular, visual examinations and macroscopic observations of microstructure evolution in the transverse cuts through the weld revealed a specific shape and a dual nature for the flash. [source] Cruciform fillet welded joint fatigue strength improvements by weld metal phase transformationsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2008PH. P. DARCIS ABSTRACT Arc welding typically generates residual tensile stresses in welded joints, leading to deteriorated fatigue performance of these joints. Volume expansion of the weld metal at high temperatures followed by contraction during cooling induces a local tensile residual stress state. A new type of welding wire capable of inducing a local compressive residual stress state by means of controlled martensitic transformation at relatively low temperatures has been studied, and the effects of the transformation temperature and residual stresses on fatigue strength are discussed. In this study, several LTTW (Low Transformation-Temperature Welding) wires have been developed and investigated to better characterize the effect of phase transformation on residual stress management in welded joints. Non-load-carrying cruciform fillet welded joints were prepared for measurement of residual stresses and fatigue testing. The measurement of the residual stresses of the three designed wires reveals a compressive residual stress near the weld toe. The fatigue properties of the new wires are enhanced compared to a commercially available wire. [source] Interaction equations for multiaxial fatigue assessment of welded structuresFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2004M. BÄCKSTRÖM ABSTRACT Multiaxial fatigue data from 233 welded test specimens taken from eight different studies have been evaluated based on three published interaction equations for normal and shear stress. The interaction equations were obtained from SFS 2378, Eurocode 3 and International Institute of Welding (IIW) recommendations. Fatigue classes for normal and shear stress were obtained directly from the design guidance documents. Additionally, mean fatigue strengths were determined by regression analysis of bending only and torsion only data for different specimen types. In some cases, the S,N slopes assumed by the different standards were not appropriate for the test data. Specimens that showed significantly different cracking locations or cracking mode between bending and torsion were not easily correlated by the interaction equations. Interaction equations work best in cases where both the normal stress and the shear stress tend to produce crack initiation and growth in the same location and in the same direction. The use of a damage summation of 0.5 for non-proportional loading as recommended by IIW was consistent with experimental observations for tube-to-plate specimens. Other codes used a damage sum of unity. [source] Welding and Marking of Plastics with LasersLASER TECHNIK JOURNAL, Issue 5 2010New absorbers increase possibilities for application Today laser radiation as a tool for The Authors welding, cutting and marking in manufacturing of plastic components and products has achieved a good market acceptance. It offers an alternative to conventional processes such as ultrasonic, vibration or friction welding, mechanical cutting, milling or water jet cutting, tampon printing or ink jet printing. Main advantages for laser marking are flexibility and a contact free process [1]. Laser welding of plastics offers advantages in case of cleanness of processed components, low thermal and mechanical stress to components and inner sensitive parts as well as flexibility [2]. Although laser beam welding seems to be a relatively expensive processing method, savings can be achieved by entirely consideration of production process and logistics. [source] Laser Welding of Plastics , a Neat ThingLASER TECHNIK JOURNAL, Issue 5 2010The story of a popular laser application Industry has been dealing with the joining of plastics for over half a century. The wish for an economically viable method of joining components was there already when the injection molding process was developed. With the advent of industrial laser technology, laser welding developed into a practical solution for many plastics joining problems. [source] Maskenschweißen von Thermoplasten mittels LaserstrahlungLASER TECHNIK JOURNAL, Issue 4 2008Eine Prozessidee findet den Weg in die Industrie Viele Innovationen entstehen durch Kundenanforderungen. Oft werden diese Anforderungen durch den Stand der Technik limitiert. Beim Maskenschweißen von Thermoplasten behinderte viele Jahre die optische Leistung der Diodenlaser die Entwicklung des schnellen Verschweißens von kleinen Nähten und großen Strukturen für die Mikrotechnik und Fluidik. Die jetzt erreichten Leistungsklassen haben diese Limitierung für das Maskenschweißen aufgehoben, finden verstärkt Anwendung in der Industrie und treiben weitere Innovationen wie das High Speed Welding in den Markt. [source] Fortschritte beim Rührreibschweißen von Aluminium, Magnesium und StahlMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 9 2006S. Sheikhi Dr.