- 學位論文
不同單方向凝固速率對PWA1422鎳基超合金之高溫潛變性質之影響
Effect of Different solidification rate on the high-temperature behavior of PWA1422 Nibased superalloy
摘要
本實驗採用MAR-M200+Hf 鎳基超合金以原材及進行DS 下抽速率60mm/hr、120mm/hr 和180mm/hr 之單方向凝固製程。再進行熱處理固溶溫度為1200℃/4hr/ArC，搭配第一次時效1100℃/4hr/ArC 和二次時效900℃/32hr/ArC，並探討其高溫潛變(982C/207MPa)，觀察微觀組織對機械性質的影響。利用掃描式電子顯微鏡(Scanning Electron Microscopy, SEM) 對微觀組織做觀察。實驗結果顯示，相同的熱處理條件下，DS 下拉速率60mm/hr 其高溫潛變(982C/207MPa)性質為最好，從SEM 圖分析因為下拉速率60mm/hr 試棒冷卻速度慢，γ´形狀慢慢成長為dendrite形狀，γ´相呈現非均質情況，MC 型碳化物與γ/γ´共晶相數量多且分布廣泛，造就最潛變機械性質有較好的現象，另外從SEM 拍攝樹枝狀晶可以發現主要枝晶間距和二次枝臂間距都會隨著下抽速度之增加而減小。
並列摘要
In this study, MAR-M200 + Hf nickel-based superalloy was used Polycrystalline and superalloy with withdraw rate of DS 60mm/hr、120mm/hr、180mm/hr.Standard heat treatment procedures are solution treatment at 1200 ℃ for 4hr / ArC, the first aging at 1100 ℃ for 4hr /ArC and followed by second aging at 900 ℃ for 32hr /ArC，Mechanical behavior experiments were high temperature creep test at 982℃/207MPa. The microstructure was observed by Hardness Test and Scanning Electron Microscopy (SEM). The experimental results show that the same heat treatment conditions, the withdraw rate of DS 60mm/hr the high temperature mutation (982 ° C / 207MPa) is the best, from the SEM analysis because the pull-down rate of 60mm / hr bar cooling speed is slow The shape grows slowly into the shape of dendrite, and the γ'phase exhibits heterogeneity. The number of MC type carbides and γ / γ'eutectic phase is large and widely distributed, which makes the most sublimable mechanical properties better.