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1
Weimann, David Herbert. "A study of welding procedure generation for submerged-arc welding process." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317488.
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Dialami, Narges. "Thermo-mechanical analysis of welding processes." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/276167.
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This thesis deals with the numerical simulation of welding processes. The analysis is focused either at global level, considering the full component to be jointed, or locally, studying more in detail the heat affected zone (HAZ). Even if most of the considerations are quite general, two specific welding technologies are studied in depth: multi-pass arc welding and its extension to Shaped Metal Deposition (SMD) processes (global level analysis) and Friction Stir Welding (FSW) technology (local framework).
The analysis at global (structural component) level is performed defining the problem in the Lagrangian setting while, at local level, both Eulerian and Arbitrary Lagrangian Eulerian (ALE) frameworks are used. More specially, to model the FSW process, an apropos kinematic framework which makes use of an efficient combination of Lagrangian (pin), Eulerian (metal sheet) and ALE (stirring zone) descriptions for the different computational sub-domains is introduced for the numerical modeling. As a result, the analysis can deal with complex (non-cylindrical) pin-shapes and the extremely large deformation of the material at the HAZ without requiring any remeshing or remapping tools.
A fully coupled thermo-mechanical framework is proposed for the computational modeling of the welding processes proposed both at local and global level. A staggered algorithm based on an isothermal fractional step method is introduced.
To account for the isochoric behavior of the material when the temperature range is close to the melting point or due to the predominant deviatoric deformations induced by the visco-plastic response, a mixed finite element technology is introduced. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear/linear P1/P1 interpolations for displacement (or velocity, ALE/Eulerian formulation) and pressure fields, respectively. The same stabilization strategy is adopted to tackle the instabilities of the temperature field, inherent characteristic of convective dominated problems (thermal analysis in ALE/Eulerian kinematic framework).
At global level, the material behavior is characterized by a thermo-elasto-viscoplastic constitutive model.
The analysis at local level is characterized by a rigid thermo-visco-plastic constitutive model. Different thermally coupled (non-Newtonian) fluid-like models as Norton-Ho¿ or Sheppard-Wright, among others are tested.
The balance of energy equation is solved in its enthalpy format for a treatment of the phase-change phenomena. An accurate definition of the heat source (laser, arc, electron beam, etc), as well as the heat generation induced by the visco-plastic dissipation or the frictional contact (Coulomb and Norton model) are described.
An ad-hoc technique to account for the use of a filler material in the shape metal deposition (SMD) process is developed. The element activation methodology proposed allows for an accurate layer-by-layer deposition of the material without introducing spurious stress/strain fields.
To better understand the material flow pattern in the stirring zone, a (Lagrangian based) particle tracing is carried out while post-processing FSW results. The final numerical tool developed to study the FSW process is able to give detailed information concerning the characteristics of the weld and their relationship with the welding process parameters (e.g. advancing and rotation velocities).
The simulation tool presented in this work is validated with analytical results and calibrated with experimental data.
This thesis is a collection of research articles supplemented with some introductory chapters summarizing the state-of-the-art, the motivations and objectives of the work as well as the main contributions and some suggested lines for future work. It comprises 7 already-published (or accepted for publication) peer-review journal articles which are integral part of this work.
3
Shannon, Geoff. "Laser welding of sheet steel." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240883.
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Vairis, Achilles. "High frequency linear friction welding." Thesis, Online version, 1997. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.389136.
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Rashid, Haroon. "Butt fusion welding of polyethylene pipes." Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/6623.
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The butt fusion process is extensively used in the joining of polyethylene (PE) pipes by the water and gas industries. This welding process although deceptively simple, is rather poorly understood, with much of the initial developments being of a rather empirical nature. The Water Research centre (WRc) have funded the present research in an attempt to optimise the welding of high pressure pipeline (PE100) systems. The main aims of this research were to investigate the effect of different welding conditions on the physical and mechanical properties of the joints produced and to investigate these effects on the micro- and macro-structures of the joints produced. A series of welds were made using Eltex Tub 124 and Rigidex 002-50 pipes of 180mm diameter. The fusion pressure and heatsoak times were varied. A milling machine witha twin cutter arrangement was used to obtain the test specimens from around the circumference of the pipes. Differential scanning calorimetry was used to study the effect of sample preparation methodology on the thermo-oxidative stability. Polarised light microscopy and image analysis were used to study the macro- and micro-structural developments in the weld joint. Joint strength was evaluated via standard and non-standard tensile test methods. Milling the samples to produce the test specimens was found to decrease significantly the thermo-oxidative resistance of the polymer. Reasons for this behaviour have been proposed. In order to achieve high quality thin films from microtomy, custom-made blades were used. This programme also developed the optimum polishing method for the microtomed blades. The macro-structure of the bead: its shape and dimensions were found to be a function of temperature and pressure. Correlation was found between the bead geometry and the position around the circumference of the pipe. The macrostructures within the weld zone also showed this dependence on the position along the circumference of the pipe. An examination of the microstructures of each weld had shown the presence of five different zones. The feasibility of using microtomed thin sections in a tensile test was demonstrated. The test method provides a means to study failure initiation and propagation in the tensile test specimen. Initial deformation was found to occur in the centre of the melt-affected zone (MAZ) and the final failure occurs at the junction of the weld bead and the bulk polymer. Tests on films without the weld bead showed that maximum deformation occurred at the centre of the sample within the MAZ. The presence of the bead and the asymmetry in the test specimens caused by the welding process were found to have a significant influence on the failure mode and the failure strain. The strain rate was also found to play a significant role in both beaded and debeaded samples. The failure was initiated from the pseudo notches in the beaded samples. In the debeaded sample the failure was within the MAZ.
6
Olfert, Mark Randall. "Fundamental processes in laser drilling and welding." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0026/NQ51218.pdf.
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Mackwood, Andrew. "Numerical simulations of thermal processes and welding." Thesis, University of Essex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272572.
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Longfield, Nicholas Peter. "An investigation of ultrasonically modified laser welding." Thesis, Coventry University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364684.
