Fracture location characterizations of dissimilar friction stir welds.
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2011
- Subjects: Fracture location , Friction stir welding , Intermetallics , Metallography
- Type: Article
- Identifier: uj:5322 , http://hdl.handle.net/10210/8230
- Description: This paper reports the tensile fracture location characterizations of dissimilar friction stir welds between 5754 aluminium alloy and C11000 copper. The welds were produced using three shoulder diameter tools; namely, 15, 18 and 25 mm by varying the process parameters. The rotational speeds considered were 600, 950 and 1200 rpm while the feed rates employed were 50, 150 and 300 mm/min to represent the low, medium and high settings respectively. The tensile fracture locations were evaluated using the optical microscope to identify the fracture locations and were characterized. It was observed that 70% of the tensile samples failed in the Thermo Mechanically Affected Zone (TMAZ) of copper at the weld joints. Further evaluation of the fracture surfaces of the pulled tensile samples revealed that welds with low Ultimate Tensile Strength either have defects or intermetallics present at their joint interfaces.
- Full Text:
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2011
- Subjects: Fracture location , Friction stir welding , Intermetallics , Metallography
- Type: Article
- Identifier: uj:5322 , http://hdl.handle.net/10210/8230
- Description: This paper reports the tensile fracture location characterizations of dissimilar friction stir welds between 5754 aluminium alloy and C11000 copper. The welds were produced using three shoulder diameter tools; namely, 15, 18 and 25 mm by varying the process parameters. The rotational speeds considered were 600, 950 and 1200 rpm while the feed rates employed were 50, 150 and 300 mm/min to represent the low, medium and high settings respectively. The tensile fracture locations were evaluated using the optical microscope to identify the fracture locations and were characterized. It was observed that 70% of the tensile samples failed in the Thermo Mechanically Affected Zone (TMAZ) of copper at the weld joints. Further evaluation of the fracture surfaces of the pulled tensile samples revealed that welds with low Ultimate Tensile Strength either have defects or intermetallics present at their joint interfaces.
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Friction stir welding of dissimilar materials – statistical analysis of the weld data
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding
- Type: Article
- Identifier: uj:5336 , ISSN 2078-0966 , http://hdl.handle.net/10210/8879
- Description: This paper reports the results of statistical analysis conducted on the weld data obtained from friction stir welding of aluminium and copper. The welds were produced by varying the process parameters; the rotational speed was varied between 600 to 1200 rpm and the welding speed varied between 50 and 300 mm/min. The Statistica (version 9.0) statistical analysis software package was used to generate the scatter and surface plots relative to the experimental results obtained from the tensile testing and the FSW data. Regression analysis was also done on the weld data. It was found that the downward vertical force has a significant effect on the Ultimate Tensile Strength of the weld and a strong relationship exist between the heat input into the welds and the measured electrical resistivities of the welds.
- Full Text:
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding
- Type: Article
- Identifier: uj:5336 , ISSN 2078-0966 , http://hdl.handle.net/10210/8879
- Description: This paper reports the results of statistical analysis conducted on the weld data obtained from friction stir welding of aluminium and copper. The welds were produced by varying the process parameters; the rotational speed was varied between 600 to 1200 rpm and the welding speed varied between 50 and 300 mm/min. The Statistica (version 9.0) statistical analysis software package was used to generate the scatter and surface plots relative to the experimental results obtained from the tensile testing and the FSW data. Regression analysis was also done on the weld data. It was found that the downward vertical force has a significant effect on the Ultimate Tensile Strength of the weld and a strong relationship exist between the heat input into the welds and the measured electrical resistivities of the welds.
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Friction stir welding process : a green technology
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Green technology
- Type: Article
- Identifier: uj:5335 , ISSN 2010-3778 , http://hdl.handle.net/10210/8878
- Description: Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materials are also presented.
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- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Green technology
- Type: Article
- Identifier: uj:5335 , ISSN 2010-3778 , http://hdl.handle.net/10210/8878
- Description: Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materials are also presented.
