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題 名 | 消失模A356鋁合金鑄件之顯微組織分析=Microstructural Analysis of the A356 Al Alloy Produced by the Evaporative Pattern Casting Process |
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作 者 | 謝志浩; 潘永寧; | 書刊名 | 鑄工 |
卷 期 | 25:3=102 1999.09[民88.09] |
頁 次 | 頁51-68 |
分類號 | 472.5 |
關鍵詞 | 消失模型鑄造法; A356鋁合金; 顯微組織; Evaporative pattern casting process; A356 Al alloy; Mirostructure; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究探討消失模型鑄造法之製程參數對於A356鋁合金鑄件顯微組織的影響,實 驗參數包括:流路系統、塗層厚度、抽氣及澆鑄溫度。對於EPC製程而言,由於金屬熔液 是直接澆鑄於模型上,模型熱分解所產生的液態及氣態產物必須由模穴逸出,熔液才能繼續 前進,又,保力龍模型之熱分解屬吸熱反應,此將致使熔液產生一冷激作用,再加上保力龍 模型的緩衝作用,使得EPC製程之熔液充填模式及鑄件顯微組織與空模穴CO 模有些許 差異。在EPC鑄件中,共晶含量往流動前緣呈微量增加的趨勢,且於部份鑄件之流動前緣 有明顯的共晶組織堆積現象。然而,在CO 模鑄件中,共晶含量並無明顯增加的趨勢,且 於流動前緣亦無共晶組織堆積的現象。 由於EPC鑄件之凝固冷卻速率較傳統空模穴者快,因此其顯微組織(如:初晶α-Al之 第二樹枝間距)較細密。此外,在EPC製程中,增加塗層厚度、提高澆鑄溫度、實施抽氣 等均會降低鑄件之凝固冷卻速率,而增大初晶第二樹枝間距。 此外,本研究亦探討製程參數對於鑄件孔洞率的影響。實驗結果顯示,鑄件孔洞率沿流 動前緣方向呈降低的趨勢。流路系統和塗層厚度對於鑄件孔洞率的影響不大,但提高澆鑄溫 度和實施抽氣則會大幅增加鑄件的孔洞率。 綜合本研究之結果,欲製造EPCA356合金鑄件之建議製程條件為:採用0.2mm之塗層 厚度、不實施抽氣、在可完全充模之情況下使用較低之澆鑄溫度(如720℃)。 |
英文摘要 | This study investigated the influence of several processing parameters, including the gating system design, the coating thickness, the application of a vacuum and the pouring temperature, on the microstructures of the EPC A356 Al alloy. Due to the endothermic nature of the degradation reactions of the EPS patterns and the sequential flow characteristic in the Al EPC molds, the melt front experinces a constant chilling effect during the pattern╱cavity filling process. As a result, the microstructures of the EPC Al castings differ slightly from those produced in the conventional empty cavity molds. It has been found that, in the EPC process, the Al-Si eutectic content increases slightly toward the downstream of the castings, and that an accumulated eutectic zone in the tip of the castings(melt front)can be observed as well. Nevertheless, in the CO process, the eutectic content remains more or less constant along the flow direction of the castings, and also no accumulation of eutectic phase has been detected at the melt front. The present results indicate that the SDAS is reduced by changing the gating system from S-T-V to T-S-H, but is increased with increasing the coating thickness and the pouring temperature, and also by the application of a vacuum. Regarding the casting porosity, the results show that he porosity content decreases progressively from the age entrance toward the melt front. In addition, the porosity content is only slightly affected by different gating systems employed and by varying the coating thickness, but is significantly increased by raising the pouring temperature and by the application of vacuum. |
本系統中英文摘要資訊取自各篇刊載內容。