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Oliveira, Santos J. F. "Controlled transfer MIG welding of stainless steel." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373993.
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Philpott, M. L. "Direct arc sensing for robot MIG welding." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376205.
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Abu, Bakar Nooh. "ESWELPD : an expert system for the generation of welding procedure of arc welding processes." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/33209.
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The research is focused on the development of an expert system to generate welding procedures for arc welding processes. The system has been developed on an IBM AT microcomputer, using an expert system shell KES (Knowledge Engineering System), a product of Software Architecture & Engineering Inc. The system is primarily intended for novice users, hence good 'help' facilities and graphical representations are provided in the system.
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Campbell, Stuart William. "Shielding gas parameter optimisation in arc welding processes." Thesis, University of Strathclyde, 2015. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25988.
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This thesis is focussed on shielding gas optimisation in gas shielded arc welding processes, and has been conducted along two themes; deriving conditions in which the shielding gas flow rate can be safely reduced, and through the highly novel process of alternating shielding gases. The correct shielding gas flow rate is essential for providing adequate protection to the weld metal during the heating, liquid and solidification stages. Hence, there is an optimum shielding gas flow rate, but this is difficult to define and is often decided on the basis of preference or experience. A multi-disciplined, systematic study has been conducted, which has shown that there is considerable scope to reduce the shielding gas flow rate. Experimental trials have shown that the shielding gas flow rate can be reduced, in a draft-free environment, to 6 l/min, with no degradation in weld quality for the worst draft conditions measured in a typical shipyard fabrication hall, at 10 l/min. This study has resulted in shielding gas flow controllers, preset at 12 l/min, being installed in a large shipyard environment, removing the welding operatives ability to increase the shielding gas flow rate. The application of alternating shielding gases offers clear manufacturing cost reduction benefits which arise from measurable increases in productivity, improved distortion control and re-work reduction, and overall improvements to the mechanical properties of the weld. Arc pressure measurements, and the subsequent derivation of forces acting on the liquid weld metal, have indicated that flow vectors for helium are opposite in direction to that produced by argon, creating a dynamic action within the weld pool. Schlieren visualisation has shown that there is a greater degree of helium entrainment in the primary jet due to a constriction of its flow in the secondary jet, influencing the arc's behaviour and inferring more of the associated benefits.
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Ho, Yeu-Chuan 1960. "DESIGN OF ARC WELDING PROCESSES: A CAUSAL PERSPECTIVE." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291663.
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The ability to make rational decisions based on the synthesis of various pieces of information and to eventually arrive at an integrated design plays a very important role in everyday engineering practice. In this paper, a conceptual framework for manufacturing design is obtained through a causal perspective. This framework is used in developing a knowledge-based system that gains insight into the process of arc welding from a few detailed analyses and experiments on simplified models and rationally arrives at an integrated design of the actual process using a hybrid axiomatic-algorithmic approach for design synthesis. The design strategy presented here may also be applied to any manufacturing process in general.
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Dunk, Kevin John. "An attribute design method for flexible welding systems." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357536.
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Ooi, Cheng Lee. "Waveform effects in bipolar TIG welding of aluminium." Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283811.
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Ghasemshahi, Mehrdad. "PIKBES : expert system for welding process quality control." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/28017.
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The present research has arisen from a continuation of the WRAPS (Welding Robotic Adaptive Programming and Simulation) project at Loughborough University, and its development as the supervisory controller of a flexible welding system. A knowledge based expert system (PIKBES) has been developed for on-line expert modification of pre-programmed welding procedures during fabrication of batches in a flexible adaptive robotic welding environment.
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Goodarzi, Massoud. "Mathematical modelling of gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27936.pdf.
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Hirst, Adrian Anthony. "Fume formation in flux cored metal inert gas welding." Thesis, University of Bradford, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306180.
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Martin, Peter James. "Experimental and rule-based approaches to arc welding procedure development." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317462.
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Gouveia, H. N. "The coupling mechanisms in the CO2 laser welding of copper." Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282175.
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Kondety, Ramaiah. "The welding of multilayer wrappers using the NG-GMAW process." Thesis, Cranfield University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284913.
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Smati, Z. "Development of a pulsed MIG system for fully automatic multipass welding." Thesis, Brunel University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355152.
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Abou-Ali, Mohamed. "An expert system for optimised process planning in fabrication and welding." Thesis, Open University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303548.
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Tan, Cheng Peng Henry. "Measurement and finite element modelling of temperatures in welding processes." Thesis, University of Strathclyde, 2005. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21621.
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Out-of-plane welding distortion has been a persistent problem in welding industries. In order to find solutions for such a problem, substantial experimental and computer modelling work on residual stresses and out-of-plane distortion analysis need to be carried out. Such computer modelling requires the temperature fields or histories during welding as pre-requisite input which can be obtained either from actual measurement or computer simulation. The object of this thesis is to develop computational techniques which can be used to compute these temperatures. Experimental work on temperature measurement has also been carried out to provide data for the purposes of validating the computer models. A data acquisition system was successfully calibrated and used to record temperature histories of the plate during the welding process. Four experiments were carried out by joining rectangular plates of size 500 min by 250 min together with "V" weld-preparation configuration at various thicknesses. Thermocouples were affixed to the top and bottom surfaces of the specimen at locations just within or very near to the heat affected zone and at locations remote from the heat affected zone to record the temperature history during welding and cooling. Related analytical theories were studied and used to validate the finite element models. The method of superposing the effects of a number of instantaneous plane heat sources to the plates has been investigated and used successfully for the evaluation of the temperature history of the plates where the heat input varies with time. Finally, a computational technique to simulate the temperature history near to and remote from the heat source was successfully developed using ANSYS 8.0 finite element software and applied to three-dimensional transient models, three-dimensional steady state models and two-dimensional transient sectional models. All the simulated results were in good agreement with experimental measurements.
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Sharpe, Michael Anthony. "On convection and stability of some welding and solidification processes." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/50624/.