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Microstructural characterizations of dissimilar friction stir welds
- Akinlabi, Esther Titilayo, Reddy, Randall D., Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Reddy, Randall D. , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Scanning Electron Microscopy , Aluminum alloys , Copper
- Type: Article
- Identifier: uj:5332 , ISSN 2070-3740 , http://hdl.handle.net/10210/8871
- Description: This paper reports the microstructural characteristics of dissimilar friction stir welds between 5754 aluminium alloy and C11000 copper. Dissimilar Friction Stir Welds of 5754 aluminium and C11000 copper were produced by varying the rotational speeds between 600 and 1200 rpm and the feed rate between 50 and 300 mm/min. The welds were characterized through Scanning Electron Microscopy (SEM). The SEM analysis revealed the levels of metallurgical bonding achieved at the joint interfaces of the welds produced and it can be established that better metallurgical bonding and good mixing of both materials joined were achieved in welds produced at lower feed rates of 50 mm/min and 150 mm/min while defect population was found to be common in the welds produced at high feed rate of 300 mm/min.
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- Authors: Akinlabi, Esther Titilayo , Reddy, Randall D. , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Scanning Electron Microscopy , Aluminum alloys , Copper
- Type: Article
- Identifier: uj:5332 , ISSN 2070-3740 , http://hdl.handle.net/10210/8871
- Description: This paper reports the microstructural characteristics of dissimilar friction stir welds between 5754 aluminium alloy and C11000 copper. Dissimilar Friction Stir Welds of 5754 aluminium and C11000 copper were produced by varying the rotational speeds between 600 and 1200 rpm and the feed rate between 50 and 300 mm/min. The welds were characterized through Scanning Electron Microscopy (SEM). The SEM analysis revealed the levels of metallurgical bonding achieved at the joint interfaces of the welds produced and it can be established that better metallurgical bonding and good mixing of both materials joined were achieved in welds produced at lower feed rates of 50 mm/min and 150 mm/min while defect population was found to be common in the welds produced at high feed rate of 300 mm/min.
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Non-destructive testing of dissimilar friction stir welds
- Akinlabi, Esther Titilayo, Levy, Adrian C. S., Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Levy, Adrian C. S. , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Non-destructive testing , Aluminum alloys , Copper
- Type: Article
- Identifier: uj:5333 , ISSN 2078-0966 , http://hdl.handle.net/10210/8876
- Description: friction stir welds between 5754 aluminium alloy and C11000 copper. The Friction stir welds of 5754 aluminium alloy and C11000 copper were produced at different tool rotational speeds and feed rates. The tool rotational speed was varied between 600 and 1200 rpm while the feed rate was varied between 50 and 300 mm/min. The visual inspection and the x-ray radiographic testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the welds. No visual defects were observed on all the welds considered but the x-ray radiography technique revealed the presence of wormhole defects and discontinuities in some of the welds. It was found that the welds produced at 950 rpm with varied feed rates were the best quality welds produced and this was substantiated with the microstructural evaluation of the joint interface. It was found that these welds have good mixing and metallurgical bonding at the interfaces.
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- Authors: Akinlabi, Esther Titilayo , Levy, Adrian C. S. , Akinlabi, Stephen A.
- Date: 2012
- Subjects: Friction stir welding , Non-destructive testing , Aluminum alloys , Copper
- Type: Article
- Identifier: uj:5333 , ISSN 2078-0966 , http://hdl.handle.net/10210/8876
- Description: friction stir welds between 5754 aluminium alloy and C11000 copper. The Friction stir welds of 5754 aluminium alloy and C11000 copper were produced at different tool rotational speeds and feed rates. The tool rotational speed was varied between 600 and 1200 rpm while the feed rate was varied between 50 and 300 mm/min. The visual inspection and the x-ray radiographic testing techniques were employed to conduct the tests; these tests were conducted on the welds to ascertain the joint integrity before characterization to have an idea of the quality of the welds. No visual defects were observed on all the welds considered but the x-ray radiography technique revealed the presence of wormhole defects and discontinuities in some of the welds. It was found that the welds produced at 950 rpm with varied feed rates were the best quality welds produced and this was substantiated with the microstructural evaluation of the joint interface. It was found that these welds have good mixing and metallurgical bonding at the interfaces.
