雷射粉床熔融（LPBF）是金屬積層製造中常見的加工方法之一。由於加工參數之間複雜的相互作用，因此在加工過程中經常會產生如孔洞(pores)，變形 (distortions) 和微裂紋 (micro-cracking) 的缺陷。鎳基超合金 Inconel 713LC (IN713LC) 被視為是一種不可焊接的合金，其在金屬積層製造中有嚴重的微裂紋產生。本研究建立一系統化的最佳化方法以尋找鎳基超合金IN713LC的最佳加工參數區域。該最佳化方法結合了減少微裂紋和熔池缺陷的觀點。因此，在最佳加工參數區域中的參數可以產生高密度和低裂紋的工件。在找到最佳加工參數區域後，本研究設計一系列的實驗，以找尋最佳雷射間格距離 (hatching space) 及加工參數產生裂紋多寡的判斷標準。在各個參數製造的樣本中，其熔池尺寸、形狀和裂紋密度皆不相同。在觀察各參數對應的結果後，發現一趨勢為，糊狀區域 (mushy zone) 越大，裂紋發生的可能性越高，且最佳加工參數區域中樣本的裂紋密度最低為0.015％，工件密度最高可以達到99.96％，進而驗證了最佳加工參數區域有效性。最後，本研究設計一拉伸試驗棒實驗，並將印製出的試驗棒進行拉伸測試。其結果與鑄造工件的機械性質進行比較，發現藉由印製的拉伸棒具有比AMS 5377更好的降伏強度和極限抗拉強度，但有較低的伸長率。因此本研究認為，將雷射粉床熔融印製的IN713LC拉伸棒進一步熱處理後，能有效提高拉伸試驗棒的伸長率。本研究為首個研究不可焊接合金Inconel 713LC的團隊，並建立優化加工參數區域圖，其可有效地印製高密度和較少裂紋的工件。因此，該方法被證實可顯著地減少傳統試誤法所需進行的大量實驗時間和資源。

Laser powder bed fusion (LPBF) is one of common processing methods in additive manufacturing. Since the complex interactions of the processing parameters, the defects such as pores, distortion and micro-cracking are often produced during the process. Inconel 713LC, which was known as a non-weldable alloy, is subjected to severe solidification cracking during the LPBF process. In the present study, a systematic optimization method was con-structed to find the optimal parameter region of IN713LC in LPBF additive manufacturing. The optimization method combines the perspectives of reducing the micro-cracks and the pores in melt pool, therefore, the optimal region of the processing map can provide workpieces with less-crack and high-density. The specimens were fabricated with various fabrication parameters, leading to different melt pool sizes, shapes and different crack density. The corresponding results in a trend could be observed that the larger the mushy zone is, the higher the susceptibility of crack occurrence. As a result, the crack density of the specimens in the optimal parameter region has the lowest number down to 0.015%. The relative highest density of a 3D part in the optimal parameter region can reach up to 99.96%. Thus, the validation of the optimal processing map is successfully confirmed. At last, a tensile test for the as-printed tensile bars was applied for comparisons with the mechanical properties of the testing bars in the casting process. It is found that the result of the tensile test has the better strength, but the lower elongation than that in AMS 5377. The further heat treatment is suggested for effectively improving the elongation of testing bars in Inconel 713LC fabricated by LPBF. It is concluded that we are the first group to study a non-weldable alloy, Inconel 713LC, in establishing an optimal processing map to effectively fabricate less crack and high density of a 3D part. Thus, the proposed method has been proved to significantly reduce the time, resources, and effort to conduct a large amount of experiments based upon trial-and-error approach or design of experiment (DoE).

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