-Ing. Friction Stir Welding; Aluminium; Magnesium; Steel; Tailored welded blanks Abstract Das Rührreibschweißen (Friction Stir Welding (FSW)) stellt einen innovativen Schweißprozess zum Fügen von Leichtmetallen insbesondere von Aluminiumlegierungen dar. Die Herstellung von Aluminiumverbindungen mit konventionellen Schmelzschweißverfahren erfüllt nicht immer und nicht bei jeder Legierung die von der Industrie gestellten Qualitätsanforderungen. Das Rührreibschweißen stellt eine Alternative zu den Schmelzschweißverfahren dar. Die entstehenden Schweißnähte weisen gute mechanische Eigenschaften auf, das Verfahren ist robust und seine Reproduzierbarkeit sehr gut. Im Rahmen dieser Arbeit wird der Einsatz des Rührreibschweißens zum Fügen von Aluminium- und Magnesiumlegierungen erläutert. Dabei werden artgleiche und artungleiche Verbindungen und deren mechanische Eigenschaften beschrieben. Das Rührreibschweißen von Stahl mit seinen besonderen Anforderungen an das Schweißwerkzeug wird ebenfalls vorgestellt. Progresses on the friction stir welding of aluminium, magnesium and steel Friction Stir Welding (FSW) represents an innovative welding process for joining light metal, especially, aluminium and its alloys. Friction Stir Welding offers an attractive alternative to conventional fusion welding processes because of the excellent properties (particularly ductility), reproducibility, robustness, and surface finish obtained with the process. Within the scope of this work the Friction Stir Welding-Process with its possible joint configurations is explained. The focus of this work concentrates on weldability studies concerning cladded aluminium alloys, aluminium cast alloys, aluminium tailored welded blanks both from similar and dissimilar joints produced in aluminium, magnesium and steel. The mechanical properties of the welded samples will be discussed. [source] Where Does the Lithium Go?ADVANCED ENGINEERING MATERIALS, Issue 4 2010A Study of the Precipitates in the Stir Zone of a Friction Stir Weld in a Li-containing 2xxx Series Al Alloy The main strengthening precipitates of aluminum alloy 2198-T8, which are of the T1 phase, dissolve during friction stir welding, sending many Li atoms into solid solution. The stir zone precipitates are characterized using high-resolution transmission electron microscopy, energy dispersive spectroscopy, and selected area diffraction techniques to begin answering questions about the microstructural evolution and the relationship between microstructure and mechanical properties in friction stir welding of the next generation of lightweight Li-containing Al alloys. [source] Simulation of Welding and Distortion in Ship Building,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Thomas Rieger Simulation tools will continue to gain importance for both scientific investigations and industrial applications. This further applies to welding technology. The present work focuses on the simulation of distortions due to the welding of stiffeners on heavy plates in shipbuilding. An equivalent heat source (EHS) was computed by the software SimWeld to describe the energy input caused by welding. The EHS was combined with an FEM simulation of the global structure in the commercial program SYSWELD. Therefore an interface between the SimWeld platform and SYSWELD was implemented. The simulation results were compared with a welded demonstrator. The predicted displacements correlate closely with the experimental data. Using the combined approach the quality of the prediction was significantly improved against the typical method of heat source parameter identification, which is based on experimental results. The results allow for the optimization of welding sequences and for the minimization of buckling in shipbuilding. [source] Microstructure Evolution and Mechanical Properties of Linear Friction Welded Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) Titanium Alloy Joints,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Wen-Ya Li The microstructural evolution, microhardness, tensile properties and impact toughness of Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) alloy joints welded by linear friction welding (LFW) are investigated. A narrow, sound weld is formed, consisting of a superfine ,,+,, structure in the weld center. The structure gradually changes from the weld center to the parent Ti17 in the TMAZ, with the highly deformed , and , phases oriented along the deformation direction, owing to the uneven deformation and temperature distribution. The microhardness of the TMAZ is the lowest of the distinct zones and presents a valley-like shape. The tensile strengths of the joints are comparable to that of the parent Ti17 but with a much lower plasticity and impact toughness. The microstructure variation contributes to the resultant properties. