Thuong, Nguyen Van
(2014)
Effect Of Secondary Plastic Deformation On The Microstructures And Mechanical Properties Of Cast Ai-7Si-Mg Alloy.
Masters thesis, Perpustakaan Hamzah Sendut.
Abstract
The purpose ofthis research is to study microstructure and hardness of AI-7SiMg
alloy under different cooling slope casting conditions and equal channel angular
pressing (ECAP). The effect of cooling slope casting method with varying variables,
such as pouring temperature (625°C - 640°C - 660°C - 680°C), cooling slope length
(150 mm - 250 mru- 350 mm) and cooling slope temperature (room temperature -
200°C - 400°C) and conventional casting method are investigated. The as-cast alloys
and as-ECAPed alloys were analyzed based on Differential Scanning Calorimetry, Xray
fluorescence, microstructures, hardness, X-ray Diffraction pattern, wear resistance,
Secondary Electron Microscope and Energy Dispersive X-ray. Microstructure of
conventional cast alloy cast at pouring temperature of 640°C was coarse and almost
dendrite the structure. However, uniform, fine and globular microstructure could be
obtained from cooling slope casting with pouring temperature range of 625°C - 660°C,
cooling slope length range of 150 mm - 350 mm and slope temperature ranging from
room temperature to 200°C_ This is due to copious nucleation occurred on slope
surface and these nuclei were then detached due to the force convection during pouring
process.
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