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Designs of temperature measuring device for a re-configured milling machine
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2013
- Subjects: Friction stir welding , Milling machines
- Type: Article
- Identifier: uj:4876 , http://hdl.handle.net/10210/12552
- Description: The design of temperature measuring approach for a re-configured milling machine to produce friction stir welds is reported in this paper. The product design specifications for the redesigning of a milling machine were first outlined and the ranking criteria were determined. Three different concepts were generated for the temperature measurement on the reconfigured system and the preferred or the best concept was selected based on the set design ranking criteria. Further simulation and performance analysis was then conducted on the concept. The Infrared Thermography (IRT) concept was selected for the temperature measurement among other concepts generated because it is an ideal and most effective system of measurement in this regard.
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- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2013
- Subjects: Friction stir welding , Milling machines
- Type: Article
- Identifier: uj:4876 , http://hdl.handle.net/10210/12552
- Description: The design of temperature measuring approach for a re-configured milling machine to produce friction stir welds is reported in this paper. The product design specifications for the redesigning of a milling machine were first outlined and the ranking criteria were determined. Three different concepts were generated for the temperature measurement on the reconfigured system and the preferred or the best concept was selected based on the set design ranking criteria. Further simulation and performance analysis was then conducted on the concept. The Infrared Thermography (IRT) concept was selected for the temperature measurement among other concepts generated because it is an ideal and most effective system of measurement in this regard.
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Effects of processing parameters on the corrosion properties of dissimilar friction stir welds of aluminium and copper
- Akinlabi, Esther Titilayo, Anthony, Andrews, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Anthony, Andrews , Akinlabi, Stephen A.
- Date: 2013
- Subjects: Aluminium alloy , Copper , Corrosion , Friction stir welding
- Type: Article
- Identifier: uj:5019 , http://hdl.handle.net/10210/13159
- Description: The influence of friction stir welding processing parameters on dissimilar joints conducted between aluminium alloy (AA5754) and commercially pure copper (C11000) was studied. The welds were produced by varying the rotational speed from 600 to 1200 r/min and the feed rate from 50 to 300 mm/min. The resulting microstructure and the corrosion properties of the welds produced were studied. It was found that the joint interfacial regions of the welds were characterized by interlayers of aluminium and copper. The corrosion tests revealed that the corrosion resistance of the welds was improved as the rotational speed was increased. The corrosion rates of the welds compared to the base metals were improved compared with Cu and decreased slightly compared with the aluminium alloy. The lowest corrosion rate was obtained at welds produced at rotational speed of 950 r/min and feed rate of 300 mm/min which corresponds to a weld produced at a low heat input.
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- Authors: Akinlabi, Esther Titilayo , Anthony, Andrews , Akinlabi, Stephen A.
- Date: 2013
- Subjects: Aluminium alloy , Copper , Corrosion , Friction stir welding
- Type: Article
- Identifier: uj:5019 , http://hdl.handle.net/10210/13159
- Description: The influence of friction stir welding processing parameters on dissimilar joints conducted between aluminium alloy (AA5754) and commercially pure copper (C11000) was studied. The welds were produced by varying the rotational speed from 600 to 1200 r/min and the feed rate from 50 to 300 mm/min. The resulting microstructure and the corrosion properties of the welds produced were studied. It was found that the joint interfacial regions of the welds were characterized by interlayers of aluminium and copper. The corrosion tests revealed that the corrosion resistance of the welds was improved as the rotational speed was increased. The corrosion rates of the welds compared to the base metals were improved compared with Cu and decreased slightly compared with the aluminium alloy. The lowest corrosion rate was obtained at welds produced at rotational speed of 950 r/min and feed rate of 300 mm/min which corresponds to a weld produced at a low heat input.
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Friction stir welding of dissimilar materials between aluminium alloys and copper - an overview
- Authors: Mubiayi., Mukuna P.
