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Effects of hot press forging parameter and life cycle assessment in direct recycling of AA6061 aluminium

Yusuf, Nur Kamilah (2017) Effects of hot press forging parameter and life cycle assessment in direct recycling of AA6061 aluminium. PhD thesis, Universiti Tun Hussein Onn Malaysia.


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Industrial processes have led to global warming by carbon dioxide emissions and considerable amounts of solid waste. Meltless recycling technique have been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press forging was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to investigate the effects of parameter to the functional performance of the technique and analysed the environmental impacts with the corresponding remelting method. For this purpose, recycling aluminium chips AA6061 by utilizing hot press forging process with full factorial 3^2 design of experiment (DOE) which consists of three operating temperature, Ts and three holding time, ts. Response surface methodology (RSM) was utilized for responses optimization and central composite design (CCD) was applied in designing the experiments to evaluate the effects of hot press forging parameter to three responses; ultimate tensile strength (UTS), elongation to failure (ETF) and global warming potential (GWP). The maximum mechanical properties and surface integrity of recycled chip (T1-temper) are remarkably comparable with theoretical AA6061 T4-temper where the value of UTS and microhardness exhibited greater. As the desired mechanical properties of forgings can be obtained only by means of a final heat treatment, T5-temper; aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6. Response surface optimization shows the suggested optimal hot press forging parameters in this research. Life cycle assessment (LCA) of direct recycling hot press forging process were evaluated and the GWP value of hot press forging routes gives a notable environmental impact when it significantly reduced as compared to conventional (melting) routes.

Item Type: Thesis (PhD)
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 28 May 2018 06:33
Last Modified: 28 May 2018 06:33
URI: http://eprints.uthm.edu.my/id/eprint/10008
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