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Characterisation of dissimilar friction stir welded 7075 and 6101 aluminum alloys

Evolution of material properties of friction stir spot welded lap joints of AA5083-H116

  • Authors: Osinubi, Ayuba Segun
  • Date: 2020
  • Subjects: Friction stir welding , Joints (Engineering) , Welded joints , Aluminum alloys
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/479403 , uj:43359
  • Description: Abstract: There is currently high demand on the materials joining involving lap configuration of different thicknesses and sizes in most industrial sectors such as, aerospace, shipbuilding, marine, manufacturing, automobile, aeronautic, railways etc. in which friction stir spot welding actively involved. In the past, industries have been engaging the services of riveting and bolting for such lap joining and which are not effective and as such not reliable because of stress concentration at the joints. Friction stir spot welding is a novel joining technique which relies on heat generated by friction to create a sound welded joint. However, the structural integrity of the joint produced is influenced by the process parameters and materials employed. Hence, this study investigated the effect of selected parameters (rotational speed (600-1200 rpm and dwell time (5-15 s)) on the microstructure and mechanical properties of 5058-H116 Al alloy, FSSW lap joints. The understanding of the structural integrity of the produced joint drives the industrial reliance on the application of this joining process. In this study, a cylindrical tapered, H13 hot working steel tool with a probe length of 5 mm, probe diameter of 6 mm and a shoulder diameter of 18 mm was employed and the tool plunge rate was maintained at 30 mm/min in all trials. Joints produced were subjected to microstructural examination using optical microscope and scanning electron microscope. This research will focus on the characterizations of FSSW fabricated materials and carry out a study on the integrity of the produced welds... , M.Ing. (Mechanical Engineering Science)
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Surface composites and functionalisation : enhancement of aluminium alloy 7075-T651 via friction stir processing

  • Authors: Ikumapayi, Omolayo Michael
  • Date: 2020
  • Subjects: Friction stir welding , Aluminum alloys - Welding , Surfaces (Technology) , Metallic composites - Welding , Tribology
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/443819 , uj:38766
  • Description: Abstract: This research work is aimed at modifying and enhancing the properties of aluminium alloy 7075- T651 through the friction stir processing (FSP) technique, in order to improve the mechanical, electrochemical, structural, tribological as well as the metallurgical properties which include micro- and macro- structural analysis through XRD and Image processing of grain size and grain flow patterns determination, by reinforcing the parent metal. The surface modification of the parent metal has been made possible in the past via different techniques,such as laser surfacing, electronbeam welding and thermal spraying; but in recent years, the friction stir processing (FSP) technology has been adopted to cater for the complex methods of surface enhancement. FSP is well-renowned for its short route of fabrication, densification, grain refinement, homogenization of the precipitates of composite substances, nugget zone homogeneity. These have led to the efficient surface enhancement, significant and remarkable improvement in hardness, ductility, strength, increased fatigue life, as well as formability within which the bulk properties are still intact. The use of FSP in the fabrication of metal matrix composites (MMCs), especially aluminium matrix composites (AMCs) and aluminium hybrid composites (AHCs) were dealt with in this study... , Ph.D. (Mechanical Engineering)
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Friction stir processing : simulation and experimental characterizations of aluminium metal matrix composites

  • Authors: Adetunla, Adedotun Olanrewaju
  • Date: 2019
  • Subjects: Friction stir welding , Aluminum alloys - Welding
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/437050 , uj:37934
  • Description: Abstract: Aluminum (Al) and its alloys have been the prime materials of construction for many industries. The Al alloys are readily weldable and have excellent formability, good strength and excellent resistance to corrosion. While Al alloys are very strong and exhibit a high strength to weight ratio, they exhibit limited capabilities for wear and abrasion applications. The reinforcement of Aluminum and its alloys with various reinforcing powders has engineered a new type of material regarded as metal-matrix composites. The reinforcement of pure Al and its alloys with ceramic particles is expected to result in an improved mechanical property-to-weight ratio, as well as a superior resistance to wear, and to a high specific hardness. However, these composites suffer from a great loss in ductility and toughness due to the incorporation of non-deformable ceramic reinforcements as a result of inappropriate fabrication process and process parameters. The fabrication process used in this study is known as the friction stir processing technique ... , D.Phil. (Mechanical Engineering Science)
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Effect of process parameters on evolving properties of friction stir spot welds of aluminium alloy 6063