- Date: 2013
- Subjects: Aluminium , Copper , Friction stir welding
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/390844 , uj:4847 , ISBN 978-988-19252-9-9 , http://hdl.handle.net/10210/12514
- Description: Friction Stir Welding (FSW) is a solid state welding process used for welding similar and dissimilar materials. The process is widely used because it produces sound welds and does not have common problems such as solidification and liquefaction cracking associated with the fusion welding techniques. The FSW of Aluminium and its alloys has been commercialised; and recent interest is focused on joining dissimilar materials. However, in order to commercialise the process, research studies are required to characterise and establish process windows. In particular, FSW has inspired researchers to attempt joining dissimilar materials such as aluminium to copper which differ in properties and sound welds with none or limited intermetallic compounds has been produced. In this paper, we review the current research state of FSW between aluminium and copper with a focus on the resulting weld microstructure, mechanical testing and the tools employed to produce the welds and also an insight into future research in this field of study.
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- Authors: Mubiayi., Mukuna P.
- Date: 2013
- Subjects: Aluminium , Copper , Friction stir welding
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/390844 , uj:4847 , ISBN 978-988-19252-9-9 , http://hdl.handle.net/10210/12514
- Description: Friction Stir Welding (FSW) is a solid state welding process used for welding similar and dissimilar materials. The process is widely used because it produces sound welds and does not have common problems such as solidification and liquefaction cracking associated with the fusion welding techniques. The FSW of Aluminium and its alloys has been commercialised; and recent interest is focused on joining dissimilar materials. However, in order to commercialise the process, research studies are required to characterise and establish process windows. In particular, FSW has inspired researchers to attempt joining dissimilar materials such as aluminium to copper which differ in properties and sound welds with none or limited intermetallic compounds has been produced. In this paper, we review the current research state of FSW between aluminium and copper with a focus on the resulting weld microstructure, mechanical testing and the tools employed to produce the welds and also an insight into future research in this field of study.
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Friction stir spot welding of dissimilar materials-an overview
- Mubiayi, Mukuna P, Akinlabi, Esther Titilayo
- Authors: Mubiayi, Mukuna P , Akinlabi, Esther Titilayo
- Date: 2014
- Subjects: Friction stir welding , Aluminum alloys , Pressure welding , Friction stir spot welding - Congresses , Friction welding - Congresses
- Type: Article
- Identifier: uj:5096 , ISBN 9789881925374 , ISSN 20780966 , ISSN 20780958 , http://hdl.handle.net/10210/13710
- Description: Friction Stir Welding (FSW) process was invented and experimentally proven by The Welding Institute (TWI) in 1991 for joining Aluminium alloys. Friction Stir Spot Welding (FSSW) is a variant of the FSW which is found to be environmental friendly and an efficient process. FSSW technique has been gaining ground when compared to resistance spot welding (RSW) and could be used in various industries including, automobiles, ship building, aerospace, electrical and construction. FSSW has been successfully used to join several materials used in the above mentioned industries. In this review, FSSW studies are briefly summarised in terms of the evolving microstructure and mechanical properties between aluminium alloys and other materials such as copper, steel and magnesium.
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- Authors: Mubiayi, Mukuna P , Akinlabi, Esther Titilayo
- Date: 2014
- Subjects: Friction stir welding , Aluminum alloys , Pressure welding , Friction stir spot welding - Congresses , Friction welding - Congresses
- Type: Article
- Identifier: uj:5096 , ISBN 9789881925374 , ISSN 20780966 , ISSN 20780958 , http://hdl.handle.net/10210/13710
- Description: Friction Stir Welding (FSW) process was invented and experimentally proven by The Welding Institute (TWI) in 1991 for joining Aluminium alloys. Friction Stir Spot Welding (FSSW) is a variant of the FSW which is found to be environmental friendly and an efficient process. FSSW technique has been gaining ground when compared to resistance spot welding (RSW) and could be used in various industries including, automobiles, ship building, aerospace, electrical and construction. FSSW has been successfully used to join several materials used in the above mentioned industries. In this review, FSSW studies are briefly summarised in terms of the evolving microstructure and mechanical properties between aluminium alloys and other materials such as copper, steel and magnesium.
