本論文研究中錳鋼之熱軋鋼板經兩階段熱處理及冷軋後，熱處理溫度及持溫時間對其顯微組織及拉伸性質。第一階段熱處理產生組織為肥粒鐵相加上大量細小且均勻分佈的碳化物，其所富含之碳和錳合金，在第二階段熱處理時，隨著碳化物的回溶會提供周圍組織豐富的碳和錳，使碳化物周遭形成次微米細晶粒的沃斯田鐵。次微米晶粒能夠幫助提高沃斯田鐵穩定性，以利於變形時發生TRIP效應。改變冷軋量對試片的相分率、化學成份、晶粒尺寸和長寬比沒有明顯的影響，因此對拉伸性質的影響不大。但冷軋25%和50%並於750℃熱處理1小時之試片具有不同的拉伸性質。熱處理溫度和時間會影響組織的相分率、成份重新分佈和晶粒尺寸等，進而影響其拉伸性質。熱處理溫度提高或是持溫時間增加都能幫助碳化物溶解，若要使碳化物大量溶解則熱處理的溫度至少需高於700℃，持溫時間則至少需超過5分鐘。

This study explores the effect of annealing temperature, time and amount of cold rolling on the microstructure and tensile properties of a medium manganese steel after two-stage annealing and cold rolling procedures. After the first stage annealing, the microstructure consists of ferrite and tiny carbides. During the second stage annealing, the carbides are dissolved and provide abundant manganese and carbon to the surrounding ferrite matrix, which then transforms into submicron austenite grains. The small grain size of the austenite increases the austenite stability, and let TRIP effect occurs during deformation.Diffirent cold roll reduction gave similar phase fraction, composition, grain size and aspect ratio, but 25% and 50% cold rolling followed by 750℃ annealing 1 hour gave diffirent tensile properties. Annealing temperature and time affect austenite fraction, alloy partition and grain size, which in turn affect the tensile properties of the steel. To make enough carbides to be dissolved, the annealing temperature should be higher than 700℃, and the annealing time should exceed 5 minutes.

論文審定書 i
中文摘要 ii
英文摘要 iii
圖目錄 viii
表目錄 xvii
一、前言 1
二、文獻回顧 2
2-1 麻田散鐵 2
2-1-1 條狀麻田散鐵 2
2-1-2 盤狀麻田散鐵 3
2-1-3 由條狀至盤狀麻田散鐵之變化 3
2-1-4 應變誘發麻田散鐵之成核 4
2-2 TRIP鋼 5
2-2-1 應力和應變誘發麻田散鐵 5
2-2-2 不連續TRIP效應 6
2-3 室溫下沃斯田鐵穩定性 7
2-4 合金成份對TRIP鋼的影響 8
2-5 晶粒尺寸的影響 9
2-6 雙相區退火處理 9
2-6-1退火溫度對材料的影響 10
2-6-1-1 最佳之退火溫度 10
2-6-1-2 退火溫度對晶粒尺寸的影響 11
2-6-1-3 退火溫度對Ms溫度的影響 11
2-6-1-4 退火溫度對機械性質的影響 12
2-6-2 退火時間對材料的影響 12
2-6-2-1退火時間對機械性質的影響 13
2-6-2-2退火時間對穩定性和晶粒尺寸的影響 13
2-7 冷加工 13
2-7-1 冷加工的效果 13
2-7-2 不同冷軋量以及單次或多重冷軋對材料顯微組織和拉伸性質的影響 14
2-8 中錳鋼 14
2-9 碳化物的溶解 16
三、研究目的 19
四、實驗方法 20
4-1 實驗材料 20
4-2 試片準備 20
4-3 金相製備 20
4-4 拉伸實驗 20
4-5 掃描式電子顯微鏡 21
4-6背向散射電子繞射分析 21
4-7 成份分析 21
4-8 X-ray繞射分析 21
五、實驗結果 23
5-1 實驗參數 23
5-2 熱軋後經第一階段熱處理之微觀組織與硬度 23
5-3 經冷軋及雙相熱處理後之實驗結果 24
5-3-1 試片經冷軋25%後在熱處理溫度750℃下分別持溫1分鐘至10小時 24
拉伸性質 24
微觀組織 25
相分率 26
晶粒尺寸和長寬比 27
EDS化學成份分析 27
5-3-2 試片經冷軋50%後在熱處理溫度750℃下分別持溫1分鐘至10小時 28
拉伸性質 28
微觀組織 28
相分率 29
晶粒尺寸與長寬比 30
EDS化學成份分析 30
5-3-3 試片經冷軋25%後在熱處理溫度700、725和750℃下持溫10分鐘 31
拉伸性質 31
微觀組織 31
相分率 32
晶粒尺寸與長寬比 32
EDS化學成份分析 33
5-3-4 試片經冷軋25%，在熱處理溫度750℃下持溫5分鐘後拉伸至特定應變量 33
拉伸性質 33
微觀組織 34
相分率 34
晶粒尺寸與長寬比 35
EDS化學成份分析 35
六、討論 36
6-1 第一階段熱處理 36
6-2 熱處理時間對材料拉伸性質和組織的影響 36
6-3 冷軋量對材料拉伸性質和組織的影響 40
6-4 熱處理溫度對材料拉伸性質與組織的影響 41
6-5 特定應變量下微觀組織與相分率的變化 43
七、結論 45
八、參考文獻 46

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