- 期刊
超薄延性鑄鐵件成型條件及金相組織之研究
Study on Molding Conditions and Metallographic Microstructure of Super Thin Section Ductile Iron Casting
摘要
本研究在探討濕砂模之一般重力澆鑄及於澆杯處垂直施以氣壓(最大瞬間壓力約為 0.2kg/cm^2)時，對於具有不同厚度(1.0、1.2、1.4、1.6、1.8、2.0、2.5、2.8mm)之超薄延性鑄鐵件之成型條件(成型度、表面缺陷)以及金相顯微組織之影響。研究結果顯示，在加壓之條件下，對超薄延性鑄鐵件而言，其成型度與表面缺陷程度與一般重力鑄造相比，有明顯的改善；以厚度1.0mm薄件試片而言，其成型度由32.29%上升至84.09%，提升了51.80%；而厚度1.2mm試片之成型度則由65.09%上升至99.36%，提升 了34.27%。一般重力澆鑄及於澆杯處垂直施以氣壓時：(1)金相顯微組織之石墨、波來鐵、肥粒鐵及雪明碳鐵之含量皆無明顯差異。(2)鑄件厚度由1.0mm增加至2.8mm時，球化率先增後減，球墨數遞減，球墨粒徑遞增。(3)隨鑄件厚度增加，變態粒滴斑鐵及波來鐵(此兩種混合物即為俗稱之白鑄鐵)組織隨之減少，當鑄件厚度為2.5mm時則完全消失。(4)對本實驗之超薄鑄鐵試片(厚度1.0~2.8mm)而言，其質量效果不明顯。(5)鑄造狀態且無白鑄鐵組織條件下，延性鑄鐵能充填之最薄斷面厚度為2.5mm。
並列摘要
The purpose of this study is to investigate the effect of pressurized(the maximum instantaneous pressure is 0.2kg/cm^2) on the green sand mold when pouring for molding conditions(fillability degree, surface defects) and metallographic microstructure of the different thickness specimens(1.0mm、1.2mm、1.4mm、1.6mm、1.8mm、2.0mm、2.5mm、2.8mm). The result of experiment show that when in the condition of pressurized for super thin section ductile iron specimens have significantly improved in fillability. For example about the thin specimens 1.0mm, the degree of fillability improvement is from 32.29% to 84.09%, rised 51.80%. And the degree of improvement about 1.2mm specimens is from 65.09% to 99.36%, rised 34.27%. When in the conditions of pressurized and unpressurized system for super thin section ductile iron specimens. (1) Have no significant difference in metallographic microstructure for specimens thickness from 1.0mm to 2.8mm. (2) The distribution ratio for graphite、pearlite、 cementite and ferrite have no obviously difference. (3) When the casting specimens with increasing thickness, along with reducing about transformed ledeburite and pearlite (white cast iron). (4) The mass effects for the different thickness specimens are also not evident.(5) In as-cast condition with no white cast iron microstructure, the super thin section ductile iron specimens can completely filling thickness is in 2.5mm.