臺灣博碩士論文加值系統

本研究的主旨是探討球墨鑄鐵在使用水冷式冷激塊做單向熱傳控制的凝固過程中，凝固特性與冷卻速率的關係。澆鑄模是由呋喃砂模與水冷式冷激底座組合而成，經由水流量及水溫的設定來控制冷激鋼模的冷激效果。為了比較，有一組實驗的鑄模全部採用呋喃模。利用安插在鑄模中的熱電偶，量測鑄塊在澆鑄凝固過程的溫度變化。並將鑄塊切割取出試片做金相微觀組織的分析。
實驗結果顯示，接近冷激模位置的之片狀石墨及球狀石墨皆比無冷激之鑄件組織細小。在不同的冷卻速率，觀察到石墨的形態分別有：片狀、球狀、蠕蟲狀石墨以及牛眼組織結構。由熱電偶組記錄到的溫度冷卻曲線，可以估算出凝固過程中之溫度梯度，G，液相線移動速度，RL，及固相線移動速率，RS，以及固-液共存區的範圍。

Abstract
This paper is aimed to study the relationship between the solidification behaviors and cooling rate of ductile iron when solidified under the unidirectionally controlled heat transfer with a water cooled chilling block. The casting mold was a compound mold with a wall of Furan sand mold set on top of a chilled block, the chilling effect was achieved by setting water flow rate and water temperature. For comparison, a set of experimental was conducted by just using furan mold and without chilling block. The thermocouples were mounted into the mold cavity to measure the temperature curve during casting solidification . The microstructure of casting were also examined.
The results show that the size of flack graphite and nodular graphite are smaller in the vicinity of chilled surface. With different cooling rate, the morphology of graphite show out as flake, nodular, vermicular and bull-eye structure. From the recorded cooling curve , it is able to calculate out the temperature gradient, G, and growth rate, RL and RS, during solidification.

目錄
中文摘要......................................................Ⅰ
英文摘要......................................................Ⅱ
誌謝..........................................................Ⅲ
目錄..........................................................Ⅳ
圖表索引......................................................Ⅵ
符號索引......................................................Ⅸ
第一章前言.................................................1
第二章原理及文獻探討.......................................3
2.1 鑄鐵之簡介............................................3
2.2 鑄鐵之凝固、元素之影響................................3
2.2.1 碳當量............................................4
2.2.2 球墨鑄鐵中合金元素的影響..........................5
2.3 球墨的成長與退化......................................7
2.4 石墨的形態與冷卻曲線的關係............................9
2.5 單向凝固(unidirectional solidification)..............10
第三章 實驗方法.............................................20
3.1 冷激鋼模及冷卻系統製作...............................20
3.2 呋喃砂模製作.........................................21
3.3 配料、熔煉及澆鑄.....................................22
3.4 冷卻溫度曲線的量測...................................23
3.5 試片製作.............................................24
第四章 實驗結果與討論.......................................33
4.1 鑄件之溫度變化曲線...................................33
4.2 冷卻水溫及冷卻曲線的關係.............................37
4.3 固-液相線之分佈情形..................................38
4.4 金相顯微結構與冷卻速率的關係.........................40
4.5 冷卻速率與溫度梯度的關係.............................42
第五章結論與建議..........................................68
參考文獻.....................................................70
附錄.........................................................73
作者簡介.....................................................78

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