摘 要
Inconel 738LC作為燃氣渦輪發動機關鍵零件材料，以其優異的高溫強度與抗潛變性廣泛應用。然而，其高鋁鈦含量使其在同材質銲補時極易產生熱裂紋和液化裂紋，被歸類為難以銲接材料。為改善其修補性，本研究選用具備良好高溫強度且銲接性更佳的Inconel 625合金作為銲補材料，並以雷射金屬沉積(Laser Metal Deposition, LMD)技術沉積於Inconel 738LC鑄造母材上，系統性研究並比較多種熱處理條件對微結構及機械性質之影響，包括Inconel 738LC的傳統熱處理(1120°C/2h固溶+850°C/24h時效)、738LC優化熱處理(1175°C/2h固溶+850°C/24h時效)、Inconel 625對應之固溶+時效處理(1150°C/2h+700°C/24h)，以及700°C/24h的直接時效處理。結果顯示，不同熱處理皆對銲補區與母材機械性質有明顯影響。其中，直接時效試片展現出最優異的常溫拉伸性能，抗拉強度達934.8MPa，延伸率提升至15.7%，其斷裂位置發生於Inconel 738LC母材而非銲補區，顯示銲補品質優異且銲補區強度已超越母材。綜合而言，直接時效處理兼具製程簡單、能耗低與優異機械性質等優點，是本研究中最具應用潛力的熱處理條件。關鍵詞：雷射金屬沉積、Inconel 625、Inconel 738LC、熱處理
ABSTRACT
Inconel 738LC, as a critical material for gas turbine engine components, is widely applied due to its excellent high-temperature strength and creep resistance. However, its high Al and Ti content makes it highly susceptible to hot cracking and liquation cracking during repair welding with the same alloy, classifying it as a difficult-to-weld material. To improve its repairability, this study employed Inconel 625 alloy, which possesses good high-temperature strength and superior weldability, as the filler material. Laser Metal Deposition (LMD) was applied to deposit Inconel 625 onto theInconel 738LC casting, and a systematic investigation was carried out to compare the effects of various heat treatment conditions on the microstructure and mechanical properties. The treatments included the conventional heat treatment of Inconel 738LC(1120 °C/2 h solution + 850 °C/24 h aging), the optimized heat treatment of Inconel 738LC(1175 °C/2 h solution + 850 °C/24 h aging), the corresponding solution + aging treatment for Inconel 625 (1150 °C/2 h + 700 °C/24 h), and a direct aging treatment at 700 °C/24 h. Among them, the directly aged specimen exhibited the best room-temperature tensile properties, achieving an ultimate tensile strength of 934.8 MPa and an elongation of 15.7%. Moreover, the fracture occurred in theInconel 738LC substrate rather than in the deposited region, suggesting superior repair quality and that the strength of the deposited zone had surpassed that of the substrate. Overall, the direct aging treatment demonstrated advantages of simplicity, lower energy consumption, and excellent mechanical performance, making it the most promising heat treatment condition identified in this study.Keywords: Laser Metal Deposition, Inconel 625, Inconel 738LC, Heat treatment