| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 105 === In recent years, the development of metal additive manufacturing (MAM) has brought an innovative progress. Through the additive manufacturing process, the material will be stacked in layers, it will not be limited by the complexity of molding. Selective Laser Melting (SLM) technology is the key technology for the current metal manufacturing. It uses laser as the processing heat source, making the metal powder melt and rapidly cooling. SLM process presents great potential applications in the fabrication of complex parts with fine microstructure. In this study, AlSi10Mg alloy powder obtained by gas atomization process is used to study the parameters of SLM process. The effects of objective of this research is to investigate process parameters such as laser power, layer thickness, scanning speed and hatching distance on the relative density on the object. We then compare the microstructure through the SLM process and mechanical properties before and after heat treatment to determine the appropriate process parameters interval. Results show that the average relative density of the parameters is 96.03%, 99.58%, and 99.15%, with the energy density less than 40 J/mm^3, 40 to 75 J/mm^3, and more than 75 J/mm^3, respectively. Results also show that at the energy density value of 55 J/mm^3, the relative density values are greater than 99.8% and exhibit the optimal stability; therefore, defined as the optimum energy density values. The optimum mechanical properties were measured with this energy density parameter (P = 360 W, t = 0.05 mm, s = 550 mm/s, h = 0.24 mm). Compared with the traditional casting method, SLM helps increase tensile strength by 68%, yield strength by 45%; elongation by 13%, and hardness by 62%. The result demonstrates that the rapid cooling factor under the SLM process produces fine grain refinement to achieve excellent mechanical properties.
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