  • Authors: Mulaba-Kapinga, Delphine
  • Date: 2018
  • Subjects: Aluminum alloys - Mechanical properties , Friction stir welding
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/417176 , uj:35319
  • Description: M.Tech. (Engineering Metallurgy) , Abstract: The purpose of the research was to successfully weld AA6063 using Friction Stir Spot Welding (FSSW) and furthermore, to understand how the process parameters have an influence in the evolving metallurgical, mechanical and corrosion properties. Aluminium alloy (AA) 6063 sheets with a 2 mm thickness were used for this research study. FSSW was performed on the prepared aluminium sheets by varying the tool rotation rate at 600, 900 and 1200rpm and the dwell time at 10 and 15 seconds. The evolving microstructures, hardness properties, shear tensile behaviour, X-ray diffraction characteristics and the corrosion behaviour of the as-received material as well as the welds were studied. It was seen that the tool rotation rate played a crucial role in the testing of the mechanical properties. As the tool rotation rate increased at a constant dwell time, a smooth and debris free spot weld were seen, more HAZ formations became visible and more intermetallic phases of aluminium magnesium (AlMg) were formed although with very low peaks. Furthermore, the hardness properties increased as well up to a certain limit then decreased, and the corrosion properties to ASW (artificial Se Water) improved and the tensile shear strength improved. It would then be recommended to produce spot welds at 900rpm tool rotation rate at 10 and or 15 seconds for applications where the hardness is significant. Applications where corrosion is significant like in the marine industry, the ideal spot weld to produce would be at 600rpm for 10 seconds. A spot weld produced with an increasing tool rotation rate from 900rpm to 1200rpm at 15 seconds would also be an acceptable material in sea water. In applications where a higher tensile shear strength is required, the recommended spot weld to produce would be the one produced at 1200rpm tool rotation rate at 10 and/or 15 seconds.
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Material characterization and optimisation of friction stir welds of 6061-T6 aluminium alloy

  • Authors: Semakane, Letlhogonolo Nicholas
  • Date: 2018
  • Subjects: Friction stir welding , Welded joints - Reliability , Welded joints - Testing , Aluminum alloys
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/284076 , uj:30668
  • Description: Abstract: In this study, the effect of rotational speed and traverse speed on the micro – and macrostructure, and mechanical properties (tensile and microhardness properties) of friction stir butt-welded 6061-T6 aluminium alloy has been investigated. A number of research studies have been conducted on friction stir welding of various aluminium alloys, the rotational and traverse speeds were noticed to have a greater influence on the formation of a quality weld. In this study, welds were fabricated from different parameter combinations by varying the rotational and traverse speeds during the welding procedure. The rotational speeds employed representing the low, medium and high settings are 700, 900, and 1100 rpm respectively while the traverse speeds utilised were 60, 80, and 100 mm/min traverse speeds. To ascertain the joint integrities, the welds were characterised through hardness, microstructure, and tensile tests. The hardness test was performed along the cross-section of the welds. The changes in the microstructure and hardness were analysed and further correlated to the tensile strength of the 6061-T6 aluminium alloy. Optical microscope and Scanning Electron Microscope were used for microstructural analysis. Instron machine and Vickers hardness machine were used to perform tensile and hardness tests, respectively. The results showed that the grain size decreased from the heat affected zone (HAZ) towards the centre of the nugget zone (NZ) due to the stirring during the FSW process. The average hardness in the NZ decreased when the rotational speed varied from 700 rpm to 900 rpm, and then increased with a further increase in the rotational speed to 1100 rpm at constant traverse speeds of 60, 80 and 100 mm/min. Moreover, the ultimate tensile strength increased with an increase in traverse speed at constant rotational speeds of 700, 900, and 1100 rpm. In addition, the tensile results showed that fracture occurred in the relatively weak region which is the HAZ of the advancing side of the weld under a ductile-mode fracture. Additionally, the HAZ was found to be the soft zone in the weld due to thermal action of the FSW process and also due to the heat treatability of the aluminium alloy under investigation. It was observed that welds produced at 1100 rpm and 100 mm/min has the optimum weld quality and can be recommended for future welds in typical applications. , M.Ing. (Mechanical Engineering)
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Microstructure evolution and mechanical characterization of friction stir welded titanium alloy Ti–6Al–4V using lanthanated tungsten tool