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Friction stir welding of aluminium and copper : fracture surface characterizations
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2014
- Subjects: Aluminium , Copper , Fracture surfaces , Friction stir welding
- Type: Article
- Identifier: uj:4745 , ISSN 2078-0966 , http://hdl.handle.net/10210/11731
- Description: Butt welds of aluminium alloy and copper alloy were produced by Friction Stir Welding by varying the feed rate and keeping all other parameters constant. The final weld matrix was composed of welds produced by a constant rotational speed of 600 rpm and the feed rate varied between 50 and 300mm/min. The microstructure and fracture surfaces of the joint interfaces were investigated. The results revealed that the joint interface was characterised with mixed layers of both materials joined. The strongest weld was produced at the highest feed rate employed at 300 mm/min. The fracture surfaces were characterised with thin layers of intermetallic compounds and can be considered fit for practical applications.
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- Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
- Date: 2014
- Subjects: Aluminium , Copper , Fracture surfaces , Friction stir welding
- Type: Article
- Identifier: uj:4745 , ISSN 2078-0966 , http://hdl.handle.net/10210/11731
- Description: Butt welds of aluminium alloy and copper alloy were produced by Friction Stir Welding by varying the feed rate and keeping all other parameters constant. The final weld matrix was composed of welds produced by a constant rotational speed of 600 rpm and the feed rate varied between 50 and 300mm/min. The microstructure and fracture surfaces of the joint interfaces were investigated. The results revealed that the joint interface was characterised with mixed layers of both materials joined. The strongest weld was produced at the highest feed rate employed at 300 mm/min. The fracture surfaces were characterised with thin layers of intermetallic compounds and can be considered fit for practical applications.
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Processing parameters influence on wear resistance behaviour of friction stir processed Al-TiC composites
- Akinlabi, Esther Titilayo, Mahamood, R. M., Akinlabi, S. A., Ogunmuyiwa, E.
- Authors: Akinlabi, Esther Titilayo , Mahamood, R. M. , Akinlabi, S. A. , Ogunmuyiwa, E.
- Date: 2014
- Subjects: Friction stir welding , Friction stir processing , Materials - Mechanical properties
- Type: Article
- Identifier: uj:4995 , http://hdl.handle.net/10210/13130
- Description: Friction stir processing (FSP) being a novel process is employed for the improvement of the mechanical properties of a material and the production of surface layer composites. The vital role of the integrity of surface characteristics in the mechanical properties of materials has made the research studies into surface modification important in order to improve the performance in practical applications. This study investigates the effect of processing parameters on the wear resistance behavior of friction stir processed Al-TiC composites. This was achieved through microstructural characterization by using both the optical and scanning electron microscope (SEM), microhardness profiling, and tribological characterization by means of the wear. The microhardness profiling of the processed samples revealed an increased hardness value, which was a function of the TiC particles incorporated when compared to the parent material. The wear resistance property was also found to increase as a result of the TiC powder addition. The right combination of processing parameters was found to improve the wear resistance property of the composites produced.
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- Authors: Akinlabi, Esther Titilayo , Mahamood, R. M. , Akinlabi, S. A. , Ogunmuyiwa, E.
- Date: 2014
- Subjects: Friction stir welding , Friction stir processing , Materials - Mechanical properties
- Type: Article
- Identifier: uj:4995 , http://hdl.handle.net/10210/13130
- Description: Friction stir processing (FSP) being a novel process is employed for the improvement of the mechanical properties of a material and the production of surface layer composites. The vital role of the integrity of surface characteristics in the mechanical properties of materials has made the research studies into surface modification important in order to improve the performance in practical applications. This study investigates the effect of processing parameters on the wear resistance behavior of friction stir processed Al-TiC composites. This was achieved through microstructural characterization by using both the optical and scanning electron microscope (SEM), microhardness profiling, and tribological characterization by means of the wear. The microhardness profiling of the processed samples revealed an increased hardness value, which was a function of the TiC particles incorporated when compared to the parent material. The wear resistance property was also found to increase as a result of the TiC powder addition. The right combination of processing parameters was found to improve the wear resistance property of the composites produced.