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In this thesis a variety of problems are considered, the first of which is associated with the welding process. Experiments indicate that the shape of a weld pool is influenced by convection in the liquid metal. In recent years it has been shown that this convection is crucially affected by the Marangoni (or thermocapillary) force. Recently Craine and Belgrove ([30], [7]) have developed a two-dimensional, axisymmetric model which includes the Marangoni force on the free surface of a semi-infinite region of liquid steel when a point source of current and heat is incident on the free surface. An asymptotic solution to this problem is obtained in this thesis, and the surface tension gradient with respect to temperature, dj/dT, a parameter which is crucial to the magnitude of the Marangoni force, is found to affect every coefficient in the leading and first order asymptotic expansions. In various theoretical and experimental models purely poloidal flow bifurcates to a rotating flow. To investigate this possibility for our flow a linear stability analysis is performed on a numerically obtained poloidal solution for the flow and temperature distribution in a hemisphere (a model first derived in [7]). For the azimuthal stability mode m = 0 the equation governing the linear stability of the rotating motion is found to decouple from the corresponding poloidal equations. The poloidal and azimuthal stability equations both become unstable at different critical currents dependent on the sign and magnitude of d^/dT. An investigation of the eigenvectors indicates the onset of instability near to the point source. For the upper modes instability occurs only when m = 1 and in a very small region of parameter space. In the second part of this thesis a freezing sphere problem with flow is used to compare a sharp interface Stefan model and a diffuse interface phase-field model. Firstly a Stefan model that includes a disparity between the density of the solid and liquid phases is derived and solved numerically. This model is compared with a recent phase-field model with flow, derived by Anderson et al. in [2]. In this thesis the one-dimensional isotropic version of Anderson's model is obtained in spherical polar coordinates and using certain simplifications when the dimensionless thickness of the interface £5 is vanishingly small a leading order asymptotic expression reproduces the Stefan model with flow. The phase-field model is subsequently modified and solved numerically, and the results are compared with the sharp interface model. Close agreement is observed between these models when es < 0.01.
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Ogunbiyi, T. E. B. "Process monitoring and adaptive quality control for robotic gas metal arc welding." Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/4604.
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The aim of this research was to develop an adaptive quality control strategy for robotic gas metal arc welding of thin steel sheets. Statistical methods were used to monitor and control the quality of welds produced. The quality of welds cannot be directly measured during welding. It can however be estimated by correlating weld quality parameters to relevant process variables. It was found sufficient to do this using welding current and voltage transient signals only. The strategy developed was problem solving oriented with emphasis on quality assurance, defect detection and prevention. It was based on simple algorithms developed using multiple regression models, fuzzy regression models and subjective rules derived from experimental trials. The resulting algorithms were used to control weld bead geometry; prevent inadequate penetration; detect and control metal transfer; assess welding arc stability; optimise welding procedure; prevent undercut; detect joint geometry variations. Modelling was an integral part of this work, and as a feasibility study, some of the models developed for process control were remodelled using 'Backpropagation' Artificial Neural Networks. The neural network models were found to offer no significant improvement over regression models when used for estimating weld quality from welding parameters and predicting optimum welding parameter. As a result of the work a multilevel quality control strategy involving preweld parameter optimisation, on line control and post weld analysis was developed and demonstrated in a production environment. The main emphasis of the work carried out was on developing control models and means of monitoring the process on-line; the implementation of robotic control was outside the scope of this work. The control strategy proposed was however validated by using post weld analysis and simulation in software.
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Thomas, Angus W. "Parameter development for the MIG welding of high strength aerospace aluminium alloys." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/10762.
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Both dip and pulsed modes of metal transfer were investigated to establish which method produced the better bead geometry and penetration on 2024 and 2014 aluminium alloys using 2319 filler wire. The MIG electrode configuration used was electrode positive, which provides cathodic cleaning for aluminium alloys. Some initial work was also carried out using 6013 with 2319 as the consumable. A second part of the project involved the investigation of different combinations of shielding gas, and during both this and the previous task it was necessary to adjust the welding parameters to achieve acceptable welds. Initially, visual inspection and measurement of bead geometry were used for analysing the welds, but macrographs/micrographs, radiographs, hardness profiles and tensile tests were carried out to look more closely at the welds, once acceptable bead geometry and penetration was obtained. The microstructure was investigated to ascertain the extent of any porosity and chemical changes that might affect the mechanical performance of the joint by depletion of alloying elements in the HAZ. Pulse mode metal transfer improved the weld properties in comparison with the use of dip mode and was therefore used for all the work following the first section. During the work relating to shielding gas composition it was found that a 30% helium balance argon shielding gas produced the best results. It was observed during the speed trials that porosity increased with speeds in the region of 1000mm/min and also below 650mm/min. Pulse frequency and pulse time seemed to affect the arc performance and also influenced the levels of porosity. The need to thoroughly clean the joint area was also seen to be paramount in reducing porosity to a minimum. Hardness profiles indicated a dip in hardness just inside the HZ adjacent to the fusion line, with all tensile specimens failing at this point when the beads were left on. The tensile results carried out on 1.6mm 2024 at Cranfield using 30% helium in the shielding gas produced UTS strengths equivalent to 85% compared to parent metal strength, while those performed by Shorts produced UTS results up to 89%. This indicates an increase in strength over previous published results of 100%. Ibbotson cites two sets of TIG welds having UTS values of 191 and 194 MPa equivalent to 42% compared to parent metal strength while the welds produced at Cranfield using 30% helium in the shielding gas were 402 l\/IPa, equivalent to 86%. The tensile results for the 2mm 2014 aluminium alloy were even better, producing UTS results equivalent to 94% compared to the parent metal. With the 2014 alloys Ibbotson cites two sets of welds in both TIG and MIG and here UTS results were 221 and 243 MPa, equivalent to 55% compared to parent metal i ABSTRACT MIG Welding Aluminium alloys strength, while similar welds produced at Cranfield were 395MPa equivalent to 94%. The fractographs for this showed the start of a shear fracture indicating that the strength was nearing that of the parent material. Against these results even the thick section ]2.7mm 7150 welds having a UTS of 347MPa equivalent to 58% compared to parent metal strength look quite promising. The time trials relating to the natural age hardening process on 2024 welds confirmed that they achieve their maximum strength after 30 days, increasing by some 15% from half an hour after welding to 30 days. The use of thick section materials in the form of 12mm 2024 and 12.7mm 7150 became a requirement during the latter stages of the project with the investigation into the use of a number of commercially available filler wires dominating the research. Post weld heat treatment was seen to improve the strength of the welded joints when employing several different filler wires, but when incorporating a dual post weld heat treatment with 7150 using 1.6 5180 filler wire a marked improvement was observed. Arc monitoring techniques were used in the form of Arcwatch to log the arc voltage and welding current values, and a number of statistical evaluations were conducted during the project using the Arcwatch data. Geometrical data relating to weld bead dimensions was collected at numerous stages throughout the research and employed to build a joint prediction statistical model. This provides the end user with a means of process parameter selection and a visualisation of the influence of parameter variation on weld bead geometry. It has clearly been demonstrated that it is possible to produce viable welds using the MIG welding process with electrode positive, with comparatively low heat inputs when using a number of different high strength aluminium alloys and different composition filler W1I`CS. This piece of research has involved the welding of high strength aluminium alloys that have, in the past been classified as difficult to weld and with the 7xxx series, regarded unweldable. The results illustrate a major advancement in the welding of high. strength aluminium alloys, represent a considerable improvement in the strengths obtained in weldments using these alloys and has encouraged the U aerospace industry to pursue further research in this field.
