الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In the present investigation, feedstocks of AA6063 wrought aluminum alloy, with a thixotropic microstructure, were prepared using low superheat casting (LSC) were investigated. The effects of pouring temperature, mould type (material) and the grain refining using Al-5%Ti-1%B master alloy on the microstructural characteristics and mechanical behavior of AA6063 wrought Al alloy were studied. An optimization of the aforementioned parameters was carried out using Taguchi’s approach. Moreover, the analysis of variance (ANOVA) statistical approach was carried out to clarify the level of significance of the parameters and their optimum combination. Grain refinement process is one of the most applicable methods in improving mechanical behavior of aluminium based alloys.
The results revealed that the grain refining has the greatest influence on both the average grain size and shape factor of the primary α-Al grains, and on the mechanical properties of AA 6063 feedstocks. Feedstocks poured using the grain refiner exhibited lower size and higher shape factor of α-Al grains and also higher hardness and the tensile elongation than those poured without grain refining. Increasing the pouring temperature slightly increases the average size while reduces the average shape factor of the primary α-Al grains, and also reducing the hardness and tensile elongation of AA6063 feedstocks. Feedstocks poured in the copper mould exhibited the lowest average size and highest average shape factor of primary α-Al when compared with feedstocks poured in low carbon steel and stainless steel moulds. The optimum microstructural characteristics and suitable for thixoforming was exhibited for grain refined AA6063 feedstocks poured in the copper mould at 665 oC, and also has the highest hardness compared with the other feedstocks with and without grain refining.
17
CHAPTER 1
INTRODUCTIONIn the present investigation, feedstocks of AA6063 wrought aluminum alloy, with a thixotropic microstructure, were prepared using low superheat casting (LSC) were investigated. The effects of pouring temperature, mould type (material) and the grain refining using Al-5%Ti-1%B master alloy on the microstructural characteristics and mechanical behavior of AA6063 wrought Al alloy were studied. An optimization of the aforementioned parameters was carried out using Taguchi’s approach. Moreover, the analysis of variance (ANOVA) statistical approach was carried out to clarify the level of significance of the parameters and their optimum combination. Grain refinement process is one of the most applicable methods in improving mechanical behavior of aluminium based alloys.
The results revealed that the grain refining has the greatest influence on both the average grain size and shape factor of the primary α-Al grains, and on the mechanical properties of AA 6063 feedstocks. Feedstocks poured using the grain refiner exhibited lower size and higher shape factor of α-Al grains and also higher hardness and the tensile elongation than those poured without grain refining. Increasing the pouring temperature slightly increases the average size while reduces the average shape factor of the primary α-Al grains, and also reducing the hardness and tensile elongation of AA6063 feedstocks. Feedstocks poured in the copper mould exhibited the lowest average size and highest average shape factor of primary α-Al when compared with feedstocks poured in low carbon steel and stainless steel moulds. The optimum microstructural characteristics and suitable for thixoforming was exhibited for grain refined AA6063 feedstocks poured in the copper mould at 665 oC, and also has the highest hardness compared with the other feedstocks with and without grain refining.
17
CHAPTER 1
INTRODUCTIONIn the present investigation, feedstocks of AA6063 wrought aluminum alloy, with a thixotropic microstructure, were prepared using low superheat casting (LSC) were investigated. The effects of pouring temperature, mould type (material) and the grain refining using Al-5%Ti-1%B master alloy on the microstructural characteristics and mechanical behavior of AA6063 wrought Al alloy were studied. An optimization of the aforementioned parameters was carried out using Taguchi’s approach. Moreover, the analysis of variance (ANOVA) statistical approach was carried out to clarify the level of significance of the parameters and their optimum combination. Grain refinement process is one of the most applicable methods in improving mechanical behavior of aluminium based alloys.
The results revealed that the grain refining has the greatest influence on both the average grain size and shape factor of the primary α-Al grains, and on the mechanical properties of AA 6063 feedstocks. Feedstocks poured using the grain refiner exhibited lower size and higher shape factor of α-Al grains and also higher hardness and the tensile elongation than those poured without grain refining. Increasing the pouring temperature slightly increases the average size while reduces the average shape factor of the primary α-Al grains, and also reducing the hardness and tensile elongation of AA6063 feedstocks. Feedstocks poured in the copper mould exhibited the lowest average size and highest average shape factor of primary α-Al when compared with feedstocks poured in low carbon steel and stainless steel moulds. The optimum microstructural characteristics and suitable for thixoforming was exhibited for grain refined AA6063 feedstocks poured in the copper mould at 665 oC, and also has the highest hardness compared with the other feedstocks with and without grain refining.