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題 名 | 微量元素(Pb、Bi、Sb)以及Ce對於厚件球墨鑄鐵顯微組織和機械性質之影響=Effects of Minor Elements Pb,Bi,Sb and Ce on the Microstructures and Mechanical Properties of Heavy Section Dutile Cast Irons |
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作 者 | 駱新田; 潘永寧; | 書刊名 | 鑄工 |
卷 期 | 24:1=96 1998.03[民87.03] |
頁 次 | 頁23-45 |
分類號 | 472.2 |
關鍵詞 | 球墨鑄鐵; 微量元素; 機械性質; Ductile iron; Minor elements; Pb,Bi,Sb & Ce; Mechanical properties; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究主要係探討微量元素Pb、Bi和Sb以及Ce之中和作用對於厚件球墨鑄鐵顯 微組織及機械性質之影響。研究結果顯示,厚鑄件在較長的凝固時間情況下,球墨組織會發 生劣化而析出各種不規則或惡化型(如塊狀)石墨。當分別添加微量Pb(0.005%)、Bi(0.003%) 或Sb(0.008%)時,球墨組織可獲得改善,並增加球墨數目。但當上述微量元素之含量過多時, 球墨組織又再度發生劣化現象。惟,Pb、Bi和Sb之有害影響可藉由添加適當比例的稀土元 素(Ce)給予中和,研究結果指出Ce/Pb=0.9-1.4,Ce/Bi=0.8-1.1以及Ce/Sb=0.4-0.9均可獲 致理想的球墨組織。 另一方面,本研究亦探討厚件球墨鑄件其顯微組織與機械性質之關係。對於Pb系列實驗 而言,因Pb或Pb+Ce之添加而造成顯微組織之變化對於抗拉、降伏強度和硬度之影響極微, 其主要原因是當球墨組織發生劣化時,基地肥粒鐵量亦伴隨降低(或波來鐵量增加),此二因 素對於強度和硬度之影響會互相抵消。但對於伸長率和衝擊值而言,添加0.005%Pb或以Ce 完全中和Pb後,均有明顯的提升,此係上述二因素(即球墨組織獲得改善及肥粒鐵量增加) 均有利於韌性之提升。Bi系列之結果與Pb系列相似。 由於Sb是一波來鐵促進元素,故當添加微量Sb時(0.008%),可改善球墨組織,但波來 鐵量亦增加,因此鑄件之強度和硬度增高,但延性和衝擊值則降低。當添加過量之Sb時(e.g. 0.016%),伸長率和衝擊值大幅下降,而強度和硬度則稍微上升。當過量Sb之有害影響被Ce 完全中和後,球化率和球墨數目均大幅提高,且肥粒量亦增加,此使得延伸率和衝擊值明顯 提升,但強度和硬度則稍稍下降。 本研究亦以SEM觀察試片之破斷面,以分析厚件球墨鑄鐵之顯微組織與破壞特性之關 係。 |
英文摘要 | The effects of minor elements, i.e. Pb, Bi, and Sb. and Ce on the microstructures and mechanical properties of heavy section ductile cast irons were investigated in this study. The experimental results indicate that degenerate forms of graphite tend to precipitate in ductile iron castings that solidify over an extended period of time. Additions of small amounts of minor elements, such as 0.005%Pb or 0.003%Bi or 0.008 %Sb, result in increased nodule count and improved nodularity. However, substantial graphite deterioration occurs as the addition amounts of those minor elements become excessive, for instance 0.015%Pb. or 0.006%Bi. or 0.016%Sb. The subversive effects of Pb, Bi and Sb can be neutralized by rare earths (Ce) addition in appropriate ratios, i.e., Ce /Pb =0.9, Ce /Bi = 1.1 and Ce / Sb =0.9. Changes in the microstructures of heavy section ductile irons brought about by Pb additions and / or Ce neutralization exert no significant influence on both tensile and yield strengths. The is due to the fact that an improvement in both nodularity and nodule count (in the case of a small Pb addition or Ce neutralization) also promotes ferrite formation, These two factors counteract each other in terms of strength. However, the tensile ductility and impact values are substantially increased as the graphite nodularity and nodule count are increased. Similar results were obtained for Bi. With respect to Sb, due to its being a strong pearlite promoter. the tensile strengths tend to increase but the elongation and impact values are greatly reduced as the Sb addition amount is increased. When the harmful effect of Sb was completely neutralized by Ce, the ductility and toughness are increased significantly, but the strength and hardness are slightly decreased. |
本系統中英文摘要資訊取自各篇刊載內容。