鎳基超合金Inconel 738由於具有良好的高溫機械性質及抗腐蝕能力，經常使用於氣渦輪機高溫段動葉片材料。葉片在長時間運轉下，易因高溫疲勞、腐蝕、潛變及異物撞擊(FOD)等因素造成葉面或頂部氣封環傷損。為降低運轉維護成本，輕微受損之葉片通常可使用強度稍低的Inconel 625粉末搭配同軸雷射來披覆銲補，但若欲銲修頂部氣封環等需要高強度材料的部位，則須使用與母材相同強度之Inconel 738粉末。
Inconel 738因銲接性差，母材在無高溫預熱的情況下實施雷射披覆銲補易發生凝固熱裂及HAZ液態龜裂。本研究旨在探討高溫預熱雷射披覆銲補製程之參數，過程中並輔以X-ray殘留應力量測，觀察披覆銲補與銲後固溶時效處理對於殘留應力的影響，最後再進行高溫拉伸及潛變破斷試驗以比較銲補試片與母材試片之高溫機械性質。
研究結果顯示Inconel 738葉片試片於預熱溫度780~900℃，雷射功率1800W與走速900 mm/min之參數下，施以Inconel 738雷射粉末披覆銲補可得到無凝固熱裂及接近母材強度之銲道，未來可將成果實際應用於Inconel 738氣渦輪機葉片之雷射披覆銲補。

Nickel-based superalloy Inconel 738 has been applied as a material for gas turbine blade due to its excellent mechanical strength and anti-corrosion ability in high temperature operation environment. After long time service, blade surface or top of seal ring area could be damaged cause of high temperature fatigue, corrosion, creep and foreign object damage (FOD). In order to reduce operation and maintenance costs, typically use lower strength powder such as Inconel 625 with coaxial laser to repair the slight damage blade. However, it shall use Inconel 738 powder to repair the top of seal ring which needs strength as high as base metal .
Due to poor weldability, it could occur solidification crack and HAZ liquation crack when Inconel 738 powder clad on the Inconel 738 BM without high pre-heat temperature. This study is to find out parameter of laser cladding with high pre-heat temperature, and use X-ray residual stress analyzer to watch for changes in residual stress of weldment after cladding and heat treatment, and finally verify the strength of cladding layer with high temperature tension test and creep rupture test.
The results reveal that the specimen of Inconel 738 blade cladded with pre-heat temperature of 780~900℃, laser power 1800W and travel speed 900 mm/min, will get approximate strength to base metal without solidification crack, so that high temperature laser cladding can be applied in practical repair of Inconel 738 gas turbine blades.

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