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Will, Jon. "A study to determine the material to be included in a reference book for welders and fabricators." Online version, 2003. http://www.uwstout.edu/lib/thesis/2003/2003willj.pdf.
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Al-Dira'a, Ali Abood Essa. "An investigation into the friction welding of ceramics to metals and nimonic to nimonic." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357458.
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Kalligerakis, Kostas. "Stainless steel cladding of mild steel shafts using pulsed metal-inert-gas welding techniques." Thesis, University of Southampton, 1990. https://eprints.soton.ac.uk/411151/.
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Flint, Thomas. "Novel approaches for the modelling of heat flow in advanced welding processes." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/novel-approaches-for-the-modelling-of-heat-flow-in-advanced-welding-processes(fd47e4ea-95b2-447a-a9ad-79bf2c809978).html.
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The transient temperature fields induced by welding processes largely determine the size of the fusion and heat-affected zones, the microstructures, residual stresses and distortion both in the vicinity of the weld and in the final component as a whole. An accurate prediction of these fields relies heavily on the representation of the welding heat source, both in space and in time. The double-ellipsoidal heat source model proposed by Goldak and co-workers has been widely used to simulate the heat transferred from an electric arc to a component and to compute the induced transient temperature fields. This double-ellipsoidal distribution has worked well for many welding applications, but it is less appropriate when representing the heat transfer at the base of a groove whose width is narrow in relation to its depth. Similarly the conical heat source models used to represent the electron beam welding process, when applied in keyhole mode, are less appropriate when the keyhole terminates within the component, such as in the case of a partial penetration weld. In this work, the double-ellipsoidal heat source model is extended, and alternatives presented, to account for a wider set of welding scenarios, including narrow weld groove geometries and keyhole welding scenarios. A series of mathematically robust novel heat source models is presented and the models are validated against experimental data obtained during the application of various welding processes to an important grade of pressure vessel steel, namely SA508 Grade 3 class 1 steel. The calculation of the transient temperature fields during welding is extremely computationally expensive using numerical methods. Where available, and appropriate, analytical solutions are presented for these novel welding heat source models, coupled with analytical methods for accounting for time dependent heat input rates, to not only reduce computational cost but also to achieve precise predictions of the temperature fields. This, in turn, has the potential to contribute to improvements in safety assessments on critical welded infrastructure through improved predictions for the evolution of microstructure, mechanical properties and the levels of residual stress and distortion in welded joints.
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Harris, Thomas John. "Neural network characterisation of ultrasonic data and its use in the control of submerged arc welding." Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332840.
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Brooke, Stephen John. "The application of high power lasers to the welding of tee section joints in ship production." Thesis, University of Newcastle Upon Tyne, 1987. http://hdl.handle.net/10443/830.
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The use of computers by naval architects has revolutionised ship design and -construction management. The use of high power laser technology could similarly revolutionise production processes to produce a quantum leap in productivity. Facilitating low heat input materials processing, the laser is suited to various cutting, welding and heat treatment applications in shipbuilding to increase productivity through improved product accuracy. From these processes, the Author has concentrated on the application of high power lasers to the welding of tee section joints - the most common joint configuration in ship structures - by a single sided method (skid welding) to give both the lowest possible heat input and greatest flexibility. -Using a lOkW laser, single pass fully penetrating skid welds may be produced for joints in plate of up to 15mm thick, but using this size of laser, production parameter envelopes to produce visually and structurally sound joints reduce in size as plate thickness increases to greater than 10mm. It is shown that fully penetrating laser skid welds produced in steel conventionally used for surface vessel construction are of superior structural quality to fillet welds as required by classification society rules. The work has shown that achieving process consistency in an automated production based skid welding workstation operating with existing levels of joint tolerance will be dependent not only on well designed laser and beam delivery harware but also on suitable on-line adaptive control systems. It has been demonstrated that by employing laser skid welding for steelwork fabrication, an increase in productivity can be gained, principally through increased processing speed and improved product accuracy.
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Clucas, D. A. V. "A theoretical and experimental investigation into the variation of process parameters in the laser heating, melting and welding processes." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366419.
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Talbot, Edith. "Manufacturing process modelling of thermoplastic composite resistance welding." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83934.
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One-, two- and three-dimensional transient heat transfer finite element models are developed to simulate the resistance welding process of pre-consolidated unidirectional AS4 carbon fibre reinforced Poly-ether-ether-ketone (APC-2/AS4) laminates with a metal mesh heating element, in a lap-shear configuration. The finite element models are used to investigate the effect of process and material parameters on the thermal behaviour of the coupon size welds, yielding to a better understanding of the process. The 1-D model determines: (a) the importance of including the latent heat of PEEK, and (b) the through-thickness temperature gradient away from the edges, for different tooling plate materials. The 2-D model simulates the cross-section of the process, considering the convective and irradiative heat losses from the areas of the heating element exposed to air. The 3-D model includes the heat conduction along the length of the laminates, to fully depict the thermal behaviour of the welds. Finally, the models are compared with experimental data.
