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標題: | 高錳合金鋼塑性變形誘發機械雙晶之研究 The study of deformation twins in high manganese steels |
作者: | Hui-Chin Wang 王惠琴 |
指導教授: | 楊哲人 |
關鍵字: | TWIP鋼,疊差能,退火雙晶,變形雙晶,穿透式電子顯微鏡, TWIP steel,stacking fault energy,annealing twin,deformation twin,TEM, |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本研究以Fe-24Mn-0.6C(wt.%)雙晶誘發塑變(Twinning-Induced Plasticity, TWIP)鋼之不同晶粒尺寸,探討晶粒尺寸對TWIP鋼之影響。實驗以平均晶粒大小約為10μm(小晶粒)和100μm(大晶粒)的板材,在室温下壓縮變形,其變形量分別為為0%、2%、10%和20%的厚度減薄量。並利用光學顯微鏡和穿透式電子顯微鏡來觀察材料之顯微組織,以硬度量測來分析材料之機械性質。退火後小晶粒鋼之硬度值大於大晶粒鋼,滿足Hall-Patch方程式,且大小晶粒鋼之硬度值皆隨著變形量之增加而大幅增加。退火後大晶粒鋼之退火雙晶密度高於小晶粒鋼。在2%變形量下,小晶粒鋼中僅觀察到一種變形雙晶系統和差排,而大晶粒鋼中除了差排,還觀察到多種變形雙晶系統及疊差。當變形量由2%增加至10%時,大小晶粒鋼中的變形雙晶及差排密度皆增加,而在大晶粒鋼中觀察到多個疊差互相交錯。當變形量增加至20%時,大晶粒鋼中已觀察不到疊差的存在。
研究之另一部分則是比較Fe-24Mn-0.6C(wt.%)和Fe-24Mn-4Al-0.6C(wt.%)合金鋼,在相同的熱處理及變形量下,利用光學顯微鏡和穿透式電子顯微鏡觀察材料之顯微組織,以測量硬度值來分析材料之機械性質,並探討鋁元素對TWIP鋼之影響。退火後含鋁鋼相較於不含鋁鋼之平均晶粒尺寸較大,硬度值則較弱。經由計算,含鋁鋼的疊差能為58.7(mJ/m^2),而不含鋁鋼的疊差能為29.2(mJ/m^2)。塑性變形後,兩種鋼材中都有觀察到差排及變形雙晶的存在,其中含鋁鋼的雙晶密度相較於不含鋁鋼低。 The influence of grain size in a Twinning-Induced Plasticity (TWIP) steel, with the composition of Fe-24Mn-0.6C (wt. %), are investigated by microscopy (OM), transmission electron microscopy (TEM), and Vickers hardness test. Samples with average grain size of 10μm (fine-grain) and 100μm (coarse-grain) were compressed with different deformation amounts at room temperature. After annealing, the annealing twin density in coarse-grained is higher than in the fine-grained, but the hardness in fine-grained is higher than the coarse-grained. With small deformation (2% thickness reduction,) the fine-grained steel produced a few of deformation twins and dislocations; moreover, only one twinning system are observed. Compared with the fine-grained steel, the similar microstructure also shown in the coarse-grained steel; however, there are more twinning systems can be found and some stacking faults exist in it. With the deformation amount up to 10%, the deformation twin density and the number of twinning systems increase in both of the fine-grained and coarse-grained steel. Besides, there are many stacking faults intersect in the coarse-grained steel. Up to 20% deformation amount, it is hard to find the stacking faults but deformation twins even in the coarse-grained steel. The effect of aluminum content in Fe-24Mn-0.6C (wt. %) alloy steel is also investigated, based on the same heat treatment and deformation amounts, with the utility of OM, and TEM, and the Vickers hardness test. After annealing, the average grain size in the Fe-24Mn-4Al-0.6C(wt.%) alloy steel is larger than the Fe-24Mn-0.6C (wt. %) alloy steel, but the hardness value in steel without aluminum is larger than the steel with aluminum. The stacking fault energy (SFE) is calculated for the steel with aluminum is 58.7 (mJ /m^2) and for the one without aluminum is 29.2 (mJ /m^2). After deformation, dislocation and twins are found in both of steels, but twin density in the steel without aluminum is higher than the other one. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64004 |
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顯示於系所單位: | 材料科學與工程學系 |
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