Review on thermal, thermo-mechanical and thermal stress distribution during friction stir welding

  • Authors: Ikumapayi, Omolayo M. , Akinlabi, Esther Titilayo , Majumdar, Jyotsna D.
  • Date: 2018
  • Subjects: Friction stir welding , Thermomechanical stress , Thermal stress
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/290706 , uj:31563 , Citation: Ikumapayi, O.M, Akinlabi, E.T. & Majumdar, J.D. 2018. Review on thermal, thermo-mechanical and thermal stress distribution during friction stir welding.
  • Description: Abstract: Thermal has significant effects on the metal structure during welding process; it plays vital roles in rearranging molecular structure of the metal being welded. It is of great importance to have the knowledge of thermal, temperature, thermo-mechanical and heat distribution on the workpiece in friction stir welding as this will help in designing process and the model parameters for welding application in the following welded joints, edge butt, lap, square butt, T lap, fillet, multiple lap etc. The physics of heat generation must be explored in order to understand the workability of friction stir welding (FSW). The FSW process begun with initial friction of mechanical that took place between the tool and the welded surface resulting in the generation of heat. Since the discovery of Friction Stir Welding (FSW) in 1991, many researchers have done tremendous investigations into the process and many experimental, theoretical, numerical, empirical, computational and analytical methods have been carried out in order to analyse and optimize FSW and to understand the complex mechanism in friction stir welding at the same time to deal with effects of various parameters relating to thermal profile during the process of FSW.
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Couplant effect and evaluation of FSW AA6061-T6 butt welded joint

  • Authors: Mumvenge, Itai
  • Date: 2017
  • Subjects: Welded joints - Testing , Friction stir welding , Aluminum
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/269294 , uj:28607
  • Description: M.Ing. (Mechanical Engineering) , Abstract: Aluminium is an alloy material vastly used for manufacturing components in aviation, transport and a host of commercial use. Friction stir welding is a novelty solid state welding technique that was invented at The Welding Institute (TWI) of UK in 1991. This study presents the effects of process parameters on achieving sound welds of the friction stir butt welded joint of similar AA6061-T6 Aluminium alloys. The only parameters used and varied for this study were rotational speed and feed rate. The geometry of the tool was kept constant and the material used was tool steel, W302. Friction stir welds were evaluated both by visual inspection and non-destructive testing methods. Evaluation allowed for assessment of the weld integrity by examining for the presence of weld defects. The results indicated that the welds do not have any defects. The weld macrostructure and microstructure were examined and mechanical properties evaluated. The microhardness was also evaluated which showed that optimum speeds are required to achieve uniform hardness value across the weld traverse. The base metal showed higher hardness values when compared to the weld region. However, higher rotational speeds and higher feed rates result in increased hardness values, with the highest values recorded in the weld nugget and the least values recorded in the HAZ/TMAZ interfaces with a W-shaped hardness distribution. Couplant attenuation effect was investigated using four different types of couplants, employing Ultrasonic Testing contact pulse-echo longitudinal wave to detect weld defects. The attenuation effect was minimal when the Ultrasonic gel, oil and water were used. This was attributed to the coupling conditions such as the acoustic impedance values and the viscous properties of the couplants. Conversely, grease provided poorer frequency gain than all the couplants though it had comparable acoustic impedance values. This was attributed to its poor wetting properties and development of air pockets on contact with weld sample to be examined.
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Developing a friction-stir welding window for joining the dissimilar aluminum alloys AA6351 and AA5083

Effects of forces on the welding tool during the dissimilar joining of aluminium and copper

Microstructural evolution and mechanical characterizations of AL-TiC matrix composites produced via friction stir

