The effect of cooling rate on mechanical and morphological properties of heat treated recycled aluminum alloy from scrap

• Main Author: Aziz, Azim
• Format: Thesis
• Language: English; English
• Published: 2013
• Subjects: T Technology (General); TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utem.edu.my/id/eprint/14621/1/The_Effect_of_cooling_rate_on_mechanical_and_morphological_properties_of_heat_treated_recycled_aluminum_alloy_from_scrap136.pdf; http://eprints.utem.edu.my/id/eprint/14621/7/The%20effect%20of%20cooling%20rate%20on%20mechanical%20and%20morphological%20properties%20of%20heat%20treated%20recycled%20aluminum%20alloy%20from%20scrap.pdf; http://eprints.utem.edu.my/id/eprint/14621/; http://library.utem.edu.my:8000/elmu/index.jsp?module=webopac-d&action=fullDisplayRetriever.jsp&szMaterialNo=0000085493

Aluminum is the most widely used metal in the world of engineering apart from iron due to the combination of mechanical properties making it one of the most versatile of engineering and construction materials, and recycling is one of the best solution to the disposing of the tons of wastes and residue due to spoilt or end of products life. In order to use the recycled material to be turned back into the same product or better, something has to be done to enhance or improve the mechanical properties of the material. The purpose of this study is to investigate the effect of cooling rates on the mechanical and morphological properties of heat treated recycled automotive aluminum alloy scraps where they were first sorted according to a determined classification and were melted and casted, machined to sample size and undergo heat treatment. The samples were then cooled using four different medium, quenched (used engine oil, water and air from fan ) or annealed (left in the oven to slowly cool down to room temperature). Cooling rates for each medium were recorded at intervals and plotted as time vs temperature graph. Characterization on samples before scrap melting, after casted and after cooling process, shows occurence of morphological changes confirming the hypothesis that cooling rates affect the microstructure of the metals being better and finer. Faster cooling rates generated finer grains and uniform distribution of silicon particles. The samples were further tested for impact strength and tensile properties through an izod pendulum impact tester and a universal testing machine. It can be concluded that increasing cooling rate increases thecapability of metal to withstand impact of o.8 J/mm but decreases the tensile stress, strain and modulus E.