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Müller-Wilderink, Henrik. "Automation of Offline Programming for Assembly and Welding Processes in CATIA/DELMIA using VBA." Thesis, Linköpings universitet, Maskinkonstruktion, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176611.
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Programming industrial robots for welding or part manipulation tasks is a time-consuming and complicated process, resulting in companies not able to implement robot systems and exploit their advantages. To reduce the time needed for programming, research is looking into ways to automate this process and reduce manual labour.In this thesis a concept for automating the programming process of industrial robots was investigated using EXCEL VBA and CATIA/DELMIA. It was done for an industrial grating model of varying sizes and configurations, resulting in a time reduction of 99% compared to manual creation. For this, the model was first automatically created from scratch for the required configuration and afterwards a robot motion was created fully automatically. The concept and modelling approach is described, and the automation approach detailed. Finally, the results are analysed and discussed.
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Perez, Perez Francisco Javier. "Modelling microstructural and interfacial phenomena in welding and irradiation processes for Fe-based systems." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/11167.
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In this thesis, different modelling techniques, including physically based molecular dynamics simulations and empirical models using neural network architectures have been used to address particular problems in the understanding of microstructural development in iron-based systems. The two main areas of investigation are concerned with the prediction of composition and mechanical properties of steel welds and the effect of irradiation on the grain boundary microstructure of a-iron, both very important industrial issues. Microstructural evolution models in steel welds require weld metal composition as their starting point. Extensive analyses have been carried out concerned particularly with the prediction of weld metal chemistry, and also complex mechanical properties such as toughness, using neural network techniques and a database developed for one pass per side submerged arc welds typical of those used in the manufacture of linepipe. The neural network techniques used were based on a Bayesian framework, implemented using Markov chain Monte Carlo methods. The results showed a significant advantage in the use of neural network models for prediction of toughness compared with simpler regression analyses. In order to study the effects of irradiation on the structure of Fe-based systems, a molecular dynamics methodology was initially set up to study the equilibrium relaxed atomic configuration of symmetric tilt and twist grain boundaries in a-iron. These structures have been classified in terms of both the energy and width of the grain boundary region and the atomic arrangement has been also analysed for the tilt models in terms of structuraJ units. Radiation damage has then been studied near the relaxed structures of a symmetrical tilt and a symmetrical twist boundary in a-iron. Collision cascades have been initiated.inthe structure by imparting an initial energy of 1 keY to a single Fe atom, i.e. a primary knock-on atom (PKA). The subsequent interaction of the cascade with the grain boundary has been studied using molecular dynamics simulations. As a result of radiation, reordering is produced in the atomic structure of the boundaries, the damage being more pronounced in the twist model studied. Clusters of interstitial atoms are produced at the boundary. Changes in the properties of the interfaces after irradiation are discussed.
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Sequeira, Michael Allan. "Conceptual design of a fixture-based reconfigurable spot welding system." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2207.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.This thesis details the conceptual design of a fixture-based, reconfigurable, automated spot welding system aimed at manufacturing various sub-assemblies of circuit breakers. The welding operations are currently done using manual welding equipment, making this stage of the assembly process highly labour intensive. A range of product models and variants are assembled in quantities requiring frequent change-overs. Low-cost automation within a developing country’s manufacturing industry, more specifically within the Republic of South Africa, is the target context. The chosen design restriction, of incorporating a part fixturing design approach, distinguishes this research from F. S. D. Dymond’s work, who addressed the same problem while restricted to a fixtureless assembly approach. A conceptual layout design was developed to address part feeding, manipulation, transportation, fixturing and welding requirements, for an entire breaker model range. A simulation model for three possible layouts of the selected conceptual design provided a means to investigate each layout’s ability to tolerate and balance variation in production requirements, and to establish objective comparative performance data. This showed that the optimal configuration consists of four single loop layout systems. The thesis concludes that the final concept possesses the flexibility to produce the primary product range. Reconfiguration for production beyond this range is assisted by the modular nature of the layout. Ultimately, a reconfigurable design should focus on a properly selected base of core product ranges, providing an expandable and reusable system. The system can be supported by manual assembly stations which handle highly variant, incompatible product ranges.
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DURAND, RICHARD ZACARIAS SANZ. "EVALUATION OF THE MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF THE GIRTH WELDING OF AN API 5L X80 STEEL TUBE BY SEMI-AUTOMATIC WELDING PROCESSES WITH GAS SHIELDING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10959@1.
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PETRÓLEO BRASILEIRO S. A.CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
O presente trabalho avalia a evolução da microestrutura e as propriedades mecânicas devido à influência do aporte de calor exercido por um procedimento de soldagem que utilizou sequencialmente dois processos de soldagem sobre um tubo de aço API 5L X80, fabricado pelo processo UOE, de um aço produzido por laminação controlada sem resfriamento acelerado. A soldagem foi realizada em um tubo de 20 de diâmetro nominal e 3/4 de espessura, fixado na posição horizontal simulando condições de campo, usando o processo MAG de curtocircuito de corrente controlada com gás de proteção CO2 (100%) para o passe de raiz e o processo por Arame Tubular com proteção gasosa Ar - CO2 (80% - 20%) para os demais passes. As propriedades mecânicas foram avaliadas segundo os ensaios mecânicos exigidos na norma API 1104, além dos ensaios de microdureza Vickers e de impacto Charpy V. As mudanças microestruturais na Zona Afetada Termicamente e Material de Solda foram avaliadas por microscopia eletrônica de varredura (MEV) e microscopia óptica. A avaliação mecânica segundo a norma API 1104 foi reprovada, onde os resultados dos ensaios de tração e Nick-Break foram aceitos e o ensaio de dobramento lateral um corpo-de-prova apresentou uma trinca superior ao comprimento máximo aceitável. Os resultados da microdureza foram aceitáveis e o resultado do impacto Charpy V, segundo a norma DNV-OS-F101, para a temperatura de 0 °C foi insatisfatório na região do metal de solda dos passes de acabamento. A região da ZTA apresentou maior energia de impacto quando comparado com o material de base à temperatura de 0 °C, embora com presença do microconstituinte A-M.
