Main thesis title 2021: subtitle if needed. If no subtitle follow instructions in manual
- Authors: Mashinini, Peter Madindwa
- Date: 2015-03
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53340 , vital:45138
- Description: Ti6Al4V alloy usage is increasing due to high demand from the aerospace and automotive industries as well as the field of medical implants. Therefore, identifying the most effective joining technique is critically important to ensure that optimum life can be achieved by welded components. This is especially important for the aerospace industry where fatigue life of the welded joints is vital. This research identified two relatively new joining technologies for Titanium sheet, namely, Friction Stir Welding (FSW),a solid-state process, and Laser Beam Welding (LBW),a fusion joining process. It was therefore vitalto conduct a systematic study of these two processes and compare results to illustrate which process attributes to static and dynamic properties. This investigation was accomplished by varying the process heat input for both FSW and LBW. The main parameters used to control process heat input were rotational-and traverse speed for FSW and laser power and traverse speed for LBW. In FSW, a reaction torque was used to describe the process energy in order to achieve the plasticised material condition. Preliminary work was done to establish the influencing factors for a successful weld which included tool optimisation but process optimisation was not discussed in elaborative detail. In LBW, traverse speed was identified as the critical control parameter to ensure good weld penetration. Weld width was recorded as it showed strong correlation to heat input rates. , Thesis (MA) -- Faculty of Engineering, the Built Environment and Technology, Mechanical Engineering, 2021
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- Date Issued: 2015-03
Process window for friction stir welding of 3 mm titanium (Ti-6AI-4V)
- Authors: Mashinini, Peter Madindwa
- Date: 2010
- Subjects: Friction stir welding , Titanium -- Welding , Welded joints
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9618 , http://hdl.handle.net/10948/1413 , Friction stir welding , Titanium -- Welding , Welded joints
- Description: Friction stir welding was used to join 3 mm Ti-6Al-4V alloy in a butt joint configuration. This research focused on optimization of a tool geometry and the interaction between process parameters and static performance of welded joints. The main parameters varied were tool travel speed and tool rotational speed. The results showed a relationship between heat input as a function of process parameters and static strength. Improved tensile properties correspond to high heat input. The hardness plots revealed an increase in hardness on both the stir zone and heat affected zone despite the small defects on the weld root. The weld microstructure was also evaluated, which showed a variation in microstructure on both the heat affected zone and stir zone in comparison to the parent material. It was also found that the use of MgO as a heat barrier on the backing plate was detrimental to the weld tensile properties of butt-welded plates compared to bead-on-plate welds of which MgO had no influence.
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- Date Issued: 2010