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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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- 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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- 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)
- Full Text:
Characterization of aluminium and titanium carbide metal matrix composites produced via friction stir welding
- Abegunde, Olayinka Oluwatosin
- Authors: Abegunde, Olayinka Oluwatosin
- Date: 2015
- Subjects: Friction stir welding , Titanium alloys
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212716 , uj:21011
- Description: Abstract: The Friction Stir Welding (FSW) process was invented and developed at The Welding Institute of United Kingdom in the year 1991 for solid state joining of aluminum and its alloys. Subsequently, this welding process has been used for joining other materials like magnesium, titanium and copper alloys, stainless steels and thermoplastics. 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 transverse speeds of 100 to 300 mm/min at an interval of 100 mm/min were employed for the welding on an Intelligent Stir Welding for Industry and Research (I-STIR) Process development System (PDS) platform. The process parameters were carefully selected to represent low, medium and high for the rotation and the translation of the tool. 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 was 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 transverse 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 found 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. , M.Ing. (Mechanical Engineering Science)
- Full Text:
- Authors: Abegunde, Olayinka Oluwatosin
- Date: 2015
- Subjects: Friction stir welding , Titanium alloys
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212716 , uj:21011
- Description: Abstract: The Friction Stir Welding (FSW) process was invented and developed at The Welding Institute of United Kingdom in the year 1991 for solid state joining of aluminum and its alloys. Subsequently, this welding process has been used for joining other materials like magnesium, titanium and copper alloys, stainless steels and thermoplastics. 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 transverse speeds of 100 to 300 mm/min at an interval of 100 mm/min were employed for the welding on an Intelligent Stir Welding for Industry and Research (I-STIR) Process development System (PDS) platform. The process parameters were carefully selected to represent low, medium and high for the rotation and the translation of the tool. 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 was 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 transverse 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 found 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. , M.Ing. (Mechanical Engineering Science)
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Effect of tool geometries on butt dissimilar friction stir welds of 5754 aluminium
- Authors: Reddy, Randall Dwain
- Date: 2015
- Subjects: Friction stir welding , Dissimilar welding , Aluminum
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213567 , uj:21169
- Description: Abstract: Friction Stir Welding (FSW) is regarded as the most significant development in joining over the past two decades. In FSW, process parameters and tool geometry play a fundamental role in obtaining desirable mechanical properties and microstructures in the welded zone. The tool geometry plays an important role in producing sound friction stir welds. Tool designs are however, generally propriety to individual researchers and only limited information is available in open literature. There are however, continuous efforts to understand the material flow and the influence that the FSW tool design has on the friction stir welded material. Within industries that use various welding techniques it well known that FSW is particularly suited for the welding of aluminium; there is great potential for FSW of copper. Given the limited supply, high cost, copper theft and commercial demand associated with copper, engineers and scientists will either attempt to reduce the quantity of copper consumed by industries or alternatively replace copper with a substitute metal that exhibits similar attributable properties. On account of the limited supply and consequently the high cost associated with copper and copper alloys; the need to join aluminium and copper and its’ alloys is anticipated to increase in the near future. FSW of dissimilar alloys/metals has attracted extensive research interest due to potential engineering prominence and inherent problems associated with conventional welding methods. This research identifies the choice of suitable tool designs and process parameters to produce sound dissimilar friction stir welds of 5754 aluminium and C11000 copper. This research focuses primarily on determining the effect of FSW process parameters on the forces experienced by the FSW tool and the relationship that this has on the electrical conductivity properties of the friction stir dissimilar weld. The experimental work was performed by completing dissimilar friction stir welds on 3 mm thick butt welds of the two materials by means of an I-stir FSW platform. During the experimental work, the rotational speed was varied between 600 and 1200 rpm in intervals on 300 related to low, medium and high rotational speeds respectively and four different FSW tool geometries were tested. The first tool was a new design with a unique shoulder topography and a cylindrical pin named the “Reddy tool”. The second tool was a tool consisted of a concave shoulder and conical pin. Tests were performed using the second tool at a 0 degree tilt and at a 2 degree tilt relative to the work-piece. The third tool