The present work evaluates the changes in the microstructural and mechanical properties of an API 5L X80 steel tube due to the influence of heat input exerted during a welding procedure that used two sequential welding processes. The tubes were manufactured using the UOE process, from steel that was produced by controlled rolling without accelerated cooling. The welding was carried out on a 3/4 thick and 20 nominal diameter pipe, while it was held in a horizontal position in order to simulate field conditions, using a controlled short circuit GMAW process with CO2 (100%) gas shielding for the root pass and a flux cored arc welding process with Ar-CO2 (80% - 20%) gas shielding for the other passes. The evaluation of the mechanical properties was done by means of mechanical tests according to the API 1104 standard, in addition to the Vickers microhardness and Charpy V-notch tests. The changes in the microstructure of the Heat Affected Zone (HAZ) and the welded metal were evaluated by means of scanning electronic microscopy (SEM) and optical microscopy. The mechanical evaluation was unsatisfactory according to the API 1104 standard, while the tensile and Nick-Break test results were acceptable. The side bend test showed a crack in a specimen that exceeded the maximum acceptable value. The Vickers microhardness results were acceptable and the Charpy V-notch result, according to the DNV-OS-F101 standard, at a temperature of 0 °C, was unsatisfactory in the weld metal region of the over cap. The HAZ region showed greater energy of impact absorption compared to the base metal, at a temperature of 0 °C, even with existence of the microconstituent M-A.
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Siores, E. "Development of a real-time ultrasonic sensing system for automated and robotic welding." Thesis, Brunel University, 1988. http://bura.brunel.ac.uk/handle/2438/5550.
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The implementation of robotic technology into welding processes is made difficult by the inherent process variables of part location, fit up, orientation and repeatability. Considering these aspects, to ensure weld reproducibility consistency and quality, advanced adaptive control techniques are essential. These involve not only the development of adequate sensors for seam tracking and joint recognition but also developments of overall machines with a level of artificial intelligence sufficient for automated welding. The development of such a prototype system which utilizes a manipulator arm, ultrasonic sensors and a transistorised welding power source is outlined. This system incorporates three essential aspects. It locates and tracks the welding seam ensuring correct positioning of the welding head relatively to the joint preparation. Additionally, it monitors the joint profile of the molten weld pool and modifies the relevant heat input parameters ensuring consistent penetration, joint filling and acceptable weld bead shape. Finally, it makes use of both the above information to reconstruct three-dimensional images of the weld pool silhouettes providing in-process inspection capabilities of the welded joints. Welding process control strategies have been incorporated into the system based on quantitative relationships between input parameters and weld bead shape configuration allowing real-time decisions to be made during the process of welding, without the need for operation intervention.
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Wehle, Michael [Verfasser], and Guido [Akademischer Betreuer] Schmitz. "Basics of process physics and joint formation in resistance projection welding processes / Michael Wehle ; Betreuer: Guido Schmitz." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1216879710/34.
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Paulo, Rui Miguel Ferreira. "Modelling of friction stir welding processes and their influence on the structural behaviour of aluminium stiffened panels." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15167.
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Doutoramento em Engenharia MecânicaAluminium stiffened panels are the basic elements of many structures with requirements of high strength/weight ratio. They are used in a wide variety of applications such as airplane wings and fuselage, ships and off-shore structures. Friction Stir Welding (FSW) process has been used in the manufacturing of such structures as an alternative of other joining techniques, such as riveting or fusion welding processes, with many advantages. The understanding of the effects of FSW processes in the structural behaviour of stiffened panels is a relevant research area, useful to avoid conservative design choices often motivated by an attempt to compensate for structural analysis uncertainties. The present work focus on the numerical simulation of FSW processes, aiming to predict its effects, and also on the numerical simulation of the longitudinal compression of aluminium stiffened panels, including these effects. The numerical model for FSW was firstly developed to simulate single plates’ joining and subsequently validated using data from experiments, also performed in the scope of this work. The validated model was afterwards adapted to simulate FSW operations on stiffened panels. Sensitivity analyses performed showed an insignificant variation in the results coming from models using distinct heat input distributions related to the geometry of the toll. On the contrary, both models showed significant sensitivity to the variations of the mechanical boundary conditions that simulate the clamping system, although the single plate model was seen to be more affected by this modelling parameter. The simulations regarding the longitudinal compression of the panels included the study of the influence of each one of the welding effects (distortion, residual stresses and material softening) on the structural behaviour. The numerical modelling of these welding effects was performed adopting two different procedures: using the results from FSW numerical analyses; and using a simplified methodology based on the literature. Regarding the compression of the panels, other modelling details were also tested and compared, such as: the numerical solving methodology; the plastic behaviour definitions of the material and the welding effects on the transversal edges. All the mentioned welding effects were able to affect the panel behaviour and, namely, the collapse load. Finally, a complementary study on initial geometrical imperfection was performed using distinct deformed shapes obtained from eigenvalue analyses and applied with different magnitudes. The variation of the collapse load with the increase of the imperfection magnitude revealed to be dependent on the shape of that imperfection.
