Reinforcement of aluminium AA1100-MIG welds using copper powder
- Authors: Abima, Cynthia Samuel
- Date: 2017
- Subjects: Aluminum alloys - Welding , Welded joints - Reliability , Copper - Welding , Shielded metal arc welding , Gas tungsten arc welding
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269571 , uj:28637
- Description: M.Ing. (Mechanical Engineering) , Abstract: Metal matrix composites have been used in recent times to achieve better mechanical properties of materials and improved general performance of welded structures. Metal Inert Gas (MIG) welding also known as Gas Metal Arc welding (GMAW) is an arc-welding process, which joins metals by heating them with an arc between a continuously fed solid electrode and the work piece. Aluminium and its alloys provides unique properties which makes it one of the most attractive metallic, economical, versatile material for a broad range of uses in engineering applications, such as aerospace, automobile and mineral processing industries. Against this background, aluminium is not suitable for all engineering applications, and it sometimes requires some degree of reinforcement, particularly in a corrosive environment and/or at elevated temperatures. This study focuses on ascertaining the integrity of MIG welded pure aluminium reinforced with copper powder at the weld zone. Material characterizations of the aluminium (Al) and copper (Cu) metal matrix composites produced via the MIG welding process were conducted. The pure aluminium, AA1100 sheets were machined to a 45o v-grooved shape, and then filled with copper powder particles and welded. The welded samples were characterised by performing mechanical tests (tensile testing using the Zwick Roell 2250 tensile machine and microhardness profiling using a digital Vickers microhardness testing machine) and microstructural investigation via the scanning electron microscope (SEM), the energy-dispersive spectroscopy (EDS) and optical microscope. This was followed by X-ray diffraction analysis (XRD), and corrosion test by electrochemical polarization method. The results revealed that the addition of copper powder significantly increased the hardness property of the welds, as the welds with copper powder particles reinforcement showed higher hardness values when compared to those without the copper powder particle reinforcement. The highest tensile strength was obtained from the copper reinforced sample. Furthermore, the microstructures revealed finer grain structures for the reinforced samples. The samples with reinforcement also exhibited better corrosion properties. It was therefore, concluded that the aluminium (Al) and copper (Cu) metal matrix composite welded via MIG welding produced better mechanical properties, as well as increased corrosion resistance behaviour, and it can definitely be recommended for typical aerospace applications
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- Authors: Abima, Cynthia Samuel
- Date: 2017
- Subjects: Aluminum alloys - Welding , Welded joints - Reliability , Copper - Welding , Shielded metal arc welding , Gas tungsten arc welding
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269571 , uj:28637
- Description: M.Ing. (Mechanical Engineering) , Abstract: Metal matrix composites have been used in recent times to achieve better mechanical properties of materials and improved general performance of welded structures. Metal Inert Gas (MIG) welding also known as Gas Metal Arc welding (GMAW) is an arc-welding process, which joins metals by heating them with an arc between a continuously fed solid electrode and the work piece. Aluminium and its alloys provides unique properties which makes it one of the most attractive metallic, economical, versatile material for a broad range of uses in engineering applications, such as aerospace, automobile and mineral processing industries. Against this background, aluminium is not suitable for all engineering applications, and it sometimes requires some degree of reinforcement, particularly in a corrosive environment and/or at elevated temperatures. This study focuses on ascertaining the integrity of MIG welded pure aluminium reinforced with copper powder at the weld zone. Material characterizations of the aluminium (Al) and copper (Cu) metal matrix composites produced via the MIG welding process were conducted. The pure aluminium, AA1100 sheets were machined to a 45o v-grooved shape, and then filled with copper powder particles and welded. The welded samples were characterised by performing mechanical tests (tensile testing using the Zwick Roell 2250 tensile machine and microhardness profiling using a digital Vickers microhardness testing machine) and microstructural investigation via the scanning electron microscope (SEM), the energy-dispersive spectroscopy (EDS) and optical microscope. This was followed by X-ray diffraction analysis (XRD), and corrosion test by electrochemical polarization method. The results revealed that the addition of copper powder significantly increased the hardness property of the welds, as the welds with copper powder particles reinforcement showed higher hardness values when compared to those without the copper powder particle reinforcement. The highest tensile strength was obtained from the copper reinforced sample. Furthermore, the microstructures revealed finer grain structures for the reinforced samples. The samples with reinforcement also exhibited better corrosion properties. It was therefore, concluded that the aluminium (Al) and copper (Cu) metal matrix composite welded via MIG welding produced better mechanical properties, as well as increased corrosion resistance behaviour, and it can definitely be recommended for typical aerospace applications
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Effect of post-weld heat treatment on the evolving properties of P355NL1
- Authors: Mamabolo, Masemenya
- Date: 2017
- Subjects: Welding , Shielded metal arc welding , Stainless steel - Welding , Gas tungsten arc welding , Residual stresses
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269810 , uj:28667
