Azlan Ahmad

Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity

Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press 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 prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (Ts = 430, 480, and 530 °C) and holding times (ts = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at Ts = 530 °C and ts = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained 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, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices.

On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

Life Cycle Assessment on the Effects of Parameter Setting in Direct Recycling Hot Press Forging of Aluminum

Metallic material processing plays a significant role in terms of global environmental impact which contributes to the climate change phenomena that is a serious international environmental concern and the subject of much research and debate. Thus, energy-and resource-efficient strategies in the metal shaping technology domain need to be identified urgently. A frequent theme in the debates that surround waste and resources management is the extent to which the recycling of metallic materials offers genuine benefits to the environment. Solid state recycling techniques allow the manufacture of high density aluminum alloy parts directly from production scrap. In this paper the environmental impacts associated with ‘meltless’ scrap processing routes through hot press forging process with varying parameter has been studied. A comparative analysis has been performed, with different operating temperature and holding time of direct recycling hot press forging process AA6061 aluminum chip. The importance of an environmental performance analysis that included both parameter setting was discussed and highlighted throughout the paper. Finally, the application of the proposed parameter setup has resulted in the setting up of an eco-process. Indeed, LCA study on recycling (solid-state) are recommended as well it gives a noteworthy benefit to the environment and to fill the knowledge gap.

Conjectured the Behaviour of a Recycled Metal Matrix Composite (MMC–AlR) Developed through Hot Press Forging by Means of 3D FEM Simulation

Melting aluminium waste to produce a secondary bulk material is such an energy-intensive recycling technique that it also indirectly threatens the environment. Hot press forging is introduced as an alternative. Mixing the waste with another substance is a proven practice that enhances the material integrity. To cope with the technology revolution, a finite element is utilised to predict the behaviour without a practical trial. Utilising commercial software, DEFORM 3D, the conjectures were demonstrated scientifically. The flow stress of the material was modified to suit the material used in the actual experiment. It is acknowledged that the stress–strain had gradually increased in each step. Due to the confined forming space, the temperature decreased by ~0.5% because the heat could not simply vacate the area. A reduction of ~10% of the flesh observed in the simulation is roughly the same as in the actual experiment. Above all, the simulation abides by the standards and follows what has been done previously. Through the finite element utilisation, this study forecasted the performance of the recycled composite. The results presented may facilitate improvement of the recycling issue and conserve the environment for a better future.

Integrating Simulation with Experiment for Recycled Metal Matrix Composite (MMC-AlR) Developed through Hot Press Forging

This study proposes of harmonizing the original approach of aluminium alloy recycling through hot press forging. By eradicating the melting phase, most of the waste generation can be significantly reduced. To cope with the technology revolution, the finite element is utilised to predict the material behaviour without practically executing the trial. By employing three-dimensional finite element analysis through DEFORM 3D, the evaluations were demonstrated by simulating the isothermal forging process. The flow stress of the material was modified to adequate with the aluminium-based metal matrix composite used in the actual experiment. To that extent, this study found out that the strain of the workpiece had gradually increased on each step. A reduction of ~10% of the flesh observed in the simulation is roughly the same as existed on the experiment workpiece. Above all, the simulation conducted abides by the standard and follows the actual practice that has been done previously. Through the finite element utilization, this study discussed the performance of the recycled based composite. The result presented here may facilitate improvement in the recycling issue and also conserved the environment for the better future.

Parametric optimisation of heat treated recycling aluminium (AA6061) by response surface methodology

Alternating typical primary aluminium production with recycling route should benefit various parties, including the environment since the need of high cost and massive energy consumption will be ruled out. At present, hot extrusion is preferred as the effective solid-state recycling process compared to the typical method of melting the swarf at high temperature. However, the ideal properties of extruded product can only be achieved through a controlled process used to alter the microstructure to impart properties which benefit the working life of a component, which also known as heat treatment process. To that extent, this work ought to investigate the effect of extrusion temperature and ageing time on the hardness of the recycled aluminium chips. By employing Analysis of Variance (ANOVA) for full factorial design with centre point, a total of 11 runs were carried out randomly. Three dissimilar extrusion temperatures were used to obtain gear-shape billet. Extruded billets were cut and ground before entering the treatment phase at three different ageing times. Ageing time was found as the influential factor to affect the material hardness, rather than the extrusion temperature. Sufficient ageing time allows the impurity atoms to interfere the dislocation phenomena and yield great hardness. Yet, the extrusion temperatures still act to assist the bonding activities via interparticle diffusion transport matter.