薄壁球狀石墨鑄鐵之研發

Research on the Production of Thin-Wall Ductile Iron Castings

盧彥富

指導教授 ： 邱弘興

國立臺灣師範大學/科技學院/工業教育學系/碩士(2002年)

摘要

本研究為設計一階級薄板(2mm、4mm及6mm)，來探討製程參數對薄壁球墨鑄鐵件之影響。首先在相同的碳當量(目標值4.8%)下，針對接種劑和球化劑的種類與添加量對不同厚度(2mm、4mm及6mm)的薄壁球墨鑄鐵件組織均勻性之探討。其次，在相同的碳含量(目標值3.9%)下，探討矽含量、接種劑與球化劑之種類及添加量與鑄模塗層等製程參數對於球墨數、球化率、肥粒鐵百分率及碳化物百分率等組織均勻性與抗拉機械性質之影響。
實驗結果顯示，在較高的碳當量(約4.6%~4.8%)下，以濕砂模可成功製造出2mm厚(70mm×60mm)的低碳化物(5%以下)薄壁球墨鑄鐵件。
欲獲得較佳組織均勻性及抗拉機械性質之薄壁球墨鑄鐵件，其製程條件為: C.E.值控制為4.66%(3.67%C，2.97%Si)、模穴有上塗層(石墨液)、添加1.0%的 S-70接種劑及1.0%的C.G.球化劑。2mm厚度之鑄件其球墨數可達2673/mm2以上，球化率可達90%。基地肥粒鐵百分率可達76%以上，碳化物百分率低於5%。平均抗拉強度可達
56 kg/mm2，伸長率為7%。

關鍵字

薄壁 ； 球墨鑄鐵 ； 碳化物

並列摘要

The primary purpose of this research was to nvestigated the effects of molten metal processing variables on the stepped thin-wall ( 2, 4 and 6 mm in thickness ) ductile iron castings. First, the carbon equivalent ( 4.8 % ) was controlled, the effects of homogeneous microstructure on the stepped thin-wall ductile iron castings with various inoculants, spheroidizer and their addition amount was investigated. Second, at the same carbon content ( 3.9 % ), to study the effects of processing variables, such as, addition amount of Si, type of inoculants and its addition amount, spheroidizing treatment, solidification cooling rate and mold coating on the microstructure and mechanical properties of the thin-wall ductile iron castings.

The experimental results show that production of the thin-wall ( 2 mm in thickness ) ductile iron castings with carbide fraction less than 5 % was successful by using green sand mold at higher ( 4.6 % ~ 4.8 % ) carbon equivalent.

To get thin-wall ductile iron castings with better homogeneous microstructure and mechanical properties, the processing variables are carbon equivalent under 4.66 % ( 3.67 % C, 2.97 % Si ), mold cavity with graphite coating, adding 1.0 % inoculant S-70 and 1.0 % spheroidizer C. G. The nodule count and nodularity of the castings with 2mm thickness can be up to 2673/mm2 and 90%. The ferrite fraction of matrix can be up to over 76 %, the carbide fraction under 5 %, the average ultimate tensile strength up to 56 kg/mm2, and 7 % elongation.

並列關鍵字

Thin-wall ； Ductile iron ； Carbide

參考文獻

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5. A. Javaid, J. Thomson, M. Sahoo and K.G. Davis, “Factor Affecting the Formation of Carbides in Thin-Wall DI Castings”, AFS Trans. Vol 107, 1999, pp.441-456.

9. G.van der Graaf, H.E.A. van den Akker and L. Katgerman, “Flow Phenomena of Mold Filling for Thin-Wall Iron Castings”, 60 th World Foundry Congress, Sep 26, 1996.