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Mater. The Cover shows a hybrid joint for multi-material lightweight components realized by ultrasonic metal welding at the Institute of Materials Science and Engineering at the University of Kaiserslautern. Ultrasonic welding is one innovative technology for joining carbon fibre reinforced polymers (CFRP) with sheet metals like aluminium alloys or aluminium plated steels. The achievable mechanical properties of the ultrasonic welded joints were carried out by using statistical test methods. One example for the evaluation of the welding results is presented on the left hand side of the Cover. Additionally a scanning electron micrograph of the bonding zone of an aluminium/CFRP-joint is shown in the background. More details about the ultrasonic welding technique can be found in the article of F. Balle, G. Wagner and D. Eifler on page 35 of this issue. [source] Ultrasonic Metal Welding of Aluminium Sheets to Carbon Fibre Reinforced Thermoplastic Composites,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Frank Balle The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. The investigations described in this paper were carried out using the ultrasonic metal welding technique for joining carbon fibre reinforced thermoplastic composites (CFRP) with sheet metals like aluminium alloys or aluminium-plated steels. The achievable mechanical properties as a function of the process parameters are presented. Additionally, microscopic investigations of the bonding zone are discussed. One important advantage of ultrasonic metal welding is the possibility to realise a direct contact between the load bearing fibres of the reinforced composite and the metallic surface without destroying the carbon fibres. [source] Joining Strategies for Open Porous Metallic Foams on Iron and Nickel Base Materials,ADVANCED ENGINEERING MATERIALS, Issue 8 2007S. Longerich Within the Collaborative Research Centre (SFB) 561 "Thermally highly loaded, porous and cooled multilayer systems for combined cycle power plants" open porous Ni-based structures are developed for the requirements of an effusion cooling. A two-dimensional cooling strategy for the walls of combustion chambers, that allows the outflow of the cooling medium over the complete wall area of the combustion chamber, could be realized by an open porous metallic foam structure. The challenge is to join the porous foam structure with the solid substrate material. Capacitor discharge welding and laser beam welding/-brazing methods seems to be promising methods due to a minimum input of energy and, connected with this, a small joining zone. [source] Microstructure Evolution and Mechanical Properties of Linear Friction Welded 45 Steel JointADVANCED ENGINEERING MATERIALS, Issue 8 2007J. Ma Linear friction welding (LFW) is an emerging solid-state joining process to extend the current applications of welding. The microstructure evolution and mechanical properties of LFW 45 steel joint were investigated. The microstructures from the weld center to the parent metal were the superfine ferrite+pearlite in the weld center, the deformed fine ferrite + pearlite in the thermomechanically affected zone, the tempered sorbite, troosite and martensite in the heat affected zone. The microhardness of the joint decreased gradually from the parent metal to the weld center. The tensile properties of the joint were significantly improved in both the strength and ductility. The microstructure evolution, microhardness variation and fracture position are attributed to the various thermal histories of different positions. [source] A fatigue and creep study in austenitic stainless steel 316L used in exhaust pipes of naval gas turbinesFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004R. F. MARTINS ABSTRACT Exhaust pipes of naval gas turbines are made of thin wall tubing of stainless steel grade AISI 316L. The tubes are fabricated by butt welding of different sections with longitudinal and circumferential joints. The plate thickness is about 4.0 mm, and the working temperature varies between 600 °C and 400 °C in the critical zones of the pipe, in the lower and central areas, respectively. The loadings in the tube induce high-temperature fatigue and creep-fatigue cracks have nucleated and propagated in the tube near some welded joints. The paper presents FCGR data obtained in CT specimens of used material taken from the pipes and tested at RT, 335, 500 and 600 °C. Preliminary creep data obtained in tension, in thin-sheet specimens (about 4 mm thickness), also taken from the conduct wall and tested at 500, 550 and 600 °C are also given. These results are crucial to perform a fatigue-creep interaction life assessment of the critical parts of the structure in the near future. Finally, the paper presents results of research work to investigate carbide precipitation and formation in virgin thin-sheet specimens subjected to several types of thermal exposures. In some cases, 3,4 d was the time interval between exposures. Grain size measurements were carried out together with microstructural observations in the SEM. The influence of time, temperature and time interval between thermal exposures was assessed comparing the microstructures. [source] Strong Carbon-Nanotube,Polymer Bonding by Microwave Irradiation,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2007Y. Wang Abstract The vigorous response of multiwalled