稀土應用於鋼中還在起步階段，本研究利用稀土鈰做為熱力學計算與實驗主要探討對象，目的建構一可預測介在物種類於不同鋼材成分與熱處理溫度之計算模組，為使計算方法盡可能地貼近實際煉鋼情況，由Wagner’s交互作用模型為基礎，考慮各種鋼水中雜質元素之相互影響，衍伸出兩步驟之計算，並將各步驟整理為一連續計算模組。模組之可靠性藉由實驗添加鈰於鋼中，並進行不同溫度之熱處理，後於SEM及EPMA下觀察及統計不同介在物種類出現之比例，進而與計算結果相互比較。
將不同實驗條件之鋼材進行介在物種類統計與分析，結果顯示與計算模組相符合，可確定其可靠性，其中可發現鈰添加進行深度脫氧後，試片硫氧含量分別於: [O]=5-11 ppm、[S]=8-30 ppm時，介在物種類常為Ce2O2S、Ce2O3、CeAlO3此三種介在物較穩定存在材料中，針對此三種較常出現之種類進行形貌、尺寸與型態深入分析，發現Ce2O2S尺寸常為2 μm左右，且形貌常為扁平正圓形，為一軟質介在物；Ce2O3則分布較為大型為3-4 μm且形貌較為凸出，偏向硬質介在物；CeAlO3尺寸與Ce2O2S接近，表面形貌常出現雙色分布，由EPMA分析可知其為Al分布不均所造成。

Oxide Metallurgy is a method that could be used to effectively utilize the formation of inclusions to improve the steel quality by pinning grain boundary or forming IAF. Previous studies shows that the deoxidization and desulphurization ability of Ce is higher than Al and Ti, the commercialized deoxidizer,. Therefore, Ce was chosen as the main deoxidizing agent in present research to form the inclusions that could be used to improve the steel quality and to reach the higher cleanliness of steel. In present study, we focus on predicting the inclusion types which could be applied to oxide metallurgy. Wagner’s interaction model (ai = fi * [% i ] ; log fi = ∑_i^j▒〖e_i^j*[ %i ]〗) was applied to build a calculation model to predict the formation of inclusions after the deoxidization and desulphurization process. A thermodynamic prediction module of Ce inclusions was constructed and shows a promising results which is proved by the experiment using Ce as the main deoxidizing agent. The sample was investigated after it was quenched from high temperature. There are three types of inclusion usually formed such as Ce2O2S, Ce2O3, CeAlO3. Furthermore, the size, shape morphology and profound characteristic of each type of inclusion were also studied.

摘要 I
SUMMARY II
致謝 X
總目錄 XII
表目錄 XIV
圖目錄 XV
第一章 前言 - 1 -
1-1 研究背景 - 1 -
1-2 研究目的 - 3 -
第二章 文獻回顧 - 5 -
2-1 非金屬介在物 - 5 -
2-1-1 非金屬介在物簡介 - 5 -
2-1-2 非金屬介在物改質方式 - 6 -
2-2 氧化物冶金 - 7 -
2-2-1 氧化物冶金背景 - 7 -
2-2-2 氧化物冶金原理 - 8 -
2-2-3 氧化物冶金應用 - 10 -
2-3 稀土與非金屬介在物 - 11 -
2-3-1 稀土介紹 - 11 -
2-3-2 稀土在鋼中作用 - 13 -
第三章 實驗方法及步驟 - 20 -
3-1 介在物預測計算方法 - 20 -
3-1-1 第一階段交互作用-元素交互作用 - 21 -
3-1-2 第二階段交互作用-介在物交互作用 - 28 -
3-1-3 模組建立 - 33 -
3-2 實驗流程及步驟 - 40 -
3-2-1 鈰添加方法 - 40 -
3-2-2 二次熱處理 - 41 -
3-2-3 試片後處理 - 42 -
3-3 分析方法 - 48 -
3-3-1 化學組成分析 - 48 -
3-3-2 SEM/EDS介在物統計 - 48 -
3-3-3 EPMA介在物分析 - 49 -
3-3-4 TEM介在物分析 - 49 -
第四章 結果與討論 - 51 -
4-1 介在物種類模組計算結果 - 51 -
4-2 介在物種類預測計算與實驗結果對照 - 56 -
4-3 常見介在物特性分析 - 63 -
4-4 介在物形貌分布統計 - 74 -
4-5 介在物尺寸分布統計 - 82 -
第五章 結論 - 87 -
第六章 參考文獻 - 89 -

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