本實驗主要研究拉伸溫度及應變率對於中錳鋼之變形機制的影響。以10-5 s-1及10-3 s-1兩種應變率，在200 oC至400 oC間進行拉伸試驗，並藉由掃描式電子顯微鏡(SEM)、背向散射電子繞射(EBSD)以及穿透式電子顯微鏡(TEM)的分析，探討溫度與應變率對拉伸性質與顯微組織的影響，期望了解溫度與應變率對Fe-5.3Mn-2.3Al-0.35C-1.1Si中錳鋼變形行為的影響。
實驗結果顯示，在10-5 s-1應變率下，當變形溫度由200 oC上升至225 oC時，主要變形機構會由變形誘發變韌鐵相變化(Deformation-Induced Bainite, DIB)轉變為變形雙晶，在200 oC時最接近鋼材DIB之上限溫度，225 oC以後則由變形雙晶主導。然而變形雙晶於拉伸溫度提升到300 oC至350 oC時，隨著溫度上升而逐漸受到抑制。最後，在350 oC時，變形機構由變形雙晶逐漸轉變為以差排滑移(dislocation glide)為主的變形機構。
而當應變率提高至10-3 s-1時，由於應變率升高會增加材料之沃斯田鐵穩定性，變形誘發變韌鐵相變化會在較低變形溫度下受到抑制，變形雙晶機構於較低溫度出現。因此10-3 s-1應變率時，變形雙晶在200 oC左右逐漸轉變為主導的變形機構，在約300 oC時，變形機構再逐漸由變形雙晶轉變為差排滑移主導。

This study is aimed at understanding the effect of deformation temperature and strain rate on the deformation mechanism of a medium manganese steel, Fe-5.3Mn-2.3Al-0.35C-1.1Si. Under 10-5 s-1 and 10-3 s-1 strain rates, the tensile tests were carried out from 200 oC to 400 oC. The effects of deformation temperature and strain rate on tensile properties and microstructure behavior have been studied by scanning electron microscope (SEM), backscattered electron diffraction (EBSD), and transmission electron microscopy (TEM).
Experimental results showed that at a strain rate of 10-5 s-1, when the deformation temperature increased from 200 °C to 225 °C, the dominant deformation mechanism transforms from deformation-induced bainitic transformation (DIB) to twinning. 200 oC was the closest deformation temperature to the upper limit temperature of DIB, when the deformation temperature increased to 225 oC, the deformation mechanism was dominated by twinning. However, twinning was gradually suppressed as the deformation temperature increased from 300 oC to 350 oC. When the deformation temperature reached up to above 350 oC, the dominant deformation mechanism gradually changed from twinning to dislocation slip.
As the strain rate was increased to 10-3 s-1, the austenite stability of the steel was increased, hence, deformation-induced bainitic transformation (DIB) was suppressed at a lower deformation temperature and promoted twinning occurred. Therefore, at a strain rate of 10-3 s-1, twinning became the dominant deformation mechanism at about 200 oC, and near 300 oC, the dominant deformation mechanism was changed to dislocation slip.

論文審定書 i
中文摘要 ii
Abstract iii
目錄 v
圖目錄 viii
表目錄 xxi
一、前言 1
二、文獻回顧 2
2-1 第三代先進高強度鋼 2
2-2 變形誘發麻田散鐵與變韌鐵 2
2-3 沃斯田鐵穩定性 4
2-4 TWIP效應 6
2-4-1 變形雙晶與加工硬化的關係 6
2-4-2 疊差能對TWIP效應的影響 9
2-4-3 溫度對變形雙晶生成速率的影響 12
2-4-4 溫度對變形雙晶形貌的影響 13
2-5 變形溫度對變形機制的影響 14
2-6 應變率對變形機制的影響 18
三、研究目的 20
四、實驗方法 21
4-1 實驗材料 21
4-2 實驗步驟 21
4-3 拉伸試驗 21
4-4 顯微組織分析 22
4-4-1掃描式電子顯微鏡(Scanning Electron Microscopy, SEM) 22
4-4-2背向散射電子繞射儀(Electron Backscattered Scattered Diffraction, EBSD) 23
4-4-3穿透式電子顯微鏡(Transmission Electron Microscope, TEM)分析 23
4-4-4 X光能量散佈光譜儀(Energy Dispersive Spectrometers, EDS)分析 23
五、實驗結果 24
5-1 拉伸性質分析 24
5-1-1 10-5 s-1與10-3 s-1應變率下，工程應變為0.3時不同溫度之拉伸試驗 25
A、10-5 s-1應變率 25
B、10-3 s-1應變率 25
5-1-2 10-5 s-1與10-3 s-1應變率下，高溫區間拉伸試驗 26
A、10-5 s-1應變率 26
B、10-3 s-1應變率 27
5-2 Stereographic分析 28
5-3 顯微組織分析 29
5-3-1 10-5 s-1應變率拉伸試片 29
A、拉伸至工程應變為0.3時 (ε=0.3) 29
B、拉伸至試片破斷 (fracture) 33
5-3-2 10-3 s-1應變率拉伸試片 35
A、拉伸至工程應變為0.3時 (ε=0.3) 35
B、拉伸至試片破斷 (fracture) 36
5-4 變形雙晶之比例估算 38
六、討論 40
6-1 變形溫度與應變率對變形機制之影響 40
6-1-1 不同應變率下，200 oC和225 oC間的變形機制轉換 40
6-1-2 更高變形溫度下的變形機制轉換 41
6-2 顯微組織對拉伸性質的影響 43
6-2-1 200 oC和225 oC間，溫度與應變率對拉伸性質的影響 43
6-2-2 10-5 s-1應變率下，變形溫度對拉伸性質的影響 44
6-2-3 10-3 s-1應變率下，變形溫度對拉伸性質的影響 46
七、結論 47
八、參考資料 49

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