臺灣博碩士論文加值系統

本研究主要是將數值模擬技術應用於17- 4PH不銹鋼的精密鑄造方案改良，並進行實驗比對。本研究使用套裝軟體模擬17-4 PH不銹鋼精密鑄件的模流凝固過程並預測其缺陷，進而對組樹的澆流道系統做改良，再與實際鑄件作驗證。本研究中亦針對17- 4PH不銹鋼鑄件進行微組織成核成長型態的模擬並做實驗驗證。

本研究首先利用DTA熱差分析與CA-CCA電腦輔助冷卻曲線分析方法，針對17- 4PH不銹鋼進行熱物參數的量測，求得17- 4PH之固液相線、固相率對溫度的曲線以及合金潛熱值，之後將所得數據代入模擬系統做計算。

本研究中選用的方案載具為一新式高爾夫球推桿，根據鑄造經驗存在一組初始組樹方案設計，該方案包含水平流道與垂直入水口的澆流道系統，以此方案進行實際鑄造發現鑄件有多處缺陷。利用商用鑄造軟體ProCASTTM模擬充填及凝固過程，並以熱點原理做缺陷預測比對，根據模擬結果推測缺陷發生原因為入水口位置設計不當導致補縮路徑被截斷，補縮不完全。因此針對澆流道系統進行改良，改變鑄件位置使入水口轉為水平方向，另外設計豎流道以增強模流，最後獲得一改良組樹方案，經實際澆鑄後鑄件品質良好，達到表面光滑的要求。

本研究亦使用3D-CAFÉTM模擬17- 4PH鑄件的成核成長型態，首先設計一對照組方案進行實驗，利用實驗與模擬結果找出合適參數，並應用於另一實驗組方案的微組織預測，比對模擬與實驗結果發現晶粒型態相當穩合，顯示此環境下該參數對於17- 4PH鑄件微組織模擬有足夠的可信度。

The research is aimed at applying the numerical modeling on the gating and riser designs for investment castings of 17- 4PH stainless steel, and experiments were conducted to verify the results. The commercial available computer-aided engineering software was employed to simulate the mold filling and solidification process in different runner systems, and predict shrinkages. Verification of numerical results was done by actual castings, and shrinkages were analyzed to modify the gating and runner system. Moreover, the simulation of microstructure for 17- 4PH stainless steel was carried out in this study; the results were also testified by the observations of the real castings.

Differential Thermal analyzer, DTA, and Computer-Aided Cooling Curve Analysis, CA-CCA, were adopted to measure the thermal property of 17- 4PH stainless steel, e.g. solidus temp., liquidus temp., the curve of solid fraction versus temp., and latent heat. The experiment data were applied for numerical modeling calculation.

The study case chose a new-style golf putter as a subject. An existed preliminary design of the runner and gating system was obtained by empirical, which composes of a horizontal runner and vertical gates. The experiment results showed inappropriate porosity distribution in the actual casting. The commercial software ProCASTTM was adopted to simulate mold filing and solidification process in the preliminary designed runner system, and predict the defects distribution with hot spot idea. Based on the results of simulation, the reason of defects occurrence was conjectured that the poor gating locations results in cut-off of feeding path; therefore molten liquid cannot feed into the entrapped area during solidification process. Thus, the runner system was improved to get a modified design of runner and gating system, including changing the orientation of castings, making the gates to the horizontal direction, and adding vertical runners to enhance melt flow. The practical production reveals defects were eliminated; the quality of the casting was satisfactory.

In this research, 3D-CAFETM was also used to simulate the nucleation and grain growth of 17- 4PH stainless steel castings. First, a control group was design to conduct experiments, and then a set of suitable parameters for numerical calculating were found out by comparison between the results of experiment and simulation. Applying this set of parameter to the simulation of experimental group, it shows a good correlation between the microstructure of actual 17- 4PH casting and the modeling result. The reliability of these microstructure parameters of 17- 4PH casting under this circumstance was proved.

目錄

中文摘要 I
Abstract III
致謝 V
目錄 VI
圖目錄 IX
表目錄 XII
符號表 XIII
第一章 序論 1
1.1 研究背景 1
1.2 文獻回顧 3
1.2.1 鑄造模擬解析回顧 4
1.2.2 微組織模擬回顧 6
1.2.3 縮孔形成理論回顧 7
1.3 研究目的 8
第二章 理論基礎 12
2.1 材料熱物性質量測 12
2.1.1 DTA (Differential Thermal Analyzer)熱差分析原理 12
2.1.2 CA-CCA (Computer-Aided Differential Thermal
Analysis)電腦輔助冷卻分析原理 12
2.2 電腦模擬鑄造系統之數學模式 16
2.3 缺陷預測理論 19
2.4 微組織模擬之數學模式 19
第三章 實驗方法 22
3.1 17- 4PH不銹鋼熱物性質量測 22
3.1.1 DTA熱差分析量測 22
3.1.2 CA-CCA電腦輔助冷卻曲線分析量測 22
3.2 實際鑄件澆注 27
3.2.1 高爾夫球推桿鑄件方案 27
3.2.2 微組織觀察實驗 28
3.3 數值模擬 36
3.3.1 模流凝固模擬解析 36
3.3.2 微組織模擬解析 36
第四章 結果與討論 40
4.1 17-4PH不銹鋼材料熱物性質量測結果 40
4.1.1 DTA熱差分析量測結果 40
4.1.2 CA-CCA電腦輔助冷卻曲線分析量測結果 40
4.2 高爾夫球推桿數值模擬之分析與預測 45
4.2.1 初始組樹方案實際鑄件之缺陷分佈 45
4.2.2 初始方案之模流凝固模擬結果與分析 45
4.2.3 改良方案之模流凝固模擬分析與預測 47
4.2.4 改良方案之實際鑄件比對 49
4.3 微組織型態模擬 60
4.3.1 對照組之微組織型態觀察 60
4.3.2 對照組之微組織模擬 61
4.3.3 實驗組之微組織模擬 63
4.3.4 實驗組之微組織型態驗證 65
第五章 結論 80
第六章 未來工作 82
文獻回顧 83

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