  • Authors: Abegunde, Olayinka O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
  • Date: 2017
  • Subjects: Friction stir welding , Metal matrix composite , Aluminium
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/236151 , uj:24161 , Citation: Abegunde, O.O., Akinlabi, E.T. & Madyira, D.M. 2017. Microstructural evolution and mechanical characterizations of AL-TiC matrix composites produced via friction stir.
  • Description: Abstract: In this research work, ample study was conducted on the material characterization of aluminium (Al) and titanium carbide (TiC) metal matrix composites produced via friction stir welding. Different process parameters were employed for the welding process. Rotational speeds of 1600 rpm to 2000 rpm at an interval of 200 rpm and traverse speeds of 100 to 300 mm/min at an interval of 100 mm/min were employed for the welding conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS) platform. The characterizations carried out include optical microscopy and the scanning electron microscopy analyses combined with Energy Dispersive Spectroscopy (SEM/EDS) techniques to investigate the particle distribution, microstructural evolution and the chemical analysis of the welded samples. Vickers microhardness tests were used to determine the hardness distribution of the welded zone and tensile testing was conducted to quantify the strength of the welded area to the base metal in order to establish the optimal process parameters. Based on the results obtained from the characterization analysis, it was found that the process parameters played a major role in the microstructural evolution. Homogenous distribution of the TiC particles was observed at high rotational speed of 2000 rpm and low traverse speed of 100 mm/min. The highest hardness value was measured at the stir zone of the weld due to the presence of the TiC reinforcement particles. The tensile strength also increased as the rotational speed increased and 92% joint efficiency was recorded in a sample produced at 2000 rpm and 100 mm/min. The EDS analysis revealed that Al, Ti and C made up the composition formed at the stir zone. The optimum process parameter setting was found to be at 2000 rpm and 100 mm/min and can be recommended.
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Weld reliability characterisation of dissimilar friction stir welds of aluminium alloys

  • Authors: Azeez, Sarafadeen Tunde
  • Date: 2017
  • Subjects: Friction stir welding , Dissimilar welding , Welded joints - Reliability , Metals - Weldability , Aluminum
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/269883 , uj:28676
  • Description: D.Phil. (Mechanical Engineering) , Abstract: Welding is a crucial joining technique that is generally employed in the fabrication industry. The integrity of weld joints is of great importance, because of its safety and the economic implications. This research provides a glimpse into the basic concept of weld reliability, failure prediction, mechanical and microstructure characterization, with respect to friction stir welding (FSW) of similar and dissimilar Aluminium alloys. The establishment of this concept will enhance welds in service performance and their application in setting criteria for the evaluation of materials’ integrity. Friction stir welding (FSW) of a 6 mm thick AA6082-T6 Aluminium alloy was performed for the preliminary experiment. Three welding speeds of 90 mm/min, 120 mm/min and 150 mm/min at a tool-rotational speed of 950 rpm were used. A solution heat treatment carried out on the specimen revealed a drastic response by an over 120 % increment in strength. The welds at welding speed 150mm/min and the tool-rotation speed of 950rpm (i.e. sample S3) have maximum UTS values of 101MPa at as-weld and 234MPa after heat treatment (i.e. sample H3). The lowest values of strength were observed at 84MPa, at as-weld (i.e. sample S2) and 167MPa when heat-treated (i.e. 90mm/min and 950rpm, sample H1), respectively. The higher the heat input the softer the weld joints. However, the as-weld samples (S1-S6) deviate from the conventional trend unlike the heat treated samples (H1-H6). This is due to overlapping of the temperature field for friction stir bead at the end of each welds. All the samples (i.e. similar welds) fractured at the heat-affected zone (HAZ), due to the reduction in hardness, as a result of a dissolution mechanism. Aside from the point of fracture, the disparities in composition evolution and physical integrity of the weld joints are similar. Ductility is a material property that is inversly related to the strength of the materials. However, a solution heat treatment of the samples (H1-H6) has an increment of over 120% in UTS...
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Effect of plunge depth on weld integrity of friction stir welds of dissimilar aluminium and copper

Effect of rotational speed on joint inegrity of friction stir lap welded aluminium

  • Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
  • Date: 2016
  • Subjects: Friction stir welding , Aluminum , Rotational speed
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/93262 , uj:20326 , Citation: Akinlabi, E.T. & Akinlabi, S.A. 2016. Effect of rotational speed on joint inegrity of friction stir lap welded aluminium.
  • Description: Abstract: Friction stir welding is a newly developed solid state welding process, which was developed by The Welding Institute in the year 1991. The development of FSW has allowed the process to be used in different applications for different industries, which include aerospace and automobile industry. Due to the increase in the demand of high strength and low weight components in different manufacturing applications, there is a need for using pure aluminium and its alloys in lap configuration. Research studies are required to characterize and obtain optimum process parameters, which can be used to produce good quality lap welds. This paper reports lap welded 1050 Aluminium Alloy using friction stir welding process and established the effect of rotational speed on the joint integrity of the welds. The welds were produced by varying the rotational speed in the range of 1200 and 2000 rpm, and maintaining the traverse speed constant at 150 mm/min. The welds were characterized through microstructural evaluation, microhardness profiling and tensile testing in order to determine the joint integrity of the welds. The results from the macrograph of the welded joints, show a basin shaped nugget resulting from the stirring of the tool during the welding process. Fine and equiaxed grains characterized the microstructure in the stirred zone, which was a result of a dynamic recrystallization. The tensile test data revealed that as the tool rotational speed was increased, the fracture strength also increases, the highest value of the fracture strength was 195 N/mm and was found on the welds produced at 2000 rpm. High Vickers microhardness values were measured at the nugget zone with the highest value found to be 31.88 HV. It was revealed that the welds produced at the rotational speed of 2000 rpm exhibited the optimum welding parameters to join 1050 Aluminium Alloy.
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Effects of multi-pass friction stir processing on aluminium