carbon nanotubes (MWNTs) to microwave irradiation, leading to the release of a large amount of heat, is used to locally melt a plastic matrix adjacent to the nanotubes within a period of seconds. This results in the intercalation of the MWNTs into the polymer matrix at room temperature without any physical damage to the polymer. The so-called "microwave welding" approach creates a new paradigm for the formation of very strong MWNT,polymer bonds without the use of any adhesive, and represents a significant step forward for the fabrication of functional nanotube composites. Here, we demonstrate the implications of the anisotropic alignment of MWNTs in polymers, patterned conductors/resistors for soft electronics, and high-strength composites, where the MWNTs are ,soldered' to flexible polymer substrates. [source] Multichannel surface electromyography in ergonomics: Potentialities and limitsHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2010Marco Gazzoni Abstract The prevention of work-related musculoskeletal disorders is one of the main goals in ergonomics. Among others, surface electromyography (sEMG) is an important tool for the evaluation of risks related to work activity. Three main issues have been approached in ergonomics via sEMG: 1) the analysis of muscle activation, 2) the analysis of exerted forces and torques, and 3) the analysis of muscle fatigue. Many studies have been carried out in static conditions. In ergonomics, however, it is more relevant to study muscle activity and fatigue during real tasks that are, in general, dynamic. From isometric to dynamic contractions, the complexity of the interpretation of sEMG signals increases considerably. Changes in sEMG signals are related to the continuous modifications in force output, muscle fiber length, and relative position of surface electrodes and sources. To increase the reliability of the information extracted from sEMG, multichannel detection systems have been applied, showing the possibility of overcoming some limits of the standard technique. Some illustrative laboratory and field studies are reported in this work to illustrate the potentialities and the open problems in the use of multichannel sEMG in ergonomics. Case 1 is a laboratory study investigating the myoelectric manifestations of fatigue in the biceps brachii (BB) during dynamic elbow flexion/extension. Case 2 is a laboratory study investigating the myoelectric manifestations of fatigue during a repetitive lifting task. Case 3 is a field study, carried out in an automotive plant, investigating muscle activation during the welding of a car door. Many factors play a leading role in the correct interpretation of information provided by sEMG. Even though multichannel sEMG provides information able to improve the estimation of force and/or fatigue during working tasks, many problems related to the signal acquisition and interpretation are still open. Further improvements are necessary to develop multichannel sEMG into an effective tool supporting other methodologies for the evaluation of work-related risks. © 2010 Wiley Periodicals, Inc. [source] Adaptive mesh technique for thermal,metallurgical numerical simulation of arc welding processesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008M. Hamide Abstract A major problem arising in finite element analysis of welding is the long computer times required for a complete three-dimensional analysis. In this study, an adaptative strategy for coupled thermometallurgical analysis of welding is proposed and applied in order to provide accurate results in a minimum computer time. The anisotropic adaptation procedure is controlled by a directional error estimator based on local interpolation error and recovery of the second derivatives of different fields involved in the finite element calculation. The methodology is applied to the simulation of a gas,tungsten-arc fusion line processed on a steel plate. The temperature field and the phase distributions during the welding process are analyzed by the FEM method showing the benefits of dynamic mesh adaptation. A significant increase in accuracy is obtained with a reduced computational effort. Copyright © 2007 John Wiley & Sons, Ltd. [source] Ultrasonic welding of advanced thermoplastic composites: An investigation on energy-directing surfacesADVANCES IN POLYMER TECHNOLOGY, Issue 2 2010Irene Fernandez Villegas Abstract Ultrasonic welding is considered as one of the most promising welding techniques for continuous fiber-reinforced thermoplastic composites. Intermolecular friction within the bulk, resulting from the application of ultrasonic waves applied on the surfaces, generates the heat required for welding to take place at the interface of the joining members via the so-called "energy directors" (EDs). Energy directors consist of resin protrusions or artificially produced asperities on the composite surfaces and play an important role both in the welding process and in the quality of the resulting welds. This paper presents the results of a study on the effects of configuration of different EDs on the ultrasonic welding of carbon fiber/polyetherimide advanced thermoplastic composites in a near-field setup. Triangular EDs were molded on the surface of consolidated composite laminates with a hot platen press. Single lap-shear-welded samples were produced to investigate the influence of the orientation of the EDs with respect to the load direction, as well as the configuration of multiple EDs. The results indicate that the configuration of multiple transverse EDs was more effective in covering the overlap area, once the resin has melted, causing only a minimum fiber disruption at the welding interface. