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Characterisation of dissimilar friction stir welded 7075 and 6101 aluminum alloys

Microstructural characterizations of dissimilar friction stir welds

  • 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

  • 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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Effect of punch diameters on shear extrusion of 6063 aluminium alloy

  • Authors: Erinosho, M. F. , Ajiboye, J. S. , Akinlabi, Esther Titilayo
  • Date: 2015-07-01
  • Subjects: Aluminum alloys , Shear extrusion , Punch diameters
  • Type: Article
  • Identifier: uj:5121 , http://hdl.handle.net/10210/14079
  • Description: This paper reports the effect of punch diameters on the shear extrusion of 6063 Aluminium alloy. During the shear extrusion process, Aluminium billets of considerable diameter 30 mm and height 25 mm were inserted in a die hole and different punches of diameter 12 mm, 14 mm, 16 mm and 18 mm respectively were allowed to come in contact to perform the shear operation. The setup took place under a hydraulic press with maximum capacity of 600 kN. This work is aimed at studying the selection of the optimum punch diameter for shear extrusion using local groundnut oil as the lubricant. Different extrusion pressures were measured and the punch with a diameter of 18 mm gives the highest load of 77.7 kN while the punch with a diameter of 12 mm gives the lowest load of 51.2 kN. An indication shows that, an increase in the punch diameters led to an increase in the height of the extrudates and this in turn reduces the stress induced.
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Numerical simulation of solute redistribution during transient liquid phase bonding processing for Al-Cu alloy"

  • Authors: Jiao, Y. , Jen, Tien-Chien , Jiao, Yuning
  • Date: 2011
  • Subjects: Numerical simulation , Solute redistribution , Transient liquid phase , Aluminum alloys , Copper alloys
  • Type: Article
  • Identifier: uj:5246 , ISSN 1040-7782 , http://hdl.handle.net/10210/14852
  • Description: A one-dimensional mathematical model is developed to predict the solute redistribution during the transient liquid phase (TLP) bonding process for Al-Cu alloy. The macroscopic solute diffusion in the liquid and the solid as well as for the solid transformation to the liquid because of the solute macrosegregation are considered in this study. The effects of holding temperatures and the interlayer thickness on the holding time, remelting layer thickness, and the mush zone thickness of the TLP bonding process are investigated. It is shown numerically that the holding time, the holding temperature, and the interlayer thickness influence the solute distribution strongly, which in turn influence the mush zone thickness significantly.
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Microstructure and mechanical characterization of aluminum seamless tubes produced by friction stir back extrusion

Friction stir spot welding of dissimilar materials-an overview

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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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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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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