臺灣博碩士論文加值系統

本研究針對9Cr-1Mo鋼裸材、9Cr-1Mo鋼熱浸鍍鋁材及經750 ℃ 熱處理後之9Cr-1Mo鋼熱浸鍍鋁材，進行750 ℃ 高溫拉伸及熱腐蝕潛變試驗，探討不同條件之9Cr-1Mo鋼高溫機械性質及熱腐蝕環境之潛變行為。
實驗結果顯示，9Cr-1Mo鋼於750 ℃ 高溫潛變下，析出物明顯成長粗化，促使板狀麻田散體邊界遷移，使材料硬度降低。於熱腐蝕環境，鋼料受腐蝕鹽攻擊產生之內侵蝕孔洞不會影響材料潛變壽命，但在最後發生頸縮時會加速潛變孔洞連結，使材料伸長率下降。試片經熱浸鍍鋁後，鋁層有效提升材料抗腐蝕能力，使試片伸長率維持。但由於鋁化層之高溫強度低於9Cr-1Mo鋼，且鋁化層形成的過程造成9Cr-1Mo鋼截面積減薄，使試片熱腐蝕潛變壽命減少6小時。試片熱浸鍍鋁後經熱處理，因Fe / Al交互擴散形成微孔洞，於後續潛變過程容易產生裂口，降低鋁化層與底材之附著性，因此熱腐蝕潛變壽命較熱浸鍍鋁材減少1小時。

The aim of this study was to investigate high temperature mechanical property and hot corrosion creep resistance of 9Cr-1Mo steel, hot-dip aluminized 9Cr-1Mo steel, and heat-treated after hot-dip aluminized. The experiment was conducted in 750 °C high temperature tensile and hot corrosion creep test.
The experimental results show that under high temperature creep test of 750 °C, precipitation of 9Cr-1Mo steel obviously grows and coarsens, which promotes the migration of lath martensite grain boundary. Thus the hardness of the material was reduced. In a hot corrosive environment, the internal erosion of the steel caused by the corrosion does not affect the creep life. But in the final necking it will accelerate the connection of the pore, so that cause the decreased of the elongation. After the hot-dip aluminizing of the 9Cr-1Mo steel, the aluminide coating highly improved the corrosion resistance, therefore maintaining elongation. However, since the high-temperature strength of the aluminized coating is lower than the 9Cr-1Mo steel, the process of forming the aluminized layer in the hot-dip aluminum causes the cross-sectional area of the 9Cr-1Mo steel to be thinned, so the hot corrosion creep life was reduced by 6 hours. After hot-dip aluminizing and heat-threated, micropores are formed by Fe/Al interdiffusion. It is easy to produce cracks in the subsequent creep process and reduce the adhesion between the aluminized layer and the substrate. Therefore, the hot corrosion creep life is reduced by one hour compare to hot-dip aluminizing specimen.

第一章 前言 1
第二章　文獻回顧 3
2.1　9Cr-1Mo合金鋼 3
2.1.1　合金元素之作用 4
2.1.2　微觀結構 6
2.1.2　析出物型態 7
2.2　潛變 9
2.2.1　潛變曲線 9
2.1.2　潛變機制 11
2.2.3　9Cr-1Mo鋼潛變性質 13
2.2.4　Larson-Miller 壽命評估 14
2.3　熱腐蝕 15
2.3.1　熔鹽熱腐蝕 15
2.3.2　NaCl / Na2SO4混合鹽之熱腐蝕 17
2.4　熱浸鍍鋁 20
2.4.1　熱浸鍍鋁技術 20
2.4.2　熱浸鍍鋁之鋁化層 21
2.4.3　熱浸鍍鋁後高溫擴散與孔洞之生成 23
第三章　實驗方法 25
3.1　實驗流程 25
3.2　實驗材料製備及前置處理 26
3.2.1　試片製備 26
3.2.2　熱浸鍍鋁製程 27
3.2.3　熱浸鍍鋁後熱處理 27
3.3　高溫回火試驗 29
3.4　高溫拉伸試驗 30
3.5　潛變試驗 31
3.5.1　高溫潛變試驗 31
3.5.2　熱腐蝕潛變試驗 31
3.6　分析設備與方法 33
3.6.1　分析設備 33
3.6.2　分析方法 34
第四章　實驗結果 35
4.1　9Cr-1Mo鋼熱浸鍍鋁 35
4.1.1　熱浸鍍鋁塗層之截面金相 35
4.1.2　熱浸鍍鋁塗層經熱處理後之截面金相 36
4.2　9Cr-1Mo鋼高溫熱處理後相變及微硬度 39
4.3　9Cr-1Mo鋼高溫機械性質 43
4.4　9Cr-1Mo鋼高溫潛變試驗 49
4.4.1　9Cr-1Mo鋼高溫氧化潛變試驗 49
4.4.2　9Cr-1Mo鋼熱腐蝕潛變試驗 53
4.5　9Cr-1Mo鋼熱浸鍍鋁後熱腐蝕潛變試驗 58
第五章　討論 63
5.1　高溫潛變過程中底材之弱化 65
5.2　裸材熱腐蝕環境之潛變 66
5.3　熱浸鍍鋁於熱腐蝕環境潛變之作用 67
5.3.1　9Cr-1Mo鋼熱浸鍍鋁材 67
5.3.2　熱浸鍍鋁後經熱處理之作用 68
第六章　結論 69
參考文獻 70

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