  • Authors: Oyindamola, Kayode
  • Date: 2016
  • Subjects: Friction stir welding , Aluminum alloys
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/493265 , uj:45081
  • Description: Abstract: Friction stir processing (FSP) is a new solid-state processing technique for microstructural modification based on friction stir welding (FSW) developed by The Welding Institute (TWI) in 1991. Since its invention, the process has continually been improved, and its scope of application expanded leading to industrial applications and commercialisation in the microstructural modifications of materials to achieve desired mechanical properties. The literature review investigates studies already conducted in the field of FSP on different aluminium materials. However, no published work on the correlation of microstructural homogeneity in multi-friction processed zone with mechanical properties seem to exist despite the fact that inhomogeneity in the friction processed zone might be a reason for the degradation in mechanical properties of single-pass FSP processed materials. This dissertation focuses on the effect of multi-pass FSP on aluminium. FSP was conducted using constant rotational and transverse speeds of 1600 rpm and 40 mm/min respectively. A tool plunge depth of 5.3 mm and a 3° tilt angle was used. AA6061-T6 was the selected matrix alloy, and its microstructural homogeneity in correlation with the evolving mechanical properties after each successive FSP pass was studied in detail. Macrostructural and microstructural characterisation was carried out with an optical microscope (OM) and a scanning electron microscope (SEM), while tensile testing, and microhardness profiling was carried out to evaluate the mechanical properties of the processed materials using a tensile testing machine and a Vickers microhardness tester respectively. A study of the underlying thermodynamics occurring during the FSP process was also conducted using molecular dynamics (MD) simulation. The macrostructural and microstructural evaluations of the processed samples revealed an increase in microstructural homogeneity as the number of FSP passes increases. The correlation of this homogeneity with the resulting mechanical properties indicates that a nearly 100% homogenous friction processed zone improved the mechanical properties in the processed aluminium materials. However, the BM was found to have better mechanical v properties with an ultimate tensile strength (UTS) of 338 MPa, a yield strength of 311 MPa, and an average Vickers microhardness of 99 HV, compared to the fully homogenous processed zone with a UTS of 177 MPa, yield strength of 172 MPa, and average Vickers microhardness of 67 HV. The resulting microstructural evolution and grain sizes after each FSP pass have also been observed to be strongly dependent on the processing parameters, thermal cycle, and presence of second-phase precipitates, rather than only on microstructural homogeneity. The results obtained from the MD simulation prove that it is possible to adequately represent MD simulations of FSP on aluminium alloys. The underlying thermodynamics was explained, and consistency between experimental FSP and the simulation process was achieved. , M.Eng. (Mechanical Engineering)
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Force feedback analysis: friction stir welding of aluminium metal matrix composite

Microstructural characterization of friction stir lap welds of aluminium incorporated with titanium carbide

  • Authors: Abegunde, O. O. , Akinlabi, Esther Titilayo , Madyira, D. M.
  • Date: 2015-07-01
  • Subjects: Aluminium , Friction stir welding , Titanium carbide , Aluminum
  • Type: Article
  • Identifier: uj:5123 , ISBN 9789881404701 , http://hdl.handle.net/10210/14085
  • Description: In this research study, the characterization of the microstructure evolution of friction stir lap welds (FSLW) of Aluminium incorporated with Titanium Carbide powder to form Aluminium based composites is presented. The Titanium Carbide powder was infused at the weld interface to produce a composite. The FSLW were conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS). Different welding parameters were used for the welding process. Rotational speeds of 1600 rpm and 2000 rpm and transverse speeds of 100 mm/min, 200 mm/min and 300 mm/min were employed. The process parameters were carefully selected to represent a low, medium and high setting for the feed rates. The microstructural evolution of the samples were studied. Optical microscope and scanning electron microscopy (SEM) techniques were used to investigate the particle distribution of the welded samples. The results obtained revealed the influence of the welding parameters on the particle distribution of the welded samples. A homogenous mixture of the materials was observed at higher rotational speed of 2000 rpm.
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Characterisation of the evolving properties of friction stir spot aluminium and copper welds