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:112,121, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20178 [source] Mechanical strength of laser-welded cobalt,chromium alloyJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2004N. Baba Abstract The purpose of this study was to investigate the effect of the output energy of laserwelding and welding methods on the joint strength of cobalt-chromium (Co-Cr) alloy. Twotypes of cast Co-Cr plates were prepared, and transverse sections were made at the center ofthe plate. The cut surfaces were butted against one another, and the joints welded with alaser-welding machine at several levels of output energy with the use of two methods. Thefracture force required to break specimens was determined by means of tensile testing. For the0.5-mm-thick specimens, the force required to break the 0.5-mm laser-welded specimens atcurrents of 270 and 300 A was not statistically different (p > 0.05) from the results for thenonwelded control specimens. The force required to break the 1.0-mm specimens double-weldedat a current of 270 A was the highest value among the 1.0-mm laser-welded specimens. The results suggested that laser welding under the appropriate conditions improved the jointstrength of cobalt- chromium alloy. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 121,124, 2004 [source] Installing magnetic keepers using laser weldingJOURNAL OF PROSTHODONTICS, Issue 1 2002Masatoshi Ishikawa DDS Magnetic overdenture attachments can provide useful denture retention. A technique is proposed that involves installing the magnetic keeper in the overdenture abutment coping using laser welding. Compared with the conventional cast-to technique, the new technique provides a suitable contour to the abutment coping with the magnetic keeper and ensures proper mounting in the abutment coping, installing the magnetic keeper easily and effectively. [source] Welding and Marking of Plastics with LasersLASER TECHNIK JOURNAL, Issue 5 2010New absorbers increase possibilities for application Today laser radiation as a tool for The Authors welding, cutting and marking in manufacturing of plastic components and products has achieved a good market acceptance. It offers an alternative to conventional processes such as ultrasonic, vibration or friction welding, mechanical cutting, milling or water jet cutting, tampon printing or ink jet printing. Main advantages for laser marking are flexibility and a contact free process [1]. Laser welding of plastics offers advantages in case of cleanness of processed components, low thermal and mechanical stress to components and inner sensitive parts as well as flexibility [2]. Although laser beam welding seems to be a relatively expensive processing method, savings can be achieved by entirely consideration of production process and logistics. [source] Laser Welding of Plastics , a Neat ThingLASER TECHNIK JOURNAL, Issue 5 2010The story of a popular laser application Industry has been dealing with the joining of plastics for over half a century. The wish for an economically viable method of joining components was there already when the injection molding process was developed. With the advent of industrial laser technology, laser welding developed into a practical solution for many plastics joining problems. [source] Potential and limitations of laser technology in restoration of metallic objects of art and cultural heritageMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 3 2008U. Klotzbach Abstract Potential applications of laser techniques, such as precision cutting, micro welding, and ablation of stains, are presented. Concerning laser beam ablation, we explain the mechanism, and then discuss potential applications (cleaning of gilded or solid metal surfaces, cleaning of verdigris) and limits (thinning of verdigris, removing rust from verdigris). This research has been performed within the frame of a joint project sponsored by Deutsche Bundesstiftung Umwelt (DBU, German Foundation for the Environment) as well as in immediate co-operation with restorers. The presentation of these results is to propose laser technology as a promising option to be taken into account in planning and doing restoratory work. [source] The influence of artificial aging on the microstructure, mechanical properties, corrosion, and environmental cracking susceptibility of a 7075 friction-stir-weldMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 10 2007C. S. Paglia The influence of overaging to the T7451 temper on the microstructure, the mechanical