本論文研究經由盤捲模擬後的錳鋼，於725oC持溫30分鐘後空冷至室溫，接著在冷軋延後，以快速加熱方式得到雙相極細晶之顯微組織。試片中之極細晶沃斯田鐵相，由於晶粒細小且呈現長條狀，故在拉伸變形初期TRIP效應並不明顯，直到有相當變形量之後，應變誘發麻田散鐵方能大量啟動，致使加工硬化率提高，使其在具有高強度的同時，又能保有良好的延展性。本論文亦研究拉伸至特定延伸率之顯微組織，各相比例及分佈，藉此探討極細晶錳鋼的塑性變形行為。

In this study, a steel alloying with Mn was used to obtain ultrafine-grained two phase structure by rolling and heat treatment. By cold rolling and rapid thermal annealing, submicroned fine and thin lath austenite grains were obtained. During the early stage of tensile test, fine austenite grains were found quite stable, only after some deformation, these fine austenite grains started to transform into martensite, so that cause a high work hardening rate, therefore the tensile strength and elongation obtained are very high. Due to strain-induced martensitic transformation, deformation localization which normally occurred in ultrafine-grained metals can be avoided. The change of deformed microstructure was investigated in details.

一、前 言 1
二、文獻回顧 2
2-1 細晶發展 2
2-1-1 Hall-Petch關係 2
2-1-2 極細晶粒的變形行為 3
2-2 極細晶材料的生成 5
2-3 錳鋼的變形機制 9
2-4 晶粒形貌對於沃斯田鐵的穩定性 10
2-5 拉伸過程的相變化行為 12
三、研究目的 16
四、實驗方法 17
4-1 實驗材料 17
4-2 熱處理製程與冷軋延 17
4-3 金相製備 17
4-4 拉伸試驗 18
4-5 顯微組織觀察 18
4-6 背向散射電子繞射分析 18
4-7 X光繞射分析 19
五、實驗結果 20
5-1 退火後之顯微組織觀察 20
5-1-1 原始熱軋試片 20
5-1-2 熱軋試片經熱處理過後 20
5-1-3 冷軋後試片 21
5-1-4 冷軋試片經熱處理過後 22
5-2 拉伸變形之行為觀察 23
5-2-1 機械性質 23
5-2-2 拉伸後之破斷面 24
5-3 晶粒尺寸分析 25
5-4 特定延伸率下之變形行為觀察 26
5-4-1 變形之顯微組織 26
5-4-2拉伸變形行為 27
5-4-3 EBSD之相變化行為分析 27
5-4-4 EBSD之相比例分析結果 29
5-4-5 XRD之分析結果 30
六、討論 31
6-1 晶粒形貌對TRIP效應的影響 31
6-2 拉伸過程的變形行為 32
6-3拉伸變形時的相變化行為 33
七、結論 35
八、參考文獻 36

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