  • Authors: Mubiayi, Mukuna Patrick
  • Date: 2015
  • Subjects: Friction stir welding , Dissimilar welding , Aluminum
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/213368 , uj:21144
  • Description: Abstract: Dissimilar metal joining techniques are necessary for the manufacturing of a number of structures and parts in the industries. Aluminium and copper are widely used in engineering structures, due to their unique performances, such as higher electrical conductivity, heat conductivity, corrosion resistance and mechanical properties even if they have considerable differences in their melting points. Among the aims for future years in the automotive industry is the development and implementation of new technologies, including a broad application of friction stir spot welding (FSSW) of similar and dissimilar materials. Friction stir spot welding (FSSW) is a variant of friction stir welding (FSW) for spot welding applications. Joining aluminium and copper to meet the requirements from the electrical industry have been conducted by using different joining techniques, such as ultrasonic welding, friction welding and laser welding. However, the major challenge with these techniques is the occurrence of brittle intermetallic compounds in the joint zone. FSSW has been successfully used to join aluminium and copper by a few researchers; but more research is needed to investigate the evolving properties of FSSW between copper and aluminium. The current research project joined 3 mm thick AA1060 and C11000, by using friction stir spot welding (FSSW), and by using different tool geometries namely a flat pin/flat shoulder and a conical pin/concave shoulder and different process parameters, in order to fill the gap in the literature in this field of study. Limited research results exist on friction stir spot welding between aluminium and copper. However, the successful joining of these two materials has the potential for many applications in the industry. The spot welds were produced and characterised through optical microscopy, and by scanning electron microscopy for the microstructural evolution; while the chemical and phase identification were analysed using energy dispersive spectroscopy and X-ray diffraction, respectively. Furthermore, tensile testing, microhardness profiling, residual stress analysis, electrical resistivity and statistical analysis were also conducted. This was done to investigate the relationship between the process parameters, the tool geometry and the produced welds. The real time forces acting during the welding process were monitored and analysed. It was observed that the maximum forge... , D.Phil. (Mechanical Engineering Science)
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Characterisation of tool geometries for friction stir lap welds of aluminium and copper

  • Authors: Ewuola, Oluwatoyin Olabisi
  • Date: 2015
  • Subjects: Friction stir welding , Dissimilar welding , Welded joints - Cracking , Aluminum , Copper
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://ujcontent.uj.ac.za8080/10210/370322 , http://hdl.handle.net/10210/212826 , uj:21032
  • Description: Abstract: The patenting of the Friction Stir Welding (FSW) process in 1991 opened up a process that was known within a relatively small circle of researchers to the entire research community. As a ground-breaking process in the field of joining, FSW offered a chance for the types of joining that had been fraught with lots of difficulties using the prevalent traditional means of joining. Dissimilar metal joining had been plagued with more challenges compared to similar metal joining due to issues related to differences in thermal expansion and conductivity, wettability, melting properties, microstructural properties and other material properties. Fusion welding of some dissimilar materials such as Aluminium and titanium; Aluminium and Steel had been nearly impossible; the few welds that were successful resulted in defects (like wormhole, lack of penetration, porosity, cracks) and welding imperfections. Hence, the advent of FSW, a solid state welding technique, provided a way out of the many difficulties that arise in the joining of dissimilar metals. Aluminium and copper are also two of such dissimilar metals whose material properties make them useful for a wide range of applications. However, due to the wide differences in their material properties, both metals had been difficult to join using the fusion welding technology. Recently, lots of successes have been achieved in the joining of both dissimilar metals using FSW and a lot of these are recorded in the open literature. Nonetheless, most of the successes recorded in the FSW of aluminium and copper have been in the butt weld configuration. Literatures abound on the FSW of aluminium and copper in butt configuration, while there are... , M.Phil. (Mechanical Engineering)
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