properties, and the corrosion susceptibility of friction-stir-welded 7075 aluminum alloy was investigated by means of transmission electron microscope (TEM), SEM investigations, constant extension rate tests (CERT), alternate immersion tests, and potentiodynamic scans. The overaging that occurs during welding within the heat-affected zones of the friction-stir-welded 7075-O tempered plates promotes a slight formation of intragranular and grain boundary precipitates and increases the mechanical as well as the corrosion resistance properties as compared to the T7451 welded plates. The "double" overaging treatment, consisting of the T7451 temper and the thermal transient experienced by the heat-affected zones of the 7075-T7451 welded plates, increases the size of the intragranular and the grain boundary precipitates as well as the precipitate-free zones. These facts decrease the mechanical and corrosion properties of the 7075-T7451 weld. The T7451 thermal treatment applied after the welding of the 7075-O plates promotes the high presence of small precipitates and reduces the size of the precipitate-free zones. This fact increases the general corrosion resistance, but decreases the mechanical properties. Therefore, the corrosion as well as the mechanical properties are greatly correlated with minute changes in the microstructure, which can arise by short-term heat exposure as for instance during welding. It was also found that the environmental susceptibility measured by means of CERTs may be influenced by "solution-strengthening" corrosion mechanisms which increase the strain. This fact is present in weld microzones particularly susceptible to corrosion. [source] Intergranular corrosion on Nd:YAG laser-welded A653 steel for automotive applicationMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2004Y. M. Looi Abstract Laser welding techniques produce a narrower heat-affected zone than other conventional welding methods. However, laser welding is not exempt from high heat input during the welding process. This high heat input results in changes of the material properties including its corrosion behaviour; the formation of the heat affected zone increases the susceptibility of the material to intergranular attack. The residue of zinc at the weld due to condensation and splashing during the welding process may also influence adversely the corrosion behaviour of the material. The degree of susceptibility to corrosion strongly depends on the welding parameters. Electrochemical and microstructure characterisation were employed to study the influence of Nd:YAG (neodymium yttrium aluminium garnet) laser-welding on an A653 galvanized steel at different welding parameters. [source] Entwicklung hochverschleißbeständiger wolframschmelzkarbidbasierter Schichten auf Aluminiumbauteilen durch Plasma-Pulver-Auftragschweißen,MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 7 2007S. Kondapalli Dipl.-Ing. plasma transferred arc welding; wear-resistant coating; aluminium; composite coating; fused tungsten carbide Abstract Durch den Einsatz von Wolframschmelzkarbid können Funktionsflächen von Bauteilen mit stark abrasiven Beanspruchungen wirkungsvoll geschützt werden. Bereits seit vielen Jahren wird Wolframschmelzkarbid eingesetzt, um die Verschleißeigenschaften von Stahl zu verbessern. In diesem Artikel werden Ergebnisse von Untersuchungen zum Verschleißschutz von Aluminiumoberflächen mithilfe des Plasma-Pulver-Auftragschweißens von wolframschmelzkarbidbasierten Schichten vorgestellt. Die Wolframschmelzkarbid-Schichten werden mit zwei Methoden entwickelt, zum einen durch Dispergieren von Wolframschmelzkarbidpartikeln, zum anderen durch eine Kombination aus Dispergieren und Legieren von Verbundpulvern auf Wolframschmelzkarbidbasis. Die Schweißbarkeit der Pulversysteme wird für variierende Auftragschweißparameter und Karbidpartikelanteile untersucht. Im Anschluss erfolgt die Analyse der spezifischen Eigenschaften und der Verschleißbeständigkeit der entwickelten Schichten. Abschließend wird das Anwendungspotenzial am Beispiel von Führungsrollen dargestellt. Development of high wear-resistant FTC-based coatings on aluminium components using plasma transferred arc welding Nowadays, functional surfaces of components can be effectively protected from extreme wear with the help of fused tungsten carbide (FTC) coatings. The wear protection of steel components using FTC has been well known for many years. This paper presents the feasible study of improving the wear resistance of aluminium components with FTC particles using plasma powder arc welding. The FTC coatings are developed with two methods: one is the dispersion of carbide particles in aluminium and the other one is the combination of dispersing and alloying of FTC-based composite powders. In this research, coatings within a thickness range of a few millimeters are developed with varying process parameters and compositions of the filler materials. The developed coating systems are tested with regard to their specific properties and their wear resistance. Finally, their application potential is presented. [source] | |||||||||||||||||||