積層製造相較傳統製造，不僅能減少耗材的損失，且能賦予產品更複雜的幾何結構，是製造業相當重大的技術，本文以SLM製造IN-718鎳基合金，分別探討SLM製程參數、熱處理及高溫氧化行為，最後與傳統製造之商用IN-718做比較。
　　設定SLM製程參數為製造的第一步，本研究針對製程參數中的雷射功率及掃描速度進行探討，且能將此兩項參數透過計算轉換成線性能量密度，根據本研究結果，雷射功率、掃描速度及能量密度對材料的機械性質有所變化，且在顯微組織中有更明顯的缺陷差異，因此對於產品的製造，優化製程參數能在不影響製造成本下，提高材料的性質。
　　IN-718是一種可進行析出硬化的鎳基合金，根據文獻指出典型的結晶相有γ相、γ′相、γ′′相、δ相、MC碳化物相及Laves相，透過熱處理能有效改變材料的結晶相，進而讓材料的機械性質更好。經過初步的SLM製程參數比較，本研究將最佳的SLM製程參數樣品進行熱處理，分別探討機械性質、顯微組織以及高溫氧化行為。當IN-718碰上高溫時，合金表面會生成一層氧化層，保護內部防止腐蝕，因此常被應用於高溫環境，如渦輪零件、發動機等。本研究為了更深入分析高溫氧化行為，將SLM樣品、熱處理過後的SLM樣品與商用Comm樣品放置於650℃環境中，滿足渦輪運作的工作溫度及規範，模擬實際應用的高溫環境，進而探討與比較，透過維氏硬度、SEM、EDS、XRD及Raman等儀器，分析各樣品在650℃的溫度下，呈現之機械性質、顯微組織、氧化層結構與氧化層厚度，根據實驗結果，經過熱處理的SLM樣品不僅在機械性質上表現最佳，且高溫氧化行為也呈現最好的狀態，其次則為SLM樣品，因此也表示SLM積層製造技術相對於傳統製造，能使產品擁有更好的性質。

Compared with traditional manufacturing, Selective Laser Melting (SLM) cannot only reduce the loss of consumables, but also provide products with more complex geometric structures. In this thesis, three experimental steps are designed: first, investigation of SLM manufacturing parameters on microstructure of this alloy; second, study of heat treatment influence on microstructure and properties of Inconel 718 manufactured by SLM; third, investigation of high-temperature oxidation behavior of SLM manufactured sample in as-printed and with heat treatment conditions and a commercially available Inconel 718. According to the microstructure investigations by Scanning Electron Microscopy (SEM) and Optical Microscopy (OM), high scanning speed can lead to defects such as pores, cracks, and un-melted particles. High energy density might cause spatter, resulting in spheroidization at the bottom of the molten pool. The sample with (200W, 700mm/s) showed the best microstructure with least defects and was chosen for further experiments in next steps. In the second step, heat treatment was applied to the chosen sample from the first step. It was found that heat treatment can effectively change the crystalline phase of Inconel 718 manufactured by SLM and γ, γ′, γ′′, δ phases were detected in heat treated SLM sample. In addition, the microstructure of SLM-Inconel 718 changed dramatically as a result of heat treatment; a grainy microstructure structure was obviously formed after heat treatment. The heat treated SLM sample showed higher Vickers hardness values than the as-printed SLM sample. For the third step, in order to analyze the high-temperature oxidation behavior, this study exposed as-printed and heat-treated SLM samples and commercial samples to 650°C for different times of 1, 24, 48 and 72h to simulate the high-temperature environment of practical applications. According to microstructure investigations heat treated samples had more homogenous oxidation than as-printed SLM and commercial samples. Moreover, heat-treated SLM alloy showed the highest value for Vickers harness in all oxidation times.

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