Analysis of welding performance thin material aluminium alloy 1100 series using Bobbin friction stir welding

Bobbin Friction Stir Welding (BFSW) is a solid-state welding technique combining heat and pressure to complete the process. With the advancement of technology, many industries opt for thin materials in their production thus making the joining process more difficult especially when involving BFSW tec...

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Bibliographic Details
Main Author: Mohd Kassim, Mohammad Khairul Azmi
Format: Thesis
Language:English
English
Published: 2023
Subjects:
Online Access:http://eprints.utem.edu.my/id/eprint/28267/1/Analysis%20of%20welding%20performance%20thin%20material%20aluminium%20alloy%201100%20series%20using%20Bobbin%20friction%20stir%20welding.pdf
http://eprints.utem.edu.my/id/eprint/28267/2/Analysis%20of%20welding%20performance%20thin%20material%20aluminium%20alloy%201100%20series%20using%20Bobbin%20friction%20stir%20welding.pdf
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Summary:Bobbin Friction Stir Welding (BFSW) is a solid-state welding technique combining heat and pressure to complete the process. With the advancement of technology, many industries opt for thin materials in their production thus making the joining process more difficult especially when involving BFSW technique. This is due to lack of study focusing on joining thin materials using BFSW technique. Therefore, this study is carried out to investigate the welding performance of thin material Alumium Alloy 1100 series using fixed BFSW process. 3mm thickness of Aluminium Alloy 1100 series is used in this study. 2 types of tool designs are used to ensure that the joining can be achieved with zero defect. Both tools are used in a pilot test to identify the suitable range of process parameter and the best tool is selected for this study. The test results showed that the tool having two convex angles (Tool 2) produced better joining compared to the other one. Therefore, Tool 2 is selected as the main tool for the rest of this study. There are only 2 process parameters used in this study which are rotational speed and welding speed. Based on the pilot test results, the suitable range of parameters used in this study are 1500 – 1600 rpm for rotational speed and 150 – 210 mm/min for welding speed. Design of Experiment (DoE) software is used in designing the study model. After the experiment is conducted, it is found out that the rate of error of this study model is below 10% and all the analysis by DoE can be accepted. During the process, 4 different responses were recorded which were temperature, vibration, current and force. Then, all the welded parts were cut for the tensile and microhardness testing. After that, the welded parts were divided into 3 different areas which were Entry Side (EN), Middle Side (MD), and Exit Side (EX). Each area was analyzed based on the best and worst mechanical properties for joining. The analysis showed that the EN of the welded parts had higher tensile and microhardness strength, while EX showed the weakest tensile and microhardness strength. Apart from that, Advancing Side (AS) had higher temperature generation compared to Retreating Side (RS) due to the tool direction. Then, it was also found that all the vibration, current and force were unstable at the EN and becoming more stable towards the EX. This is believed to be due to heat generation that occurs towards the end of the material. Last but not least, all the joining specimens were analyzed based on the microstructure of each area focusing on Heat Affected Zone (HAZ) and Stir Zone (SZ). The founding showed that HAZ encompassed bigger microstructure area compared to the SZ due to the higher heat experience without any mechanical movement. Due to that, there were a few defects that occurred on the welded parts which were incomplete joining and keyhole defects. All of these findings show that the difficulties of joining thin materials using BFSW technique can be solved by maintaining the temperature within acceptable value during the process, lowering the vibrancy during the process, and using suitable tool design to transport the soft material from AS to RS during the process.