Os painéis reforçados em alumínio são os elementos básicos de muitas estruturas que requerem alto desempenho em termos da relação resistência/peso. São usados numa ampla gama de aplicações como asas e fuselagem de aviões, navios e estruturas off-shore. Os processos de soldadura por fricção tem sido usados na manufatura dessas estruturas em substituição de outras técnicas de ligação, como a rebitagem ou processos de soldadura por fusão, com inúmeras vantagens. A compreensão dos efeitos da soldadura por fricção no comportamento estrutural de painéis reforçados é uma importante área de investigação, já que permite evitar soluções conservativas na fase de projeto, frequentemente consideradas para compensar incertezas na análise estrutural. O presente trabalho centra-se na simulação numérica do processo de soldadura por fricção, de forma a prever os seus efeitos, e na simulação numérica da compressão longitudinal de painéis reforçados em alumínio incluindo esses efeitos. O modelo numérico da soldadura por fricção foi inicialmente desenvolvido para simular a ligação de duas placas e subsequentemente validado usando dados experimentais obtidos também no âmbito deste trabalho. O modelo validado foi posteriormente adaptado para simular o processo de soldadura por fricção em painéis reforçados. Estudos de sensibilidade revelaram uma variação insignificante nos resultados provenientes de simulações que usaram diferentes distribuições de calor relativas à geometria da ferramenta. Pelo contrário, ambos os modelos mostraram grande sensibilidade às variações das condições de fronteira mecânicas que reproduziam o sistema de fixação. O modelo numérico da placa mostrou ser muito mais afetado por este parâmetro de modelação. As simulações relacionadas com a compressão longitudinais dos painéis incluíram o estudo da influência de cada um dos efeitos da soldadura (distorção, tensões residuais e amaciamento do material) no comportamento estrutural. A modelação numérica destes efeitos da soldadura foi feita adotando duas diferentes metodologias: usando os resultados das análises numéricas do processo de soldadura por fricção; e usando uma modelação simplificada baseada na literatura. Ainda relativamente à compressão dos painéis, foram testados e comparados outros detalhes relativos à modelação, como: a metodologia numérica de resolução do problema; a definição do comportamento plástico do material e os efeitos da soldadura junto das extremidades transversais. Todos os efeitos da soldadura mencionados mostraram a capacidade de afetar o comportamento dos painéis, nomeadamente a sua carga de colapso. Finalmente, foi realizado um estudo complementar relativo as imperfeições geométricas iniciais atráves do uso configurações de deformação distintas, obtidas de análises de valores próprios e aplicadas com diferentes magnitudes. A variação da carga de colapso com o aumento da magnitude da imperfeição revelou-se dependente do padrão geométrico dessa imperfeição.
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Gasser, Jonathan. "AN ANALYSIS OF ENERGY RESOURCES UTILIZATION FOR TWO METAL JOINING MANUFACTURING PROCESSES." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/32.
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Sustainable manufacturing involves utilizing energy resources efficiently. Currently, the state of sustainability for a given manufacturing process is described by most in a qualitative sense as opposed to using quantitative metrics. This thesis offers a segment of analysis needed to understand the state of sustainability in the context of energy resource utilization. This was accomplished by measuring the order of magnitude difference between the energy consumption of a manufacturing process vs. the theoretical minimum amount of energy required to complete the same task (aluminum T-joint bond). This analysis was completed for a TIG welding process and a controlled atmosphere brazing (CAB) process. Also, the energy Sankey diagram was constructed for the TIG welding process. The TIG welding process and CAB process consumed an average of 136.1 ± 16.5 kJ and 6,830 ± 77 kJ respectively to bond the same sample. The TIG welding process consumed O(102 kJ) more than the theoretical minimum amount needed to complete the same bond while the CAB process consumed O(104 kJ) more than the theoretical minimum. In the context of energy consumption, there are sizable margins for improvement for both metal joining processes analyzed in this study.
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Kivineva, Esa. "The Influence of Composition and Hot Processes on Heat Affected Zone and Weld Metal Behavior and Mechnacal Properties of Ti Grade 5 and Stainless Steel." Doctoral thesis, KTH, Production Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3691.
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This thesis discusses on results of experiments carried outwith austenitic, duplex and super duplex stainless steels andTi-6Al-4V. In these it has been seen that the heat cycle duringwelding or weld simulation has a great effect on the propertiesof thematerials. The properties are related to the resultedgrain size after processing, as well as, to the chemicalcomposition of the material. The thesis discusses on the grainsize resulted after hot processing and how the properties areinfluenced by it. Also, it has been seen how large grain sizeinfluences the fracture toughness of the duplex stainlesssteel. The CTOD values become so low that an alternativeproduction method should be used instead of casting. The thesisdescribes the behavior of grain size in the hot processing ofTi-6Al-4V and impact toughness resulted by various weldingprocesses. The thesis shows correlation between grain growthbehavior of metallurgically different materials, i.e. duplexstainless steel, Ti-6Al-4V and quenced and tempered low alloysteel.
Keywords:Stainless steel, Duplex Stainless Steel,Titanium Grade 5, Ti-6Al-4V microstructure, mechanicalproperties, welding, welding simulation
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Silva, Antonio Augusto Monaco da. "An investigation on the structure, property relationships of solid state welding processes in a titanium matrix composite alloy (Ti6Al4V + 10 wt.% of TiC) /." Geesthacht : GKSS-Forschungszentrum, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015585284&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Da, Silva Antonio Augusto Monaco. "An Investigation on the Structure/Property Relationships of Solid State Welding Processes in a Titanium Matrix Composite Alloy (Ti6Al4V [plus] 10 wt.% of TiC)." Gerhard-Mercator-Universitaet Duisburg, 2006. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-01312006-125941/.
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TiC particulate reinforced Ti6Al4V metal matrix composites (Ti6Al4V 10 wt.% TiC) have high strength-to-weight ratio and good high temperature properties. Although this class of composite clearly perform better than the matrix alloy itself, the successful application of such particulate-reinforced materials depends on the availability of proven joining techniques that can produce high quality joints. Due to the high chemical reactivity of titanium that may lead to a chemical interaction with the reinforcing material a poor fusion welding performance is commonly observed in these materials making solid-state diffusion bonding and rotary friction welding potential processes to produce complex structural components. Despite recent advances in processing and manufacturing technology of Ti6Al4V 10 wt.% TiC there is still a lack of understanding in the solid state joining possibilities and its microstructural changes and mechanical properties. The main objective of this work is to investigate and analyse the feasibility of joining the particulate-reinforced composite alloy by rotary friction welding and diffusion bonding processes. It is also aimed the determination and establishment of the microstructure/properties relationships of the resultant welds as well as to investigate the bonding mechanisms and understand the weldability aspects of friction welded and diffusion bonded Ti6Al4V 10 wt.% TiC. Metallurgical characterization of both base material and welded joints was performed using Optical and Scanning Electron Microscope. Mechanical assessment was accomplished using tensile, microflat tensile and fracture toughness tests. A microstructural examination of the friction-welded joints has revealed two distinct welding zones (transformed and recrystallized zone as well as heat affected zone); while no metallurgical transformation has occurred in the diffusion bonding process. In the case of rotary friction welding best results were associated with low rotational speed and low friction pressure; while in the diffusion bonding process the best results were associated with a bonding temperature and pressure of 1000C and 5MPa together with bonding times ranging from 35 and 60 minutes.
