本論文研究經過不同退火溫度之極細晶中錳鋼冷軋板，其拉伸行為有很大差異的原因。中錳鋼熱軋板經過冷軋延後在三個不同的退火溫度進行臨界退火(intercritical annealing)。對不同退火溫度的試片進行特定伸長量的拉伸試驗，並研究其變形組織。部分的試片在拉伸過程中即在γ相中產生細長條狀之應變誘發麻田散鐵相而得到TRIP效應。本研究比較不同退火溫度的試片在拉伸試驗前的微結構與相分佈，以及在相同的應變量下，不同條件試片所發生的變化。實驗發現不同的臨界退火溫度對於試片中的組織有顯著的影響，700℃持溫30分鐘後空冷的熱處理條件所得到的機械性質表現最為優秀，兼具高強度與高伸長量，其組織為接近等量的γ相與α相晶粒所組成，其中γ相的相分率稍高於α相。而在675℃進行退火的試片其組織為肥粒鐵及雪明碳鐵相，因此TRIP效應無法出現，變形是由肥粒鐵相的變形負責。在750℃退火的試片，其組織由高比例的的γ相與較少的α相所組成，此時的沃斯田鐵相在室溫下穩定性較低，故在受應力後立即產生大量應力誘發麻田散鐵而有較高的加工硬化率與較低的延伸率。

Abstract
　　The aim of this thesis is to understand the reason for the significant different of the tensile behavior of a cold-rolled medium Mn steel after different annealing temperatures. Hot-rolled medium Mn steel is heated at 725oC, then furnace cooled to room temperature. After cold rolling, the medium Mn steel is intercritically annealed at three different temperatures then air cooled to room temperature. Tensile tests were carried out on the specimens with different annealing temperatures, and it was found that annealing temperature strongly affects the tensile behavior and microstructures of theses specimens. Tensile deformation of the specimens annealed at 675℃ was found caused by the deformation of ferrite grains, while strain-induced martensitic transformation was found occurred in the specimens annealed at 700℃, showing TRIP-aided effect. Due to the low stability of austenite, stress-induced martensite was formed in the early stage of tensile test in the specimens annealed at 750℃, which resulted in a very high work hardening rate and poor elongation.

目錄
一、前言 1
二、文獻回顧 2
2-1錳鋼的發展 2
2-2沃斯田鐵相的穩定性 7
2-2-1 合金元素的影響 7
2-2-2 退火溫度的影響與晶粒尺寸效應 14
三、研究目的 32
四、實驗方法 33
4-1 實驗材料 33
4-2 試片準備 33
4-3 拉伸實驗 33
4-4 X光繞射分析 33
4-5 顯微組織觀察 34
4-6 EDS與EBSD分析 34
五、實驗結果 35
5-1 拉伸試驗結果 35
5-2 試片初始顯微組織之觀察 36
5-3 不同應變量之顯微組織觀察 37
5-4 X光繞射分析結果 38
5-5 EBSD成分分析結果 39
5-6 EDS化學成分分析 40
六、討論 41
6-1 熱處理溫度對微觀組織的影響 41
6-2 熱處理溫度對合金相組成成分的影響 41
6-3 熱處理溫度對拉伸性質的影響 42
七、結論 45
八、參考文獻 46

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