- Description: M.Ing. (Mechanical Engineering) , Abstract: Post Weld Heat Treatment (PWHT) in the form of stress relieving consists of heating the steel to a temperature below the critical range to relieve the stresses resulting from welding. The mechanical and microscopic properties may also be affected during this process. The study of the effects of Post-Weld Heat Treatment on the evolving properties of the fine-grain carbon alloy steel P355NL1 was conducted, and presented in this report. The study focused on the mechanical and metallurgical properties of the material. The plates used were 6 mm thick with a length of 350 mm and a width of 150 mm; and they were welded using the Gas Metal Arc Welding (GMAW) method. After the welding; PWHT was performed on the plates, using a furnace with the specified temperature and time. A total of four plates were studied; where three plates underwent the same PWHT method, apart from the cooling methods. There was a control sample wherein the plate did not undergo any PWHT; the second plate was furnace-cooled; the third was air-cooled; while the fourth plate was water-cooled. A comparative study was done on the P355NL1 plates, using three testing methods, namely: the tensile test; the microstructure examination; and the microhardness test to investigate how the different cooling methods had affected the properties of the steel, compared to the control as the basis point of comparison. The hardness properties of air and furnace cooled P355NL1 steel decreased compared to the without sample. The tensile strength properties of the sample had shown some improvement for the water-cooled plate; the furnace and air-cooled samples had, however, decreased in terms of their tensile strength. The yield strength properties of the samples revealed similar findings. Although the metallurgical structures revealed different concentrations of darker (pearlite) and lighter (ferrite) grains in the base metal, the overall study showed that there were no significant changes in the microstructure, however, the cooling media employed can be recommended as required for tailored applications.
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- Authors: Mamabolo, Masemenya
- Date: 2017
- Subjects: Welding , Shielded metal arc welding , Stainless steel - Welding , Gas tungsten arc welding , Residual stresses
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269810 , uj:28667
- Description: M.Ing. (Mechanical Engineering) , Abstract: Post Weld Heat Treatment (PWHT) in the form of stress relieving consists of heating the steel to a temperature below the critical range to relieve the stresses resulting from welding. The mechanical and microscopic properties may also be affected during this process. The study of the effects of Post-Weld Heat Treatment on the evolving properties of the fine-grain carbon alloy steel P355NL1 was conducted, and presented in this report. The study focused on the mechanical and metallurgical properties of the material. The plates used were 6 mm thick with a length of 350 mm and a width of 150 mm; and they were welded using the Gas Metal Arc Welding (GMAW) method. After the welding; PWHT was performed on the plates, using a furnace with the specified temperature and time. A total of four plates were studied; where three plates underwent the same PWHT method, apart from the cooling methods. There was a control sample wherein the plate did not undergo any PWHT; the second plate was furnace-cooled; the third was air-cooled; while the fourth plate was water-cooled. A comparative study was done on the P355NL1 plates, using three testing methods, namely: the tensile test; the microstructure examination; and the microhardness test to investigate how the different cooling methods had affected the properties of the steel, compared to the control as the basis point of comparison. The hardness properties of air and furnace cooled P355NL1 steel decreased compared to the without sample. The tensile strength properties of the sample had shown some improvement for the water-cooled plate; the furnace and air-cooled samples had, however, decreased in terms of their tensile strength. The yield strength properties of the samples revealed similar findings. Although the metallurgical structures revealed different concentrations of darker (pearlite) and lighter (ferrite) grains in the base metal, the overall study showed that there were no significant changes in the microstructure, however, the cooling media employed can be recommended as required for tailored applications.
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Surface engineering : laser metal deposition of titanium alloy Grade 5 and tungsten
- Authors: Ndou, Ndivhuwo
- Date: 2017
- Subjects: Lasers - Industrial applications , Gas tungsten arc welding , Mechanical wear , Pulsed laser deposition , Titanium alloys - Fatigue
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/269875 , uj:28675
- Description: D.Phil. (Mechanical Engineering) , Abstract: Titanium alloy Grade 5 (Ti6Al4V) has attracted the interest of the engineering community, because of its excellent physical and mechanical properties. Due to its low density, superior quality at high temperature and good corrosion resistance, Ti6Al4V alloy is used in the aerospace industry. The alloy has also been applied in many areas, such as sport, marine, the chemical industry, the automotive industry and the biomedical field – due to its excellent corrosion resistance in a corrosive environment or medium. Because of the poor wear-resistance properties exhibited by the alloy, five weight percent of tungsten (W) was agglomerated with it, this percentage weight addition of tungsten was optimised, in order to improve its surface properties in this research study. The tungsten is selected due to its superior strength, creep resistance, and structural stability at elevated temperatures. Trial experiments were first conducted with the two powders, Ti6Al4V and W (Ti6Al4V+W). The parameters with good laser deposition process were selected for the preliminary studies. The relationships between the process parameters on the material characterizations were thoroughly investigated. Design Expert 9 software was used to validate the experimental results. In the design of the experiment, the Response Surface Methodology (RSM) was used to determine the required process parameters standard order and the leverage, as well as the response to the input factors. The model was validated to establish the variations between the predicted value and the actual value. The laser deposited Ti6Al4V+W specimens were characterized through the evolving microstructures, dry sliding wear, corrosion, microhardness and x-Ray diffraction.
