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題 名 | 7075鋁合金壓鑄件縮孔指標之研究=Study of Shrinkage Porosity Criterion for Die Casting of 7075 Aluminum Alloy |
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作 者 | 張峰旗; 郭哲豪; 黃文星; 楊俊彬; 吳春甫; | 書刊名 | 鑄工 |
卷 期 | 27:4=111 2001.12[民90.12] |
頁 次 | 頁31-37 |
分類號 | 472.2 |
關鍵詞 | 鑄鍛合一; 7075鋁合金; 縮孔指標; Hybrid casting and forging process; 7075 aluminum alloy; Shrinkage criterion; |
語 文 | 中文(Chinese) |
中文摘要 | 7075鋁合金是鍛造用鋁合金,本研究從鑄鍛合一製程開發的觀點,針對7075鋁合金的壓鑄件,來探討其縮孔的模擬預測指標。 本研究是採用Niyama指標(G/R),來預測縮孔,即G/R值小於等於某一預定值ε時,即可能在那位置會有某一型態的縮孔出現。ε的值會隨著不同的鑄造合金及縮孔的大小型態而不同。本研究以7075鋁合金先壓鑄成圓盤型鑄件,圓盤設計成有三個不同的厚度,其厚度分別是15mm、10mm及5mm,因其不同的縮孔型態來探討7075鋁合金形成不同型態的縮孔其所對應的G/R的指標值。 由實驗的結果5mm厚度的試片其縮孔率為0.1%,平均縮孔大小為0.398mm,縮孔相當小而且量也不多,對應的ε值在1∼0.9之間。而10mm厚度的試片其縮孔率為0.4%,平均縮孔大小為0.73mm,可以發現縮孔較大、量也較多,對應的ε值在0.645∼0.54之間。 而15mm 厚度的試片其縮孔率為0.9%,平均縮孔大小為1.262mm,可以發現有大型縮孔、總量也增加,其所對應的ε的值則在0.455∼0.43之間。 |
英文摘要 | 7075 aluminum alloy is a forging alloy. However, from the perspective of hybrid casting and forging process, it is desirable to cast 7075 aluminum alloy as pre-form for subsequent forging. This study is to investigate the criterion for shrinkage porosity prediction in die casting of 7075 aluminum alloy. With the criterion, it is then possible to assess the feasibility of using hybrid casting and forging process for 7075 aluminum alloy. In this study, Niyama criterion is employed to predict the formation of shrinkage porosity in casting. With the criterion, a certain degree of shrinkage porosity is expected to form when G/R value at the concerned location is smaller than a specific value, ε. G is the thermal gradient and R is the cooling rate. The value of ε changes when the extent/size of the shrinkage porosity is examined. Then, solidification simulations are conducted for that casting and Niyama criterion is employed to predict the occurrence of the shrinkage porosity whit a prescribed value for ε. The procedure is iterated with various ε values until the predicted porosity is consistent with the observed one. Then the particular ε value is then designated as the criterion value for that particular extent/size of porosity. In his study, castings of circular disk shape with sted cross section are die cast with 7075 aluminum alloy. The step cross section has three different thicknesses, which are 15mm, 10mm and 5mm. The results show that the casting section of 5mm thickness has rather small amount of porosity of 0.1 percent. Through cross examination with the simulated results, the ε value is found to lie between 1 and 0.9. For the casting section of 10mm thickness, it has medium size porosity of 0.4 percent and the ε value is between 0.645 and 0.54. For the casting section of 15mm thickness, it has rather large porosity of 0.9 percent and its ε value is between 0.455 and 0.43. |
本系統中英文摘要資訊取自各篇刊載內容。