本研究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)單道次、多道次、單層面及雙層面列印試件為基礎，分析各加工參數之列印試件於熔融區域凝固後之表面形貌。為了探討熔池行為對表面形貌的影響，將藉由商用數值模擬軟體FLOW-3D建立三維選擇性雷射燒熔之理論模型。
本研究使用材料為工業上常用的AA6061作為實驗及模擬對象，在三維空間下建立仿真粉末分布粉床、多道次及多層面熱流耦合模擬。為了驗證模型分析準確度，將與實驗結果進行比較，得到熔池尺寸之理論值與實驗值之誤差百分比小於10%之內；且表面粗糙度理論值與實驗值之絕對誤差大都小於1 μm，說明此三維熱流耦合模型具一定精確度及可靠性。並藉由此分析模型及實驗結果的配合，進行熔池形貌、雷射間距及多層堆疊形貌間的關係研究，結果顯示粉末粒徑分布會影響最終熔池形貌；越小的雷射間距，因為重複燒熔次數較多，使得最終熔池形貌更加平整；且後續堆疊形貌會受前一層表面形貌影響。此外，也針對試件表面進行缺陷及機械性質檢測，結果顯示較高雷射功率出現裂紋缺陷；而量測之簡化楊氏模數與微硬度均隨著雷射掃描速率增加而上升。由此可說明試件之表面形貌與機械性質均隨加工參數變化，因此在最佳化參數預測上，需同時考量此兩種影響因子，以建立工藝參數圖，供未來製程上加工參數的選擇。

This research aimed to analyze the appearances of the selective laser melting (SLM) printing results, provided by Industrial Technology Research Institute (ITRI), with various processing parameters settings. To explore the physic phenomenon of the metal powder being heated through laser, an SLM theory model was built through a commercial numerical simulation software FLOW-3D.
We established a powder bed with a real particle size distribution, multi-pass, and multi-layer in three-dimensional simulation. To validate the accuracy and reliability of the theoretical model, AA6061, a commonly used material in the industry, was used in the simulation and experiment. The percentage errors of dimension of the molten pool between theoretical and experimental value was within 10% and the absolute errors of surface roughness between theoretical and experimental value was within 1 μm, indicating the theoretical model has decent accuracy. Finally, we discussed how different laser processing parameters affected the melting results based on the simulated model and experimental results. The results showed that surface morphology was affected by particle-size distribution. Smaller hatch distance had more remelting times, which could make the molten pool smoother. And the following stack morphology was affected by previous layer surface morphology. Furthermore, we did defects and mechanical properties inspections on the surface of the samples. The results showed that microcrack defects appeared at higher laser power and reduced Young’s modulus and microhardness both increased as the laser scanning speed increased. It can be explained that the surface morphology and mechanical properties of the samples changed with the processing parameters. Therefore, in the optimization of parameter prediction, these two influencing factors need to be considered at the same time to establish a process parameter diagram for the selection of processing parameters in the future process.

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