Ruhaizat, Nasha Emieza (2023) The analysis of life cycle assessment and life cycle costing in direct recycling hot press forging of aluminium AA7075. Doctoral thesis, Universiti Tun Hussein Onn Malaysia.

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Abstract

Aluminium is the second largest used metal after iron which contributes a large impact on the environment. Recycling is a well-known method for mitigating the environmental impacts of aluminium production. However, the conventional recycling approach requires high energy consumption for remelting scrap and involves many operations which can increase the cost. Therefore, solid state direct recycling has been implemented to reduce energy and material consumption. It is essential to produce an aluminium billet that possesses superior functional performance as well as minimizes the environmental impact and economic cost. For this purpose, this study investigated the effect of the hot press forging (HPF) process parameter on the functional performance of recycled AA7075 billet. In addition, the analysis of life cycle assessment (LCA) and life cycle costing (LCC) approach were used to compare the environmental impact and economic cost of aluminium recycling routes between remelting and HPF process. The response surface methodology (RSM) and the desirability function were implemented in this study to optimise the aluminium recycling condition of AA7075 aluminium alloys. The study of DR-HPF shows that the optimum parameter for AA7075 aluminium alloy based on statistical optimization by RSM is 480°C forging temperature and 85.56 minutes holding time with 0.780 desirabilities. The maximum process parameter of recycled specimens is comparable to the theoretical ASM AA7075. Compared to the remelting process, the HPF method significantly reduces GWP and manufacturing costs by up to 85.26 % and 82.46 %, respectively. The potential of the HPF process as an alternative approach in terms of environmental impact reduction and functional performance offered for recycling AA7075 aluminium scrap has been demonstrated

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