consisted of a concave shoulder and cylindrical pin. The forth tool design consisted of a flat shoulder and a cylindrical pin. This research forms part of the initial experimental work to determine the forces and electrical resistance of dissimilar friction stir welds of aluminium and copper by employing different tool shoulder designs. The welds were characterised through visual inspection, weld defect and material flow analysis, microstructural evaluation, electrical resistance measurements and tool forces and tool torque analysis. Microstructural evaluation results revealed complex flow patterns of copper and aluminium material. Lamellae structures composed of copper particles with a streamline shape and continuous aluminium strips were present. Some evidence of dynamic recrystallization was observed in the nugget of the defect free welds. Based on material flow evaluation and defect formation results, the Reddy tool design is most suitable for high and low rotational speeds, the conical Shoulder tool at no tilt is most suitable for medium rotational speeds, the conical shoulder tool at a two degree tool tilt is most suitable for medium rotational speeds, the... , M.Ing. (Mechanical Engineering)
- Full Text:
- Authors: Reddy, Randall Dwain
- Date: 2015
- Subjects: Friction stir welding , Dissimilar welding , Aluminum
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213567 , uj:21169
- Description: Abstract: Friction Stir Welding (FSW) is regarded as the most significant development in joining over the past two decades. In FSW, process parameters and tool geometry play a fundamental role in obtaining desirable mechanical properties and microstructures in the welded zone. The tool geometry plays an important role in producing sound friction stir welds. Tool designs are however, generally propriety to individual researchers and only limited information is available in open literature. There are however, continuous efforts to understand the material flow and the influence that the FSW tool design has on the friction stir welded material. Within industries that use various welding techniques it well known that FSW is particularly suited for the welding of aluminium; there is great potential for FSW of copper. Given the limited supply, high cost, copper theft and commercial demand associated with copper, engineers and scientists will either attempt to reduce the quantity of copper consumed by industries or alternatively replace copper with a substitute metal that exhibits similar attributable properties. On account of the limited supply and consequently the high cost associated with copper and copper alloys; the need to join aluminium and copper and its’ alloys is anticipated to increase in the near future. FSW of dissimilar alloys/metals has attracted extensive research interest due to potential engineering prominence and inherent problems associated with conventional welding methods. This research identifies the choice of suitable tool designs and process parameters to produce sound dissimilar friction stir welds of 5754 aluminium and C11000 copper. This research focuses primarily on determining the effect of FSW process parameters on the forces experienced by the FSW tool and the relationship that this has on the electrical conductivity properties of the friction stir dissimilar weld. The experimental work was performed by completing dissimilar friction stir welds on 3 mm thick butt welds of the two materials by means of an I-stir FSW platform. During the experimental work, the rotational speed was varied between 600 and 1200 rpm in intervals on 300 related to low, medium and high rotational speeds respectively and four different FSW tool geometries were tested. The first tool was a new design with a unique shoulder topography and a cylindrical pin named the “Reddy tool”. The second tool was a tool consisted of a concave shoulder and conical pin. Tests were performed using the second tool at a 0 degree tilt and at a 2 degree tilt relative to the work-piece. The third tool consisted of a concave shoulder and cylindrical pin. The forth tool design consisted of a flat shoulder and a cylindrical pin. This research forms part of the initial experimental work to determine the forces and electrical resistance of dissimilar friction stir welds of aluminium and copper by employing different tool shoulder designs. The welds were characterised through visual inspection, weld defect and material flow analysis, microstructural evaluation, electrical resistance measurements and tool forces and tool torque analysis. Microstructural evaluation results revealed complex flow patterns of copper and aluminium material. Lamellae structures composed of copper particles with a streamline shape and continuous aluminium strips were present. Some evidence of dynamic recrystallization was observed in the nugget of the defect free welds. Based on material flow evaluation and defect formation results, the Reddy tool design is most suitable for high and low rotational speeds, the conical Shoulder tool at no tilt is most suitable for medium rotational speeds, the conical shoulder tool at a two degree tool tilt is most suitable for medium rotational speeds, the... , M.Ing. (Mechanical Engineering)
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Microstructural characterization of friction stir lap welds of aluminium incorporated with titanium carbide
- Abegunde, O. O., Akinlabi, Esther Titilayo, Madyira, D. M.
- 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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- 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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Effect of plunge depth on weld integrity of friction stir welds of dissimilar aluminium and copper
- Ewuola, Oluwatoyin O., Akinlabi, Esther Titilayo, Madyira, Daniel M.
