- 學位論文
矽固溶強化肥粒鐵基球墨鑄鐵之研究
Study on the Silicon Solution Strengthened Ferritic Ductile Cast Iron
摘要
本研究評估分析固溶強化肥粒鐵基球墨鑄鐵(Solution Strengthened Ferritic Ductile Cast Iron, SSF)，所謂之第二代球墨鑄鐵，在不同Si含量(4.0wt%、4.3wt%、4.5wt%)之機械性質特性。並在相同的強度等級下，比較SSF球墨鑄鐵、傳統肥粒鐵-波來鐵基球墨鑄鐵以及沃斯回火球墨鑄鐵等三種球墨鑄鐵之機械性質及厚度敏感性(section size sensitivity)。 研究結果顯示，SSF球墨鑄鐵之抗拉強度與降伏強度皆隨Si含量的增加而增加，但伸長率則隨之減少。此係由於Si會固溶於肥粒鐵相內，而具有硬化及強化肥粒鐵相內之作用。另一方面，SSF球墨鑄鐵之衝擊值會隨Si含量之增加而降低，此與Si之脆化作用有關。此外，SSF規格之球墨鑄鐵之硬度變化(或厚度敏感性)均較傳統肥粒鐵-波來鐵基球墨鑄鐵及沃斯回火球墨鑄鐵稍低。 在相同的抗拉強度等級下，SSF球墨鑄鐵之降伏強度優於傳統之肥粒鐵-波來鐵基球墨鑄鐵，而伸長率則可達傳統球墨鑄鐵之2~3倍，但衝擊值則較傳統球墨鑄鐵為低。ADI之基地組織為沃斯肥粒鐵與殘留沃斯田鐵之組合，故其整體之強度等級顯著優於SSF球墨鑄鐵，但SSF球墨鑄鐵之伸長率則明顯優於ADI。此外，與傳統球墨鑄鐵及SSF球墨鑄鐵比較，ADI具有極佳的衝擊韌性。
並列摘要
The objective of this research is to evaluate the property characteristics of solution strengthened ferritic ductile iron (SSF), the so-call second generation of ductile irons, with different Si contents, ranging from 4.0 to 4.5 wt%. In addition, the properties of SSF ductile irons (grade EN-GJS-600-10) were compared with the conventional ductile iron grade of EN-GJS-600-3 and the Austempered Ductile Iron (ADI) grade of . The tensile test results of SSF ductile irons show that both the tensile and yield strengths increases, while the elongation decreases, as the Si content increases. This is due to the solution strengthening effect of Si on the ferrite phase in the matrix. However, the impact property of SSF ductile irons decreases with increasing Si content due to its embrittling effect. Furthermore, the variation in hardness or the section size sensitivity is the least for SSF, which is followed by ADI, and then the conventional ductile irons. At an approximately same level of tensile strength, SSF ductile irons exhibit higher yield strength and much better elongation (some 2 to 3 times higher) than the conventional ductile irons. On the other hand, both the tensile and yield strengths and impact property of ADI are substantially higher than those of SSF ductile irons, however, the elongation values of ADI are much lower than those of SSF ductile irons.