本研究首先以工業技術研究院雷射與積層製造科技中心提供之選擇性雷射燒熔(Selective laser melting, SLM)單、多道次列印試件為基礎，分析各加工參數的熔融區域與單、多道次列印凝固後之表面形貌。隨後以COMSOL Multiphysics多重物理量耦合模擬軟體建立選擇性雷射燒熔的理論分析模型。我們試圖透過模擬的方式尋找出最佳化參數，節省實驗大量的成本及時間花費。
在本研究中，使用工業上常用的Ti6Al4V做為實驗以及模擬的對象，
建立多道次熱流耦合模型，藉由相場法模擬雷射燒熔時熔池的聚合現象(Fusion)，並進行熔池形貌與加工參數間關係的研究，結果顯示越小的雷射間距會使得重複燒熔區間越大，同時重複燒熔次數也會增加。而重複燒熔將會導致原有的熔池與新熔池進行重新聚合，使得最終熔池形貌更加平滑。同時，我們透過仿真粉末分布模型分析金屬粉末粒徑對於熔池形貌的影響，並且與實驗及等粒徑模型進行結果比較。在熔池寬度的驗證比對中，誤差有明顯的下降。對於熔池尺寸的理論值與實驗值的誤差百分比皆落在20%以內。因此說明了真實粉末粒徑以及孔隙率設定的重要性。
　　我們藉由奈米壓痕機針對熔池剖面進行微硬度及楊氏模數的量測。結果顯示，微硬度會隨雷射能量密度增加而上升；楊氏模數則會隨著雷射能量密度增加而下降。這與Ti6Al4V金相變態過程有密切關聯，並藉由X光繞射儀實驗量測結果驗證我們的說法。
　　最後，我們以模擬結果中熔池的燒熔及聚合情況區分成四種型態，並將其繪製成工藝參數圖，提供未來在製程上的最佳化參數選擇。

In this research, we first did the analysis of melting region and surface profile on single track and multi-track experiment samples by selective laser melting (SLM) from ITRI for Ti6Al4V. After the analysis of experimental sample, we built the numerical model for SLM with COMSOL Multiphysics to simplify the analysis process in selective laser melting. And we tried to find the optimal parameters to save time and reduce cost through the simulation way. In this study, we used Ti6Al4V, which is commonly used in industry, as the object of experiment and simulation material. We built up a multi-track and heat-fluid coupling model. We simulated the fusion of the melting pool for laser melting with Phase field method, and we study on the relationship between the melting pool morphology and processing parameters. The results show that the smaller the hatch distance, the larger remelting area. And the remelting times also increase. The remelting pool will rebuild the geometry with new melting pool and make it smoother. Simultaneously, the effect of the particle size of the metal powder on the morphology was analyzed by the random particle deposition model and compared with the experimental results. The results show that the error of melting pool width had apparently decline. Also, the other error persentage for melting pool sizes between theoretic and experimental values were under 20%. Therefore, it’s explained that the importance of random particles setting and powder porosity. We used nanoindenter to measure the microhardness and Young’s modulus of the melting pool profile. The results show that the microhardness will increase with the increase of laser energy density and the Young’s modulus will decrease with the increase of laser energy density, which were closely related to Ti6Al4V metallurgical transformation process. Conseqently, we verified our statement with the experiment by X-ray diffractometer. Finally, we categorized the parameters into four types based on the simulation results. And we plotted a process parameter diagram to provide the optimization parameters for the process.

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