熱均壓(Hot Isostatic Pressing, HIP)技術已廣泛應用於鑄造工業以去除鑄造過程中所產生之內部孔隙，其結合了高溫及高壓方式以提供材料較佳的性質，並能改善鑄造材料的強度、延展性與疲勞壽命。Inconel 718是使用在航太工業上最多的超合金材料，同時具有高溫優越的抗腐蝕性、強度、潛變及疲勞等性質。
不同的熱處理形成不同的顯微結構，不當的熱處理處理將造成有害相的析出，降低Inconel 718的機械性質。本研究探討在經過熱均壓製程後，後續固溶熱處理溫度以及時效熱處理時間兩個參數，求得最佳參數。
在研究中發現，晶界上Laves相及δ相的析出，將造成機械性質的下降。固溶處理溫度1020 oC持溫1小時後完全固溶Laves相及δ相，其抗拉強度為1331.5 MPa；固溶處理溫度1060 oC持溫1小時將使NbC部份固溶，而於時效處理時以薄膜狀析出，強度降低為1298.8 MPa。因此最佳固溶處理參數為1020 oC持溫1小時。
經過不同時效時間處理，γ〞於720 oC持溫8小時降溫至620 oC持溫4小時尺寸為30.41 nm，為尖峰時效(peak aging)，具有最大強度1407.2 MPa。此外若以達到鑄造超合金最低標準，在商業上時效處理以720 oC持溫2小時降溫至620 oC持溫8小時為最佳參數，抗拉強度為1185.4 MPa。

Hot Isostatic Pressinng (HIP) is widely used in the casting industry to remove the internal porosity generated during the casting process. It combines higher pressure and temperature to produce materials and parts with substan- tially better properties than other methods. These results in the improved strength, ductility and fatigue life of castings. Inconel 718 is the most widely used superalloys for aerospace applications. The Inconel 718 niclkel-base superalloy has decent corrosion resistance high of temperature and ambient temperature, and excellent creep and fatigue strengths at high temperature.
However, the unsuitable heat treatments will give to the precipitation of detrimental phases.
The aim of this paper is to discuss the heat treatment, including solution temperature and aging heat treatment time paramters after HIP process, and ultimately to reach proper microstructural control and mechanical properties.
Experimental results show that the reduced mechanical strength of Inconel 718 is due to Laves and δ phases on the grain boundary. The Laves and δ phases dissolve completely in the 1020oC, 1hr solution treated condition, and show the ultimate tensile strength (UTS) of 1331.5 MPa. NbC carbides dissolve partly under 1060oC, 1hr solution treatment, will precipitate with thin film shapes after aging treatment, and the UTS reduces to 1298.8 MPa.The optimized solution treatment condition is 1020oC, 1hr.
γ〞has the diameter of 30.41 nm under the double aging at 720oC, 8hrs and furnace cooling to 620oC followed by 620oC, 4hrs and air cooling. It shows the largest UTS of 1407.2 MPa, will be a peakaging theatment. Besides if the purpose of the UTS is to reach the casting superalloy basic standards, the commercial treatment of aging treatment is 720oC, 2hrs and furnace cooling to 620oC followed by 620oC, 8hrs and air cooling, show the UTS of 1185.4 MPa.

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