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Scheffler, Christian [Verfasser], Reimund [Akademischer Betreuer] [Gutachter] Neugebauer, Alexander [Gutachter] Brosius, and Welf-Guntram [Gutachter] Drossel. "Electromagnetic Pulse Welding Process and Material Parameter Identification for High Speed Processes / Christian Scheffler ; Gutachter: Reimund Neugebauer, Alexander Brosius, Welf-Guntram Drossel ; Betreuer: Reimund Neugebauer." Chemnitz : Technische Universität Chemnitz, 2021. http://d-nb.info/1237047617/34.
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Cerveira, Renato Luiz Lehnert Portela. "Caracterização experimental do comportamento mecânico sob solicitação multiaxial em junções de chapas AA2024-T3 soldadas por fricção-mistura (\'FSW\')." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-17112008-161426/.
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Este trabalho tem o intuito de analisar a junção realizada pelo processo de soldagem por fricção-mistura (FSW) pelo do teste de Arcan. É apresentada inicialmente uma revisão bibliográfica dos estudos já realizados nessa área e da teoria relevante. Foram realizados ensaios para avaliar a falha da junta sob carregamento multiaxial quando comparada à falha do material base. Para a realização dos ensaios utilizouse uma máquina de tração com capacidade de 50 kN. Foi projetado e construído um dispositivo de Arcan modificado, que permite a variação do ângulo com o qual a força de tração é aplicada. Os resultados práticos demonstraram as características de resistência da junção por FSW quando sujeita à forças de tração e cisalhamento. Os resultados obtidos servem como base para comparação entre junções feitas por FSW e por métodos convencionais como a utilização de rebites (prática muito comum na indústria aeronáutica).The aim of this work is to analyze the junction made by Friction Stir Welding (FSW) using the Arcan test. Initially is presented a review of the studies carried out in this area and the relevant theory for the project. Tests were executed in order to evaluate the failure of the welding under multiaxial loading when compared to the failure of the base material. In order to execute the Arcan Tests, a tensile test machine with nominal capacity of 50 kN was used. A modified Arcan device, that allows an angle variation of the force applied, was developed and fabricated. The practical results demonstrate the FSW joint resistance characteristics when subjected to normal and shear forces. The results obtained serve as basis to compare the junctions made using FSW and conventional joint methods like rivets (very common practice in the aeronautical industry).
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Gomide, Danilo Antônio. "Análise microestrutural de revestimentos aplicados para o reparo de turbinas hidráulicas erodidas por cavitação." Ilha Solteira, 2018. http://hdl.handle.net/11449/157119.
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Orientador: Juno GallegoResumo: A cavitação ocorre inerente ao processo de produção de energia elétrica nas Usinas Hidrelétricas, ocasionando perda progressiva de massa, afetando o desempenho e potência obtidos das turbinas hidráulicas, sendo necessário o seu reparo. Visando minimizar desgaste utiliza-se uma técnica de engenharia de superfície que é aplicar uma camada de material resistente a cavitação. Dentre esses materiais destacam-se os aços inoxidáveis com cobalto, por causa de sua dureza, baixa energia de falha de empilhamento e capacidade de endurecimento por deformação. As deposições desses materiais são realizadas por processos de soldagem, como a soldagem a arco elétrico com atmosfera gasosa ou por soldagem com arame tubular, devido ao baixo custo, elevada taxa de deposição, qualidade de acabamento superficial e baixa taxa de diluição. Diante deste contexto, esse trabalho foi realizado para analisar a camada de aço inoxidável austenítico com cobalto e verificar a influência da camada de amanteigamento. Sendo assim, foram produzidas duas séries de amostra, cada uma composta por três corpos de provas, sendo diferenciadas pela energia de soldagem utilizadas no processo, obtidas pela variação da corrente de soldagem, 98 A, 143 A e 198 A. Na primeira série foi simulado uma condição de reparo das turbinas hidráulicas, utilizando como metal base o aço ASTM A36, sendo depositado sobre ele o arame AWS E70-S6, como camada de preenchimento, posteriormente foi aplicado o arame AWS E309-T1, camada de amanteiga... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Cavitation occurs inherently to the process of production of electric power in the Hydroelectric Power Plants, causing progressive loss of mass, affecting the performance and power obtained from the hydraulic turbines, being necessary its repair. In order to minimize wear, a surface engineering technique is used to apply a layer of cavitation resistant material. Among these materials stand out the cobalt stainless steels, because of their hardness, low stacking failure energy and strain hardenability. The depositions of these materials are carried out by welding processes, such as Gas Metal Arc Welding or by Flux Cored Arc Welding, due to the low cost, high deposition rate, surface finish quality and low dilution rate. Considering this context, this work was carried out to analyze the austenitic stainless steel layer with cobalt and to verify the influence of the buttery layer. Therefore, two series of samples, each composed of three test bodies, were differentiated by the welding energy used in the process, obtained by the variation of the welding current, 98 A, 143 A and 198 A. In the first group, a hydraulic turbine repair condition was simulated using ASTM A36 steel as the base metal. The AWS E70-S6 wire was deposited on it as a fill layer, after which the AWS E309-T1 wire was applied. and finally the austenitic stainless steel with cobalt was deposited as a coating. In the second group of samples were produced without the buttery layer. The microstructure was analyzed by... (Complete abstract click electronic access below)
Mestre
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Tomás, Bruno Manuel Coelho. "Magnetic pulse welding." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/4890.
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