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題名 | 薄壁球墨鑄鐵表層異常組織對於熱疲勞性質之影響=Effect of the Abnormal Skin Structure on Thermal Fatigue Property of Thin-Wall Ductile Cast Iron |
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作者 | 盧祥安; 潘永寧; Lu, S. A.; Pan, Y. N.; |
期刊 | 鑄造工程學刊 |
出版日期 | 20130900 |
卷期 | 39:3=158 2013.09[民102.09] |
頁次 | 頁1-12 |
分類號 | 472.2 |
語文 | chi |
關鍵詞 | 薄壁球墨鑄件; 田口實驗; 表層異常組織; 塗模劑; Thin wall ductile iron; Taguchi’s experiment; Abnormal skin structure; Mold coating; |
中文摘要 | 本研究是針對薄壁球墨鑄件,探討一些關鍵冶金及製程參數對於鑄件表層所形成之異常組織(如:石墨退化、缺石墨區、全波來鐵層或全肥粒鐵層、碳化物等)的影響,並探討可以降低或消除該表層異常組織之方法。本研究所探討之冶金及製程參數包含:澆鑄溫度、殘留鎂量、接種方法、造模材料、塗模劑種類等。最後,本研究亦深入分析異常表層組織之形成機制。田口實驗分析結果顯示,針對高溫澆鑄之2mm、3mm及6mm試片而言,對於抑制表層異常組織之最佳參數為:球化劑1.2wt%+澆斗接種0.6wt%、石墨塗模劑及呋喃模硬化劑/呋喃樹脂比例為60-80wt%;針對低溫澆鑄而言,最佳參數為:球化劑1.2wt%+澆斗接種0.6wt%、SiO2塗模劑及呋喃模硬化劑/呋喃樹脂比例為80wt%。惟,MgO塗模劑、SiO2及石墨塗模劑三者之差異不大,但均較未使用塗模劑者有顯著抑制表層異常組織之效果。針對熱疲勞性質而言,耐熱疲勞性質隨表層石墨異常組織面積之增加而降低。此外,較厚之鑄件(如:6mm)及較高的澆鑄溫度(如:1723°K(1450°C))會增加熱疲勞壽命。最後,本研究亦探討合金在熱循環過程中,顯微組織之變化情形以及熱疲勞破壞機制。 |
英文摘要 | The primary purposes of this research are threefold: (1) to study the effects of metallurgical and processing parameters on the formation of the abnormal structure on the skin of the thin-wall ductile iron castings, (2) to explore the mechanisms for the formation of the abnormal skin structure, and (3) to correlate the skin abnormal structure in terms of degraded area with the thermal fatigue life of the thin-wall ductile iron castings.Taguchi's analysis results indicate that among the three types of coating (graphite, SiO2 and MgO) investigated, graphite coating exhibits the most effective when poured at a relatively high pouring temperature (1723°K(1450˚C)), while SiO2 is the most favorite coating for a relatively low pouring temperature (1673°K(1400˚C)). Nevertheless, no significant difference in effectiveness on the prevention of the abnormal skin structure was observed among these three coatings, but MgO coating shows the least variations in the degraded area of the abnormal skin structure. Furthermore, significant improvement was obtained when a coating was applied as compared to the case of without coating.Regarding the thermal fatigue property, the thermal fatigue life increases with decreasing the degraded area of the abnormal skin structure. In addition, increased thermal fatigue life was registered for castings poured at a relatively higher temperature, i.e., 1723°K(1450 ˚C), and with a thicker section, i.e., 6 mm. Finally, the phenomenon of microstructure transformation and the failure mechanism during the cyclic thermal process were analyzed in this study. |
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