- Authors: Ewuola, Oluwatoyin O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
- Date: 2016
- Subjects: Aluminum , Copper , Friction stir welding , Plunge depth , Lap welds
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93322 , uj:20332 , Citation: Ewuola, O.O., Akinlabi, E.T. & Madyira, D.M. 2016. Effect of plunge depth on weld integrity of friction stir welds of dissimilar aluminium and copper.
- Description: Abstract: This paper presents the effects of plunge depth on the weld integrities of Friction Stir lap welds of aluminium and copper. 3 mm sheets of aluminium and copper were joined using the Friction Stir Welding (FSW) technique. The study focuses on understanding the relationship between the defects and the process parameters. The produced welds were characterized using visual inspection, microstructural evaluation and microhardness profiling. It was found that while all the typical FSW microstructural zones were present in the welds, the sizes of the voids observed in the welds were dependent on the plunge depth employed. Optimization of the processing parameters is in view.
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- Authors: Ewuola, Oluwatoyin O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
- Date: 2016
- Subjects: Aluminum , Copper , Friction stir welding , Plunge depth , Lap welds
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93322 , uj:20332 , Citation: Ewuola, O.O., Akinlabi, E.T. & Madyira, D.M. 2016. Effect of plunge depth on weld integrity of friction stir welds of dissimilar aluminium and copper.
- Description: Abstract: This paper presents the effects of plunge depth on the weld integrities of Friction Stir lap welds of aluminium and copper. 3 mm sheets of aluminium and copper were joined using the Friction Stir Welding (FSW) technique. The study focuses on understanding the relationship between the defects and the process parameters. The produced welds were characterized using visual inspection, microstructural evaluation and microhardness profiling. It was found that while all the typical FSW microstructural zones were present in the welds, the sizes of the voids observed in the welds were dependent on the plunge depth employed. Optimization of the processing parameters is in view.
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Effect of rotational speed on joint inegrity of friction stir lap welded aluminium
- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.
- 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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- 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)
- Full Text:
- 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
- Abegunde, Olayinka O., Akinlabi, Esther Titilayo, Madyira, Daniel M.
- Authors: Abegunde, Olayinka O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
- Date: 2016
- Subjects: Force feedback , Friction stir welding , Heat input , Torque
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93400 , uj:20342 , Citation: Abegunde, O.O., Akinlabi, E.T. & Madyira, D.M. 2016. Force feedback analysis: friction stir welding of aluminium metal matrix composite.
- Description: Abstract: This paper presents the output response parameters (forces feedback, torque and heat input) during friction stir welding of aluminium. The welding was performed on an Intelligent Stir Welding for Industry and Research (ISTIR) Process Development System (PDS) using different rotational and transverse speeds while other input parameters like tool geometry, tilt angle and workpieces configuration were kept constant. The I-STIR FSW platform is capable of recording the force feedback and torque during the welding process and the heat input was calculated using a mathematical relationship. The study reveals the influence of the rotational and transverse speed on the pattern of the output feedback. The reinforcement ceramic particles added to the weld seam during welding also affected the output feedback.
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- Authors: Abegunde, Olayinka O. , Akinlabi, Esther Titilayo , Madyira, Daniel M.
- Date: 2016
- Subjects: Force feedback , Friction stir welding , Heat input , Torque
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/93400 , uj:20342 , Citation: Abegunde, O.O., Akinlabi, E.T. & Madyira, D.M. 2016. Force feedback analysis: friction stir welding of aluminium metal matrix composite.
- Description: Abstract: This paper presents the output response parameters (forces feedback, torque and heat input) during friction stir welding of aluminium. The welding was performed on an Intelligent Stir Welding for Industry and Research (ISTIR) Process Development System (PDS) using different rotational and transverse speeds while other input parameters like tool geometry, tilt angle and workpieces configuration were kept constant. The I-STIR FSW platform is capable of recording the force feedback and torque during the welding process and the heat input was calculated using a mathematical relationship. The study reveals the influence of the rotational and transverse speed on the pattern of the output feedback. The reinforcement ceramic particles added to the weld seam during welding also affected the output feedback.
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