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- Authors: Ndou, Ndivhuwo
- Date: 2017
- Subjects: Lasers - Industrial applications , Gas tungsten arc welding , Mechanical wear , Pulsed laser deposition , Titanium alloys - Fatigue
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/269875 , uj:28675
- Description: D.Phil. (Mechanical Engineering) , Abstract: Titanium alloy Grade 5 (Ti6Al4V) has attracted the interest of the engineering community, because of its excellent physical and mechanical properties. Due to its low density, superior quality at high temperature and good corrosion resistance, Ti6Al4V alloy is used in the aerospace industry. The alloy has also been applied in many areas, such as sport, marine, the chemical industry, the automotive industry and the biomedical field – due to its excellent corrosion resistance in a corrosive environment or medium. Because of the poor wear-resistance properties exhibited by the alloy, five weight percent of tungsten (W) was agglomerated with it, this percentage weight addition of tungsten was optimised, in order to improve its surface properties in this research study. The tungsten is selected due to its superior strength, creep resistance, and structural stability at elevated temperatures. Trial experiments were first conducted with the two powders, Ti6Al4V and W (Ti6Al4V+W). The parameters with good laser deposition process were selected for the preliminary studies. The relationships between the process parameters on the material characterizations were thoroughly investigated. Design Expert 9 software was used to validate the experimental results. In the design of the experiment, the Response Surface Methodology (RSM) was used to determine the required process parameters standard order and the leverage, as well as the response to the input factors. The model was validated to establish the variations between the predicted value and the actual value. The laser deposited Ti6Al4V+W specimens were characterized through the evolving microstructures, dry sliding wear, corrosion, microhardness and x-Ray diffraction.
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Characterization of TIG and MIG hybrid welding of type - 304 austenitic stainless steel
- Authors: Ogundimu, Emmanuel Olusegun
- Date: 2017
- Subjects: Gas tungsten arc welding , Stainless steel - Welding , Austenitic stainless steel - Welding , Welding
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242297 , uj:24987
- Description: M.Ing. (Mechanical Engineering) , Abstract: Stainless steel is a member of iron based alloys with a good corrosion resistance property. Due to this good quality, stainless steel plates are increasingly used for building constructions materials food processing and kitchen equipment. Austenitic stainless steels are one of the best choices, as they combine noble corrosion performance and mechanical properties. Due to low carbon percentage in austenitic stainless steel, intergranular corrosion can be controlled. The use of stainless steels is imperative. In fact, the numerous applications of type 304 austenitic stainless steel make it omnipresent in our daily life. This research work is aimed to establish optimized process parameters that will result in defect-free weld joint. In this research work, studies were conducted on the material characterization of type 304 austenitic stainless steel hybrid weld produced by Tungsten inert gas (TIG) and Metal inert gas (MIG) welding Processes. The processes were carried out in three phases. In the first phase of welding, two similar 304 stainless steel plates were welded by MIG welding using welding current of 130A and 170A, , the second phase was produced by TIG welding using the currents of 130/150A, while third phase welding was an hybrid TIG-MIG welding produced at currents of 130/150 and 170/190A respectively. The effects of welding current and welding process on the mechanical properties of the welded joints were investigated for all the three types of butt weld joint. Optical microscopic analysis were done on the heat affected zone and weld zone to assessed the effect of the welding parameters and the welding process on the weld quality. 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...
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- Authors: Ogundimu, Emmanuel Olusegun
- Date: 2017
- Subjects: Gas tungsten arc welding , Stainless steel - Welding , Austenitic stainless steel - Welding , Welding
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242297 , uj:24987
- Description: M.Ing. (Mechanical Engineering) , Abstract: Stainless steel is a member of iron based alloys with a good corrosion resistance property. Due to this good quality, stainless steel plates are increasingly used for building constructions materials food processing and kitchen equipment. Austenitic stainless steels are one of the best choices, as they combine noble corrosion performance and mechanical properties. Due to low carbon percentage in austenitic stainless steel, intergranular corrosion can be controlled. The use of stainless steels is imperative. In fact, the numerous applications of type 304 austenitic stainless steel make it omnipresent in our daily life. This research work is aimed to establish optimized process parameters that will result in defect-free weld joint. In this research work, studies were conducted on the material characterization of type 304 austenitic stainless steel hybrid weld produced by Tungsten inert gas (TIG) and Metal inert gas (MIG) welding Processes. The processes were carried out in three phases. In the first phase of welding, two similar 304 stainless steel plates were welded by MIG welding using welding current of 130A and 170A, , the second phase was produced by TIG welding using the currents of 130/150A, while third phase welding was an hybrid TIG-MIG welding produced at currents of 130/150 and 170/190A respectively. The effects of welding current and welding process on the mechanical properties of the welded joints were investigated for all the three types of butt weld joint. Optical microscopic analysis were done on the heat affected zone and weld zone to assessed the effect of the welding parameters and the welding process on the weld quality. 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...
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