Microhardness and Microstructure of Hot Extrusion Parameters in Direct Recycling of Aluminium Chip (AA 6061) by ANOVA Method

• Published in: Journal of physics. Conference series Vol. 1150; no. 1; pp. 12069 - 12078
• Main Authors: Rady, Mohammed H, Sukri Mustapa, Mohd, Shamsudin, S, Lajis, M A, Wagiman, A
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2019
• Subjects: Aluminum; Design analysis; Design of experiments; Extrusion dies; Factorial design; Grain size; Heating; Hot extrusion; Microhardness; Microstructural analysis; Microstructure; Process parameters; Recycling
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1150/1/012069

Microhardness and microstructure become a main concern in direct recycling of metal chips. Products by solid-state recycling of aluminum chips in hot extrusion process are controlled by many factors such as die geometry, extrusion ratio, temperature related parameters and etc. in which each of them could influence the extrudate's quality. This study investigates the effects of preheating temperature and preheating time on the response variable (microhardness and microstructure). The various settings of preheating temperature were taken as 450 °C, 500 °C, and 550 °C. On the other hand, three values of preheating time were chosen (1, 2, 3) hours. The influences of the process parameters (preheating temperature and time) were analyzed using Design of Experiments (DOE) approach whereby full factorial design with center point analysis was adopted. The total runs were 11 and they comprise of two factors of full factorial design with 3 center points. The results found that the preheating temperature is more important to be controlled rather than the preheating time in analysis of microhardness and decreasing of temperature led to the high microhardness. The profile extruded at 450 °C and 1 hr had gained the optimum microhardness and it can be concluded that setting temperature at 550 °C for 3 hour resulted in the highest responses for average of grain sizes in analysis of microstructure.